Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: SILVERGUN on October 29, 2012, 10:47:11 am
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OK, so I built an amp...after weeks of gathering parts, preparing a layout, drilling and cutting aluminum, and investing somewhere in the area of 182 hours,,, I am the proud father of a bouncing baby Trainwreck Express type (I didn't use the EXACT schematic or layout)......I really had no idea that there was a community dedicated to these things,,,,I saw the video with Glen and the interview with Ken, and I was moved to make THIS amp.
So I pluged it in, had a few minor problems, solved them (I'll discuss more later)....and now I have an amp that works great as-is but isn't really what "I" was looking for........here's pre-build info:http://www.el34world.com/Forum/index.php?topic=14476.
So let's do something about it...I'm going to be trying a few modifications in the coming weeks and I'll try to document them here...my goal would be to share EVERYTHING I have done, and will do, and get some sound clips up so you guys can get the feel for whats happening here.
The amp sounds great, especially cranked, but is very stiff and not very forgiving...
***DISCLAIMER***- I am not trying to build a Trainwreck Express "CLONE"...I'm trying to tweak the circuit to my tastes, and don't really have time to worry about NOS tubes, specific OT's, pre-rola Celestion's, specific capacitor/resistor types, exact layout, blah, blah, blah, blah, blah....thank you in advance for your concern, but I'm just not "that guy"
I built a nice clean circuit and it should and will sound like I want it to.....in fact I'm not going to call it a TW Express......I'l call it SG#001 or just 001
I'm trying to build an overdrive machine, with no external boost/OD/dist. pedal needed to get max OD....cleans are secondary, and the ones I'm am getting are totally acceptable....very nice actually.....the version of the schematic I used, was described as being a very mean, so I thought OK, I'll do this one....got it all wired up, and plugged in and thought "is that it?",,,, so I guess I'm spoiled, but that's the cool part of this, we can change it.
The first issue I had was a high pitch squeal which was easy to find, and the result of an obvious rookie mistake:
SOLUTION: I took the 820M "grid stopper" off the board and used a shielded wire right from the vol. pot to the resistor that I mounted on the tube socket pin....DUH!.....quite as can be now
Then I had another high pitched squeal coming from the NFB circuit if the Presence control was set to 2 or below only.
SOLUTION: I inserted a 250K pot in place of the NFB resistor and dialed in a sweetspot at 68K......replaced the stock 100K with a 68K resistor and not only did it respond better, but the Presence control squeal was gone.......the only problem with that solution was I had also reversed the OT wires during the same session, so I'm not really sure which fix solved the noise problem,,,,but, its definitely gone and the OT wires are in the right spots now
I also experimented with a pot in the PI tail resistor location, and "think" I dialed in a sweetspot of 56K
SOLUTION: I replaced the tail resistor stock value of 10K with the new 56K value (anybody see a potential problem there?)
If you want to see anything that I haven't posted yet,,,just ask
If this hurricane doesn't blow the roof off of my house I'll try to get something recorded later this week.
THANKS to everyone for your support and guidance so far....YOU GUYS have helped to make this happen!
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Very nice amp . enjoy it.
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Nice lkooking build! Well done!
I like using a PI plate trimmer to balance the PI.I used one in a recent D style build and it is absolutely the S**T ! I can dial in serious tones.
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I'm going to be trying a few modifications in the coming weeks and I'll try to document them here...my goal would be to share EVERYTHING
OK, great! IF you want to really do that ............. here is a schematic that you can alter to share what you've done. I drew it up for you just for that reason alone. You'll need ExpressSCH to modify it.
:icon_biggrin:
With respect, Tubenit
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Nice work! :occasion14: :bravo1:
Looks great
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Looks great what schematic are you using?
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Thanks for the kind words guys....
Jeff, I have been inspired by your generous work here and hope to share what I have done and get help with tweaking the circuit to my taste....please bear with me while I learn how to use the Express SCH program
I'm currently trying to live through a hurricane and expect power to go out soon....real soon...winds are gusting to 60mph right now
cbass, here's the exact schematic I used, and I tried to stay as close as possible:
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Not sure where that schematic came from but its got a lot of changes from what I know as an express.
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while I learn how to use the Express SCH program
It's incredibly intuitive.
You can click on components and change the values of the components.
You can click on entire sections like a triode, LTPI, power rail, tone stack ................ etc....... and save an entire area. I have saved entire preamps, OD sections, reverbs, active FX loops, phase invertors, PT with power rails, tone stacks ............... and so on.
You can go into the "original library of components" (that comes with the program) and save the parts that you need like resistors, caps, filter caps, transformers, speaker, diodes, zeners, potentiometers, etc.............. all into a "FAVORITES" library.
They don't have a triode or pentode tube in the library of components, so I suggest you save the ones in the schematic I drew. Or draw up your own.
Almost any schematic you see me post is simply one I grabbed out of the Hoffman SCH Library of schematics and just altered. :thumbsup:
That's how I come up with them so quick. This Trainwreck was a single channel AB763 about 10 min before I altered it.
BTW, the schematic I drew is the one you referenced. They're pretty much the same. :icon_biggrin:
With respect, Tubenit
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Nice work Mr. Gun, Learning how to draw the schems is a must, makes it so much easier to see whats going on. I actually find it relaxing and when you find other circuits it is some times challanging to be able to link them all tohether.
"But isn't really what i was looking for" I'm hearing ya, I'm sure Tubenit & Co. must have a mountain of half built and rebuilt amp under there belts, I just copped it from the wife (after moving house)about the half built amps that i've got in the stashed in the cupboard.
But thats the drug where addicted too.Happy TWEAKING. :icon_biggrin:
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Lookin good Dave. Replace that 56k w/ a 150k or even >220k and you'll get more gain going into that last stage for more of what you're looking for. Also, a "true" wreck clone should have the Presence pot mounted further from the rest by itself, LOL! ;) Seriously, disenguage the thing (NFB/presence) temporarily and you'll see an improvement for more gain here too. You can get a switched or push-pull pot later on if you want. Anways, two quick & easy things to get more grind & gain going for ya. Good luck on the Storm passing by - did you put lamb's blood on your front door?
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Cool :thumbsup: :bravo1: :thumbsup:
K
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I'm going to be trying a few modifications in the coming weeks and I'll try to document them here...my goal would be to share EVERYTHING
OK, great! IF you want to really do that ............. here is a schematic that you can alter to share what you've done. I drew it up for you just for that reason alone. You'll need ExpressSCH to modify it.
:icon_biggrin:
With respect, Tubenit
Great schematic you sketch Tubenit, I should learn to ExpressSCH .To bad it is not for Mac . I should use my old PC
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Also keep in mind this circuit is prone to ultrasonic osicilations.If you have that going it won't sound very good.
Hows it clean up when you back the guitar vol. down?if its bright and jangly.You are probaly ok.
Hope the hurricane didn't hit ya to hard.
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If you are still having problems with the prescence circuit.Try mounting the NFB resistor right on the pot.Then you can experiment with placement of the NFB wire for the most stable spot.I'd run it right under the end of your turret board
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Thanks a lot guys.... woke up this morning and the roof is still on the house so we're okay.... running on generator power and there's no power at work... that's where the amp is.... I'll get back in there tomorrow and fire up the soldering iron
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Great schematic you sketch Tubenit, I should learn to ExpressSCH .To bad it is not for Mac . I should use my old PC
stratele52, old PC for ExpressSCH should work just fine, but if you want a Mac program you can try JSchem (http://dhost.info/jschem/ (http://dhost.info/jschem/)). It opens SCH files, but will only save to JSCH. I like it just as much as ExpressSCH and use it on my Mac.
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OK...power is back on and I'm not at work so I had some time to mess with ExpressSCH....the first thing I did was adjust any incorrect values, or values I have changed, to bring it up to date.......and you were right Jeff, it's very easy to use......
In the Paint version I have included an idea for a first real modification, to utilize the unused triode V2b....I can't stand to see those 3 pins with no wires going to them,,,especially if I'm asking for more gain......let me know if there is a "better" idea than the cathode follower....also let me know that my drawing is correct/incorrect
Took a minute to cut and paste some stuff in Paint so that guys that aren't using E SCH can join in:
**UPDATE**- this master volume idea was a horrible waste of time , but I'll leave it up for reference
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Not sure where that schematic came from but its got a lot of changes from what I know as an express.
Schematic came from page 7 of this PDF: (kinda cool because there are a couple nice variations to try there)
Only problem is that his idea of the meanest amp is not the same as mine....
Presence circuit is OK now, and clean sounds are really good, and definitely get better as you decrease guitar vol.
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a "true" wreck clone should have the Presence pot mounted further from the rest by itself, LOL! ;)
I knew I could count on you to lighten this up.....yeah, I left the knob off in hopes that I wouldn't insult anyone
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Spent a little more time and was able to transcribe Paint jpeg to SCH file, which now includes possible mod1...
Let me know what you think tubenit.......it takes a little getting used to, but very cool FREE program....at least this way we're carving the same type pictures into the cave walls :icon_biggrin:
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OK, let me toss out some thoughts and observations and considerations.
The Trainwreck has two fairly high gain stages going into a more "relaxed" 3rd triode with no cathode cap & with lower gain PLUS a grid resistor dropping volume in front of that. Note that the Trainwreck uses 22uf cathode caps on those first two gain stages.
So you kind of have two very cranked gain stages into a very low gain stage.
The Dumblish amps use 4 moderate gain stages in series.
In contrast to that, the Dumblish amps tend to use 5uf caps (or maybe 10uf on a few models) in those first two gain stages going into OD stages also with 5uf caps. In the OD stage, the coupling caps are reasonably small. I also have seen a BadCat type preamp and OD schematic that had some low cathode cap values & low coupling cap values between gain stages.
I think you will find a very difficult time getting a clear non-muddy tone by adding another gain stage with those first two cathodes having 22uf caps. That's my unscientific opinion from experimenting. I think you'll get grit and grind but will lack a sweet musical harmonic tone.
I think the cathode follower that you've added will change the original tone but will not increase the gain at all. That's my guess. Having said that, I built a Double C amp for a friend sort of doing what you are doing. A triode into a triode into an OD stage with a triode with a cathode follower (this Double C amp is in the ExpressSCH Library for you to look at)
So in my thinking, IF you actually want to increase the gain by adding another triode gain stage, I think you're going to have to significantly lower the cathode cap values on V1-3 & V1-8. You might be able to use 10uf on V1-3, then 5uf on V1-8 & then add something like the Dumblish OD section with 5uf or 2.2uf cathode caps.
I also think you'll need to lower the .1 coupling cap into the LTPI to a lower value like .002 to .01 range.
Anyhow, those are some of my thoughts. My guess is the 22uf caps will just give you high gain mud IF you add a triode gain stage and don't lower the 22uf values. And too high of coupling cap values in the OD stage will give you mud also, IMO.
With respect, Tubenit
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I want you to take a close look at these 3 different high gain preamps (& OD).
What do you notice about the size of the coupling caps between stages?
What do you notice about how volume/gain is dropped by resistors and/or pots between stages?
What do you notice about the size of the coupling caps with 3 gain stage amps compared to 4 gain stage amps?
Ponder that ............. and then post what stands out to you about increasing gain on amps with varying gain stages.
Remember ........... IF you really aren't going for a Trainwreck amp tone but simply want a GREAT amp tone that is actually perhaps
innovative and cool sounding .............. you have alot of options to consider to make this your own design. (sort of)
With respect, Tubenit
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OK, let me toss out some thoughts and observations and considerations.
Thanks buddy,,,that's what I'm looking for....I appreciate you taking the time to guide me
I'm definitely into the Dumble stuff and will evetually head in that direction 100%
I'll start slow and try to document everything and hopefully get some recording done at each stage of mod. so you'll be able to hear what we're doing.....there's only one big problem that I'll try to fix in the next week,,,I don't really have any good speakers..I sold my 4x12 w/ vint.30s and haven't replaced it so what you hear will be coming out of some cheapo Celestions I have laying around...I figure that if I can get a decent sound out of those, then it should sound great with some new G12H 30's or something like that
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What do you notice about the size of the coupling caps between stages?
What do you notice about how volume/gain is dropped by resistors and/or pots between stages?
What do you notice about the size of the coupling caps with 3 gain stage amps compared to 4 gain stage amps?
I printed that out and will be staring at it for the next 1/2 hour.....
This is the part that I really NEED to understand....I know that.
Coming from welding machine repair, I thought this stuff would be easier, but with tube amp circuits, it seems like the more I learn, the more I need to learn.....in my spare time I'm still trying to digest IMPEDANCE
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OK, .......... just to continue to stir your thinking (and I am NOT handing you a script ........... strictly to get you to think creatively).......
Again, I am keying off your idea of a high gain amp that doesn't have to sound like a Trainwreck but that sounds really good.
IF I was given the task of trying to have 3 gain stages that were clear OD tone and NOT muddy, I might consider something like this.
1) paralleled V1 triode for 30% more gain with no floor noise increase
2) very low insertion loss tone stack
3) a 250k trim pot instead of 56k resistor to ground
4) switchable NFB on/off
5) you will have to experiment with coupling cap values and cathode cap values where I show a range to consider. I would NOT use any
cathode cap above 10uf. I personally would try the lower indicated values first and then increase IF needed.
6) 250p smoothing cap
7) 120p enhance cap on the LTPI plate resistor
8) I think there is a chance the volume pot would need to be lowered from 1M to 500ka
Again, I am not suggesting that you build this but thought I'd toss it out to demonstrate something a little outside the box that might sound pretty cool. So I'm not trying to give you an amp design but instead inspire you to think creatively but with reason based on observing what others have done successfully.
So IF you came up with something like this that sounded great, then you'd have something that would be pretty unique. I've looked at ALOT of schematics and haven't seen anything that had this same topology and approach.
With respect, Tubenit
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I think jojo meant the change the 56k resistor on the third gain stage going from the grid to ground.
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I think jojo meant the change the 56k resistor on the third gain stage going from the grid to ground.
Thanks cbass, I'll check with jojo on that one....it does seem like an awfully high value for that PI position
I obviously have some more reading to do...
Ahhh yes, I see it now....he say's "going into that last gain stage"........rookie :think1:
I went back and fixed the jpeg, hopefully before anyone else saw it :icon_biggrin:
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OK, .......... just to continue to stir your thinking (and I am NOT handing you a script ........... strictly to get you to think creatively).......
Again, I am keying off your idea of a high gain amp that doesn't have to sound like a Trainwreck but that sounds really good.
Great stuff there T,
I am going to have to do some more reading so I can catch up.....this is not a one time fling for me at all and I really must understand this stuff to move forward...
I don't care at all about keeping the TW circuit in tact other than keeping the one aspect that I did fall in love with which is the amps tendency to jump into harmonic feedback very easily when cranked (mine does do that)...it was my understanding that the higher value bypass caps in the first 2 stages were partially responsible for that,,,,and if I have to live with a little mud- that's ok
BUT, that's not saying I'm not listening.....I WILL try lower values in both positions, one at a time, and record their effect
I do want to keep it a simple circuit, and it really doesn't sound BAD as-is, I just want it to sound more bad-ass
I'm interested in learning, and the good news is, I am not in a hurry to have a completed amp.
The minute I "finished" this amp and plugged in,,,I knew it wasn't finished
Thank you so much for your help
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OK, a couple more simple ideas to try.
1) PAB (preamp boost) - try simply disconnecting the bass to treble pot connection, if you like that put a mini-toggle there
2) try a .03 cap for the mid cap in the tone stack. Simply use insulated alligator clipped wires to parallel a .01 w/.03. I find the .03
reduces some mid tones that make an amp sound muddy.
3) try reducing the .1 cap into the LTPI to .047 or .02. Unsolder one end and "clip in" a .047 or .02
4) add smoothing cap and especially the enhance cap (82p- 120p range) Again you can (SAFELY) clip on those caps and try them
5) undo one end of the 22uf cathode caps and clip in 10uf on the V1 Clip in a 10uf or 5uf on the second gain stage
6) reduce 47k to 33k or 27k input resistor
7) paralleled triodes in V1
8) you can try a 68k slope resistor which will increase gain. You can clip in a paralleled 330k to get a 76k value there and try that
9) clip in a paralleled 82p - 180p range cap across the 500p treble cap. This definitely
will give you a gain/overdrive increase
Easy things to try in an effort to improve tone and/or increase gain. Keep working with the amp until you get a "WOW" factor going.
With respect, Tubenit
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I would really like to start with a master volume because my old ears cant handle the volumes that this thing sounds best at...
What do you think of my original mod for the cathode follower master?.....how about that cap value I inserted?
Do you consider a master vol. a LAST step once you have the amp "voiced"?
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heres some ideas you could try.
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I would really like to start with a master volume because my old ears cant handle the volumes that this thing sounds best at...
What do you think of my original mod for the cathode follower master?.....how about that cap value I inserted?
I would be inclined to try a PPIMV master volume, but what you have there is OK if you like it? The PPIMV would allow the phase invertor to still be "cranked" and (I think) do a better job at preserving the high gain tone.
The CF is fine & I think it will simply change the tone and do nothing significant for gain. Try anything from .001 to .01. I'd probably start with .0047.
With respect, Tubenit
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heres some ideas you could try.
Thanks again cbass, I cant open that file with E SCH
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Sorry I have know idea on how to change the file type. :dontknow:
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I would recommend the ppimv also.Really an attenuator is the best way to tame these amps.Some folks like vvr but I've never tried it.
I think you can see it now.I tried to make the values red where there are changes.I added a high cut control and a fast gradual switch like on the comets.I find them very useful however YMMV.The CF doesn't add any gain in this situation. But it causes compression I think
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The cathode follower master would cut down the signal going into the phase inverter (PI) so that both PI and the power tubes operate in the cleaner range. The PPIMV would allow you to cut the signal after the PI, i.e. it lets you hit the PI hard. The side effect is that the presence control will not work as well when the PPIMV is turned down, due to the fact that the feedback loop decouples if it does not get enough signal. If this bothers you, change the 5k pot to a 4k7 resistor, keep the 0.1uf cap there and add a cut control like Vox AC-30 (I learned this from Larry aka novosibir).
EDIT: cbass already posted the idea with the cut control.
Tubenit posted some very good ideas. I especially like idea no. 2.
Cheers Stephan
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6) reduce 47k to 33k or 27k input resistor
It feels like I'm hitting the front end extremely hard and I was considering increasing the input resistor value.?...I assume that will reduce the front end "spank" I'm getting??
I was also going to suggest to others to use low output pickups with this design....all of my stuff is high output, but I haven't tried the '57 classic+ in my LP yet
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The CF doesn't add any gain in this situation. But it causes compression I think
That's a good thing...this thing could use a little compression....it sounds and feels very raw to me
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It feels like I'm hitting the front end extremely hard
I think the 22uf cathode caps contribute significantly to feeling like it's being "hit hard". At least that has been my experience. I quit using 22uf caps yrs ago. I think they made my amps sound muddy/gritty/grainy.
When I first starting building/designing amps (all the way back to the Carolina Blues Special), I used center off spdt switchs on the V1-3 cathode with paralleled caps. I found that I preferred 2.2uf, 5uf or 10uf and consistently disliked the tone I got with 22uf caps which sounded harsh to me. I never could get the clarity on my amps that I wanted with 22uf caps. I began looking for (& found) other ways to increase gain/overdrive without increasing grit. I like smooth gain.
My guess (& I could be totally wrong) is that a 27k input resistor with a 5uf cathode cap would give great gain without a tone of sounding like it's hit hard?
And that may not be the case?
With respect, Tubenit
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OK here's the breakdown for tonight...I'm gonna keep it simple, and keep the board as in tact as possible...
1) I'll record sound clips of the amp AS-IS
2) Experiment with lower value cath. bypass caps in both V1a+b ( I dont have many "in stock" values, so I'll have to try what I have (2.2uf maybe?)
3) I'll increase the value of that 56K going to ground before V2a grid (i'll try a pot and see if i can dial it in)
4) Wire V2b as pictured above for a cathode follower to feed pre-PI master (save the PPIMV for later)
5) Try the PAB and install a switch if I like it
6) Clip in a 100pf cap parallel with the 500p treble cap
7) Clip in enhance cap around 82K PI plate resistor
8) Fix the incorrect wiring of my Cliff input jack
9) Record more sound clips in hopes that I improved something
Maybe not in that order, but I'll try to take my time and see what each change brings to the table....I can't say thanks enough....stay tuned
Unfortunately, I work a little slow :sad:...amp is at work and mods don't start until 5:01 EST
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All of those sound like a very good plan. I look forward to hearing and hearing of the results.
Experiment with lower value cath. bypass caps in both V1a+b
IF you have limited cathode caps and values & can only lower one of those than lower V1-b. Maybe try a 2.2 in V1-b and listen. Then parallel a second 2.2uf for 4.4uf on V1-b & listen again.
With respect, Tubenit
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On my lunch break I took some V ac-dc readings...just for the record
This is where we stand: Input is 124 vac...sec. is 340-0-340...rectified and filtered B+ 480vdc to plates(higher than I had anticipated)
470vdc to screens...-45vdc bias on pins 5....bias at idle reads 18mv, with cathode resistor method...running 2 new Tung sol 6V6 and they don't seem to be bothered by the 480v
I had some old EL 34s in there and I expected them to sound better, but they really didn't, plus they increased the clean headroom, which really isn't what I'm looking for here, I like the lower output and perfect breakup of the 6V6....plus they hurt my ears less
I experimented with a Variac on the input and took it down to 105vac input, which lowered the B+ to 410, which was my target, and I cant say I heard a huge difference...it did seem to make the amp feel slightly less stiff....maybe even "brown" :dontknow:
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All I can say is WOW!!!! :blob8: :happy1:
Talk about bringing an amp to life!!!!......so this is what you guys do in your spare time
I am having more fun in the last 2 hours than I have had in the last 2 years.....some changes bring monumentus leaps in improvement while others are subtle, BUT, it's all coming together....
Once I got past being afraid to mess up my beautiful board, I have found the secret to the tube universe....this thing RIPS
I'll be back with the results, I'm keeping great notes, but I could do this for days....only problem is my ears can't take anymore, so I'm gonna take a minute and wire the master in, which will probably bring about another wave of changes.......
If you see my wife---tell her I love her..................this could be awile
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All I can say is WOW!!!!
Cool, sounds like you got it into the "WOW" zone!
I have found the secret to the tube universe....this thing RIPS
Man, your enthusiasm is remarkably fantastic! Congrats! You got me chuckling pretty good with the "secret to the tube universe" line.
:l2: :l2:
If you see my wife---tell her I love her..................this could be awile
:l2: :l2:
Looking forward to the review and notes. With respect, Tubenit
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And then the master volume crashed the party......0 out of a possible 10....really bad :cry:....it figures, because it was the only thing I added to the design......all of the magic is gone unless you turn it all the way up, which obviously defeats the purpose, and even then it sucks tone and sounds like crap.....boy, tonight is an eye opener.....guess what I'll be doin for the next half hour??....it's coming out!!!
T, everything I tried before this was WIN, WIN, WIN, WIN....I'm not gonna let it get me down......not every idea is a good idea...that's one of my favorite sayings
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I have the PPIMV on the D'Mars OD Special and like it alot. I think it maintains a good tone down to about "4".
Glad some of the other mods to try were useful.
With respect, Tubenit
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Guys, let me start by thanking Tubenit AGAIN for your his help....without your timely posts, "suggestive reasoning" and true directing skills, I would not have had the confidence to try everything that was on my list last night.....I had a "breakthrough" experience, and it helped me accomplish something that I had wanted to do for years, and that alone is priceless.....THANK YOU!
You other guys know who you are and I really appreciate all of your input.....the fact that you guys take the time to help people you've never met still surprises me and inspires me to do the same....THANK YOU!
-I started by attempting to record some sound clips which was a total failure, and I apologize, because you guys deserve to hear what we've accomplished here,,,I'll work on that
-The first big changes came as I started to experiment with the bypass caps on V1a+b...I first disconnected the 22uf on V2b and tried it like that:
reduced gain, less harsh sounding, reduced bass response, reduced cool feedback effect,,,didn't like it.
-I then inserted a 1uf in it's place, and got a significant mid boost that sounded much better than having no cap there, but brought back some harshness, and was still lacking the bass response I originally liked
-Then just to go to the extreme, I disconnected both bypass caps at the same time and BLAH!!.....flat, lifeless, but the ability to feedback was not totally gone, which led me to believe that not all the magic is in those stages (that was an important lesson, because I had assumed it was)
-So then I reversed the previous values and put the 22uf back on V1b while switching the 1uf over to V1a....now we're on to something (unfortunately I was limited to those 2 values in stock here so I stopped there)
-The results made me play guitar for about 10 minutes with a huge smile on my face....I saw the light!!!
-The front end harshness was no longer an issue...it felt like a "real" amp now..it had ok gain and nice punchy upper and lower mids that just rounded out the whole tone beautifully...the feedback was more controllable...it didn't feel like I was wrestling with feedback anymore
-Feeling like I was halfway home I decided to leave those 2 caps in those positions and move on to that 56K resistor going to ground before V2a that jojo had originally mentioned.....MAN, DID THAT EVER LIGHT THINGS UP!
-I inserted a 250K pot in there and dialed it in , and it was literally like having a dial-up-distortion control....I sat there for 5-10 minutes just trying to dial it in and of course wound up on the high side, settling down at 220K, where it just seemed RIGHT...I also went back and experimented with the bypass caps again, but the values I had originally settled on were the best.....right about now, my ears are telling me to cool it, so i took a break and tried the master vol. idea i had posted
-I wired it just as I had drawn it in the schem. and it couldn't have been any worse...horrible, waste of time, tone sucking, useless, but a good lesson...let's leave it at that ,,,,it's gone now, never to return again
-I tried the PAB mod by disconnecting the wire from the mid pot to bass pot, and it didn't make much of a change, but it did make for some flabby/muddy bass, brought back some harshness, so I reconnected it and liked it better like that
- I then clipped a 100p cap parallel across the 500p treble cap, and it gave it a nice treble boost (I couldn't believe the change), but it wasn't the direction I wanted to go and it made me question if i want to reduce the value of the 500p that's there......next session
-Then I tried the enhance cap, and again, couldn't believe the difference that made....I clipped a 100p parallel accoss the 82K plate resistor in the PI and it made a very ODD change...it added an almost clanky/honky effect to the OD tone and when i turned the vol. down on the guitar it added an effect similar to the sound of the piezo pickup on my Parker.....hard too describe,,,but not useful in this instance
-Last but not least I tried my resistive load attenuator, and that also acted a TONE SUCKER,,,it did it's job but also took away a lot of nice top end and a lot of favorable feedback and speaker interaction...but it has done that with every amp I have tried it on, even though the author says it wouldn't...here's the plans for that attached:
That's it for now....back at it tonight with a different guitar....and another attempt at recording
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I say Bravo to you, and all the souls who help with this awesome endeavor. I absolutely love this!
Great job. Can't wait to hear it! :bravo1:
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Glad it's more to your liking. I've tried a lot of different things with this type of circuit and that schematic I posted is very close to what I found to sound the best out of all the things I tried.Its basically a komet concorde.
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Glad it's more to your liking. I've tried a lot of different things with this type of circuit and that schematic I posted is very close to what I found to sound the best out of all the things I tried.Its basically a komet concorde.
thanks again for your help....as I was deconstructing the master volume debacle I completely disconnected the cathode follower circuit, so I never stopped to listen to it in there without the MV pot....it looks like that's the biggest difference between mine and that schem. right now
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Since I'm in the market for speakers and a master volume, I'd like to know what you guys think of this:( skip to 1:45 to get through talking)
Eminence FDM Reignmaker Speaker (http://www.youtube.com/watch?v=BJP2PosH9fk#ws)
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Great schematic you sketch Tubenit, I should learn to ExpressSCH .To bad it is not for Mac . I should use my old PC
stratele52, old PC for ExpressSCH should work just fine, but if you want a Mac program you can try JSchem (http://dhost.info/jschem/ (http://dhost.info/jschem/)). It opens SCH files, but will only save to JSCH. I like it just as much as ExpressSCH and use it on my Mac.
I put expressCH on my old PC .
I just read your post now. I going to look JSchem for Mac. Thank's very very much
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Since I'm in the market for speakers and a master volume, I'd like to know what you guys think of this:( skip to 1:45 to get through talking)
I think you could do that and spend the money and then reach around the back of the amp and dial the speaker to lower the volume ...............
OR use a $5 PPIMV on the front of the amp & switch the pickup selector to a different pickup to change the tone.
With respect, Tubenit
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Great schematic you sketch Tubenit, I should learn to ExpressSCH .To bad it is not for Mac . I should use my old PC
stratele52, old PC for ExpressSCH should work just fine, but if you want a Mac program you can try JSchem (http://dhost.info/jschem/ (http://dhost.info/jschem/)). It opens SCH files, but will only save to JSCH. I like it just as much as ExpressSCH and use it on my Mac.
I put expressCH on my old PC .
I just read your post now. I going to look JSchem for Mac. Thank's very very much
I just download JSchem for Mac , seem to work . Now have to learn and practice.
Thank's
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Good see you're alive SG, and a crazy amount of good progress too! Maybe you can call this amp "Sandy" when you're all said and done!??? ;)
I would like to keep suggestions down to you for a bit since everyone's throwing so many out there already as it is and you're going through a great learning process that's got to be done. People that just take suggestions but do nothing on their own aren't really learning by doing and substituting...it's a process needed to fully get a handle of things and interactions of components and values.
What I would say is d/l Merlin's Load Line Plotter Xcel spreadsheet when you can. This will help to understand gain, shelving response, etc. as it relates to components and tubes used in your designs. 2nd - cbass showed you his comet-ish design, notice the split load made into a pot control??? That's exactly the kind of thing I was describing to you on your other preamp that cuts down signal w/out using high end reducing voltage dividers but sometimes has to have bypass caps to make up for....more components, slightly different responses, gain altering effects, etc...that doesn't necessarily need to be/have.
What kind of MV did you install, I can't seem to find it on anything posted?
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OR use a $5 PPIMV on the front of the amp & switch the pickup selector to a different pickup to change the tone.
You really have a way with words.....I get it.......my wife thanks you
But I still do need 2 speakers to fill this verticle 2x12 with open back top 1/2.....was thinking about Celestion G12H30 (70th Aniv. model),, but I hear they are made in China.....I really want to move up to Alnico but it hurts my wallet just thinking about it
There needs to be a better way for guitarists to demo speakers.....nothing sounds good through my computer speakers
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What kind of MV did you install, I can't seem to find it on anything posted?
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People that just take suggestions but do nothing on their own aren't really learning by doing and substituting...it's a process needed to fully get a handle of things and interactions of components and values.
What I would say is d/l Merlin's Load Line Plotter Xcel spreadsheet when you can. This will help to understand gain, shelving response, etc. as it relates to components and tubes used in your designs.
I couldn't agree more, and most of the reason I never took it this far before is because I knew I was unsure about what I was doing and didn't want to just take chances....now that I feel more confident I can continue to experiment with what you guys have given me so far and just continue to report back on my results...and keep reading and trying to digest this stuff........I kinow a lot of it just comes with experience and I'm lucky I have this background with welding machines, so at least I won't die trying stuff!....thanks for pointing out the Merlin spreadsheet and I know I need to add one of his books to my library....I've already noticed that I have a fundamental difference of opinion with Gerald Weber,,,,because I DO like preamp distortion
I would describe the current sound I am getting as heavy Angus Young when the Vol. is on 3 and guitar volume on 7...and then it gets much more aggressive and reminds me more of early VH/ Zep on steroids as I increase both volumes....I'm really liking the current sound and hope to get it recorded for you guys soon
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Search for Larmar master volume you should be able to find a diagram
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If you like preamp disto then you like dumble/boogie-type amps and many newer ss/tube amps like JCM900DSLs and the like? Most anything new and commercial has ss in it "w/ distortion pedals built in". Even the Dumble ODS amp has a jfet input for increased overdrive front end push. They aren't necessarily "bad" either but there are purists and there are others that go where they need to get what they want. Pedals/pedalboards don't have to be a bad thing - they enhance and provide diversity. Then you have "pedal purists" - some hate opamps and only like jfets or vice versa, lol but I digress. Sorry to blab about on your thread. I just keep thinking of your Neal Schon tone you're after and you may need or want to consider some of these things in addition to your amp for the final outcome??? But until then, lets keep having as much fun riding the tube as possible.
ps - I also like riding other tubes too! ;)
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If you like preamp disto then you like dumble/boogie-type amps and many newer ss/tube amps like JCM900DSLs and the like? Most anything new and commercial has ss in it "w/ distortion pedals built in". Even the Dumble ODS amp has a jfet input for increased overdrive front end push. They aren't necessarily "bad" either but there are purists and there are others that go where they need to get what they want. Pedals/pedalboards don't have to be a bad thing - they enhance and provide diversity. Then you have "pedal purists" - some hate opamps and only like jfets or vice versa, lol but I digress. Sorry to blab about on your thread. I just keep thinking of your Neal Schon tone you're after and you may need or want to consider some of these things in addition to your amp for the final outcome??? But until then, lets keep having as much fun riding the tube as possible.
ps - I also like riding other tubes too! ;)
That's it,, I'm moving out there....it sounds like we're drinking the same Kool-Aid :wink:
I am not a politician so this is easy for me:
" I don't care what it takes to get this thing to sound right".....if you told me to put a SCR bank in the PI and pulse the output, I'd do it
I'm no purist, and although I would like to stick to tubes for this build, I was going to approach you with the idea of a build that had switchable effects built in,,,,,similar to the Bogner Alchemist.......I don't see how a touch of analog OD would be bad....except I have heard some modern amps that I couldn't stand the sound of because of the fizzy or fake sounding distortion
I don't want pedals on the floor just because I'm sick of the whole excess baggage thing.....if I had a gig next week there would be pedals on the floor and unfortunately I'd be playing out of a Boogie....the dream would be 3 switches on one pedal on the ground- clean, OD, lead- done
I've been playing Boogie for 20 years, I really don't have much experience with anything else, BUT the Dumble thing is on my bucket list and my "to do real soon" list........I'm also a huge fan of the Gilmour tone......talk about rambling on and on and on......
I sound like a guy who needs to build a couple more amps :icon_biggrin:
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:laugh: I've got a Boogie Mark IV but don't play it much...you'd like the footswitch. (shussh, it's got ss in it too)
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Here we go again....in tonight's round of tweaking I doubled back over one of the results of last night, and questioned the treble cap...
I tried lowering the value to 250p,,,didn't like.....tried raising it (a lot) and put in a .0047uf and messed around with that and what I found was that I really liked that but only if the treble pot was turned down to 1-2.....what did I just do??....I tried a .001uf and then just jumped back to the .0047 because it just seemed to "have something"
:help: I might be losing my ears, because of back to back nights tweaking.....
Is .0047 too high a value for that spot?
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T, here's another one....
I think I might like the gain further downstream in the signal...
Any problem with paralleling V2a-V2b, partially for the simplicity of it because I already have the unused triode THERE, but partially because I already seem to have enough front end gain??
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I think paralleling V2 is fine. You may need to lower the cathode cap value? Also I have found with paralleled triodes that I prefer 5751 tubes over the 12AX7s.
I like it that you are trying stuff out and figuring out what works best for you and what doesn't work for you! Excellent and I appreciate your sharing your findings.
Regarding the .0047 treble cap. Consider using a .000__ (whatever value) in series with _______ value on a spdt switch to get options of .00__ and 500p. (The 500p would be the final result of those two in series). Use one of the internet capacitor in series calculators to play with values. Pay attention to whether your preference is with BOTH chords and lead guitar work or it varies such as 500p with chords and .0047 with lead guitar.
With respect, Tubenit
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Had to walk away for tonight....need new ears :sad:
Here's the results:
-Paralleled 3rd stage coupling cap .001 with an additional .001....sounds good- I miss it when it's not there---maybe more full mid gain that way
-Took treble cap all the way up to .0047uf and loved it but only with pot rolled back to 1-3...not 0 ( way too harsh over 4 )----the only drawback is this stuff is bringing back some front end gain---but, in a better sounding way......I'll mess with the bypass caps again tomorrow
-Had to decrease value of bias resistor to 10K to be able to get less neg. voltage from circuit to increase bias to 22mv (ma).....(bias pot was maxed out with 15K in there )
-Tried a cheap 2.2uf elec. bypass cap in place of the 1uf on V1a and didn't like the change in the eq bump ( I may have just heard the difference between a cheap cap and a good one....cheapo 2.2 was old radio shack, 1uf is Solen..250 v version)
What cap do you guys prefer for cathode bypass?
Thanks again for your help...unfortunately no recordings yet (crappy built in mic on digital 4 track can't handle input signal, and clips if I look at it wrong...p.o.s.)
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Really could use some speaker suggestions from the high gain classic rock guys.....not metal...looking for smooth breakup, not loud, liquid lead tone
Wish I could afford one of those Eminence Black Mountain......or Celestion gold/blue.........too many choices
What do you think about that Weber 12A125A for this application jojo?......I remember that was your choice for the TOS....this is a different amp?
I have 2- 2x12 cabs to fill
Duke of Earl says Weber Legacy.....cone type?---dustcap type?
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The 12a125a 20w or 30w Weber speaker is very close to a Celestion Blue IMHO. I also love an Eminence Red Fang. I have both in cabs I switch back and forth with at the moment. I also have Celestion Blue in my 10w SE EL34/KT77 amp which sounds terrific (perfect application here). Celestion Gold needs to be pushed so if you're using for a lower watt amp, you're better off w/ a Blue. But for gigging/playing out then a Gold may be the ticket? I also have Heritage G12M & H's & also V30's too for specific apps. These just have that certain something ya know? Eminence is good too but I always end up going back to Celestions for some reason for many things. Weber's Blue Dog's sound great in 10" 30w but for 12" I'd suggest not going to a higher 50w or greater and don't like the Silver Bell by themselves, they need to be paired w/ a Blue Dog. Stay 30w or lower for 12" models to get that chime or sparkle. Spiders, coil sizes, and cone types w/ or w/out treatment really do matter much more than the dust caps do. I have a special fondness for all the Weber curved seam cone speakers for their woody ready tones and the blue pup/dog cones in general no matter which series of speaker you decide is in your budget. I haven't tried any of the Legacy speakers yet.
I love a speaker to be clear warm and present for most apps. except when soloing w/ high gain - then you want to back off the treble/tone controls for that super smooth high gain lead sound...you don't want sizzley, gritty, coffee-grind buzziness here...but for spankin' cleans it's a different story - for me anyway. It's hard to describe but clean transparent touch sensitive that will absolutely take your pants down if not playing correctly kind of tone which really brings out your chording and guitar's tone woods kinda sound for cleans...then it's the other opposite spectrum side for stinging singing melt your face off kind off lead tones...sort of Santa-ish (or Schon). Those are my personal fav's or signature tones for the two extremes. It helps to have a friend that's a Celestion US sales manager also. :icon_biggrin:
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Thanks jojo,,,good stuff there....
I'm just gonna have to take the plunge and try something....
There seems to be a decent market for slightly used speakers on eb@}.....so if I dont love it, at least I can get rid of it and try something else
It's just such a matter of taste, I understand I just have to sac up and open the wallet :cry:
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Big night tonight, back to tubenit's list...
1) Will parallel V2 and experiment with separate bypass cap/resistor on V2b cathode and maybe add a bypass cap to V2a while leaving V2b unbypassed, and experiment with the bypass caps on V1 and their relation to what I do on V2
2) Adjust grid stopper value(still have a pot there) feeding V2, while experimenting with bypass cap values
3) Experiment with lower coupling cap value feeding PI
4) Try NFB switch
5) Put EL34s back in and bias hotter than before and listen
5 1/2) Make a decision and order a speaker! :BangHead:
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Silvergun, have you checked out warehouseguitarspeakers.com they have alot of British speakers! They have sound clips for all of they're speakers. Just a thought, William_G
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This is the ppimv for fixed bias type of master volume control you want to use when/if you get around to it.
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have you checked out warehouseguitarspeakers.com
Thanks W G...just did...I like their prices, but I'm not one to buy "no name"(sorry) brands.....no insult meant, just never heard one
Since I have to buy them without really hearing them, I gotta go with something proven
Really leaning towards Avatar's Hellatone G12H30 $99....maybe mix with a Weber Legacy???...I don't know.....somebody shoot me
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This is the ppimv for fixed bias type of master volume control you want to use when/if you get around to it.
Thanks jojo, do you believe in it?
That is a GREAT pdf!
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Here's the current schematic.....for anyone who is keeping score:
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Nice, I was wondering where you were with everything. When you start stating trying stuff on V this and V that I get totally lost what you're doing.
additional suggestions:
1- change input resistor to 33k
2- try changing V1a load resistor from 100k to 220k to see how this affects your gain through to your vol control.
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Thanks AGAIN,
I keep adding gain, which I like, but I've noticed that the amp gets really loud now down around 3 on the vol. pot...really don't even turn it past 5
Is there a way to keep the gain (OD), but reduce the signal (amplitude?) getting to the power tubes, even before the PPIMV?...or will the PPIMV circuit do that inherently? ( meaning-- is there a little signal loss just by having the PPIMV there, even if it's turned all the way up? )
Now that I think about it, the volume increase came after I increased the bias (of course it did )....and the 6V6s are breaking up too much now....I'l crank it back where it was...actually I'll just throw the EL34s in and see how they sound now
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is there a little signal loss just by having the PPIMV there, even if it's turned all the way up? )
Anticipate that with the PPIMV turned up that the volume is the same as with 220k resistors to ground. PPIMV works well for me and preserves front end gain without the power tubes being too loud for me.
With respect, Tubenit
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-Feeling like I was halfway home I decided to leave those 2 caps in those positions and move on to that 56K resistor going to ground before V2a that jojo had originally mentioned.....MAN, DID THAT EVER LIGHT THINGS UP!
That's a handy little mod to keep in mind on many amps. Changing that one resistor (but going from 1Meg to 330K on R9 in this case) will transform a Peavey 5150 from a beehive into a really nice hard rock amp. Not only will it warm up a under gained amp it will tame an overly aggressive amp, too.
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Here's tonight"s results:
-Put the EL 34s in there and biased them to about 34mA and although the amp was louder and cleaner there was no noticable change in "tone" for the better so I reverted back to the 6V6s and re-biased them back down to 18mA,,,because I want those tubes in THIS amp, for me, I like the lower wattage...
-Played with PI coupling cap and found that by going down to .022 there was a little too much overall sparkle reduction, but raising that to .047 was a great compromise and as I went back and forth between the stock .1 and that .047, I preferred the latter,,,it seemed to introduce a nice low mid enhancement but retained enough sparkle, so I left it...
-Tried and definitely confirmed tubenit's theory that it is more favorable to use a lower value bypass cap on V1a, then higher on V2b, and now added a still higher value on V2a which was previously unbypassed.....as it is now I have changed it to 1uf on V1a; 2.2uf on V1b; 22uf on V2a and this is the best combination of stage to stage boost that I have heard so far...
-Experimented and confirmed the fact that a higher value input grid stopper resistor DOES make the input "softer" feeling and is useful in taming high output pickups that feel like they are hitting the front end too hard.....I went as high as 100K and as low as no resistor and because I was using a Seymour Duncan JB bridge humbucker I wound up at 56K, for me, for this amp, which may also chage if I switch to a lower gain tube in V1.....I see how that resistor can really be a personal touch, and now I can appreciate having high/low inputs, or just making it switchable...
- The amp is currently "out of control", but the coolest part, and the part I was most interested in enhancing is the amp's ability to drive/jump into instant controlled feedback that turns harmonic....that is does, and therein lies the future
-If someone who truly had experience with amps showed up at my bench tomorrow I am quite sure they would say "WTF are you doing?"......but I am now the mad scientist and there is no turning back :blob8:...I could always just revert back to that ho-hum thing I had last week---NO WAY
- I am having a Beck's Oktoberfest (or 6) with my dogs tonight in celebration of a very sucessful week tweaking, and surviving Sandy, thanks to the help of my new "mad scientist" friends....my wife is lovingly starting to refer to you guys as "THE CULT"
DISCLAIMER
***All of this experimenting has come at a price,,,YES, I have built an overdrive machine,,,BUT, I have also created a NOISE machine that has a volume control that I can't really turn past 4.......I'm OK with that because I'm still trying to "voice" the amp, and I don't care how much noise I have to endure to get to the final result,,,,BUT if you build this circuit as I have done so far, be prepared for a wildly screaming beast, that you WILL have to tame......that's the next step, and I'm hoping that someone will step in and explain how to balance the gain by either compressing the signal or reducing the amplitude(?) before it hits the PI.....I am considering a lower gain tube in V1 and will probably just try that as part of the experimentation stage....I am also going back to the books and video instruction, but nobody really tells you how to cure "Abby Normal"
Mel Brooks' Young Frankenstein - "Whose Brain Was it?" (http://www.youtube.com/watch?v=yH97lImrr0Q#ws)
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I have also created a NOISE machine that has a volume control that I can't really turn past 4
IF you have all the volume you need, then you can change the volume pot to 500k or 250k? Don't get mentally hung up that it has to be 1M & dialed to "7". If you have the volume/gain you need with 500k (or even 250k), then you can reduce the pot volume.
Be sure to measure from the wiper to ground & wiper to side terminal that's not grounded PRIOR to switching the 1M pot out.
Let's say for example that the 1M pot on "4" is 280k to ground from wiper and 720k from side terminal to wiper. Now when you switch the 1M pot out for a 500k, you dial the 500k pot to 280k to ground and you only have 220k from wiper to side terminal. So, functionally it is actually possible for the 500k to have as much or more useable volume. The reason for that is that 220k will allow more signal to pass thru than 720k (wiper to side terminal). And going from 720k to 220k there may possibly allow the amp to be more touch sensitive at that volume. At least, I have found that to be the case on one amp.
Now a good way to experiment with this would be to use alligator clipped wires and clip a 1M to wiper to ground. Now experiment with dialing it. Does it go closer to 6 or 7 before it's too loud? If so, then maybe a 500k pot will work for you there?
Hope that explanation makes sense to you? I have a 500k volume pot on the D'Mars OD Special and only dial it up to between 4-7 at the most.
OF course if you use a PPIMV, this may allow you to crank the 1M volume pot and still be OK. It's like a see saw and everything has to be considered in balance.
With respect, Tubenit
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IF you have all the volume you need, then you can change the volume pot to 500k or 250k? Don't get mentally hung up that it has to be 1M & dialed to "7". If you have the volume/gain you need with 500k (or even 250k), then you can reduce the pot volume.
Ah Ha....of coure I knew that :think1:
In welding machines we don't change the value of a pot, we just replace them because they get broken off by guys we like to refer to as "neanderthals"...
But, of course that makes sense and I really should've been able to figure that one out.....you just saved me MORE time!!
I'll put that one on the top of the list for next session.........THANKS AGAIN,,, AGAIN!
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T,
I had an idea after I logged off tonight.......may not be a new idea, but might be a good idea I have never thought of before:
Build the gain stages around 1 specific guitar, if you know that's the guitar you'll usually use through THAT amp....
I would assume that most amp co.s make amps to accomodate ALL types of guitars and therefore,,, make compromises
It is my understanding that a certain value bypass cap basically give you a gain boost at a specific freq. and above,,,,,
I'm thinking that if you look closely at the freq. curve of your pickups, and choose the value of your bypass caps specifically to enhance or round out those frequencies, and then narrow down--- at what point in the gain path do you want those freq.s re-introduced,,,could add WOW factor!? right?
Think specialty amp......not necessarily versatile amp...one trick pony built to match what's on the other end of the input cable :thumbsup:
Even though I'm sure that approach is not news to everyone here here, I want you to know that the bulb is lit on this end.....might not be the brightest bulb............I have a feeling that the freq curve of the 57 classic+ pickup in my LP is going to help me to choose bypass cap values to try............ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ :offtheair:
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Here is a non-technical way I look at the volume/gain pots. The value used will react in the same way when you changed the 56k grid leak resistor to a 220k and you increased gain by raising this value. Why? Because it's in parallel w/ the signal output tube's plate resistance of the prior circuit which has an effect on signal gain going into the next stage and causes loading effect just like tone stacks do to a signal. It is also a simple voltage divider but, by lowering this value down to 500k from 1M and using tubenit's example you are going from having an effect of 720k as a grid stopper to the next stage (using the 1M pot) to only 220k (using the 500k). So naturally since your signal is going through much less resistance of the 220K value you will not lose nearly as much high end (& clarity of your signal) and likely may not need a treble bleed for the pot as a result like you would using a 1M pot. This is why I stopped generically using 1M volume/gain pots some time ago.
Another thing SG is if you have a lot of signal that needs to be cut down, another option available to changing as above from a 220K/56K grid leak resistor, rather than using a voltage divider - use a split-load resistor set-up and this will also preserve your high end and drop your signal output at the same time. So if you have too much signal coming from the last stage for example and don't want a MV pot or whatever you want to call it (pre-phase inverter volume which I think you did before?), change the load resistor from 100k to using 68k & 33k resistors and taking the signal output from between them to your p.i. and you'll drop your signal down to 67% or use 82k & 18K = 82%, etc. however much is needed to make you happy.
Report back when you're re-energized, lol. :laugh:
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Try tacking a 33k resistor across your 100k plate resistor on the second stage.That will tame it down without killing highs.You can try different values too. If you don't likeit easy enuogh to take out.If you do like it then you can incorparate the split load switch
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Thanks c and jojo,
I'll put that stuff on the list....really priceless stuff you guys are giving me here at the perfect time!
8 full hrs. of yardwork today,,,,, and I'm itchin to get back to the amp,so I'm going back over some posts and I'm going to try some things that I haven't had time too........I really can't wait to try the PPIMV, just gotta place an order for the dual gang pot,,,and some different bypass cap values......what is the lowest voltage rating that I should be using there?
And just so you guys understand where I'm headed with this.....the goal here is to create a lead guitar monster, without compromise to any cleans or crunch, just pure liquid enjoyment that I will use via an A-B switch with B being "NITROUS"..."A" will be the tame one with the separate clean and crunch channel....maybe a TOS or Tweed BM ,etc, etc...
I'm trying to build a sound that I've been dreaming about for 30 years.
2 heads on top of 2 - 2x12 cabs on stage, maybe this spring, in a souped up dance/rock band ....fun.....when I step on "B"--LOOK OUT!
:m1
Another thing SG is if you have a lot of signal that needs to be cut down, another option available to changing as above from a 220K/56K grid leak resistor, rather than using a voltage divider - use a split-load resistor set-up and this will also preserve your high end and drop your signal output at the same time. So if you have too much signal coming from the last stage for example and don't want a MV pot or whatever you want to call it (pre-phase inverter volume which I think you did before?), change the load resistor from 100k to using 68k & 33k resistors and taking the signal output from between them to your p.i. and you'll drop your signal down to 67% or use 82k & 18K = 82%, etc. however much is needed to make you happy.
Exactly what I need exactly when I need it, thanks a million jojo!
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c,
This is the part of your schematic that I had originally breezed over, mainly because i didn't understand the benefit of the switch there...I assume it's just a switchable gain boost...I needed that explanation from jojo so my 2 brain cells would start rubbing together again..
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I stopped in Radio Hack over the weekend and picked up some different value non-polarized electrolytics for bypass cap experiments...
So back to it tonight, here's the agenda:
1) Split load resistor experiment at each gain stage.....(does it make sense at each gain stage or should I just focus on the third (V2a)?)
2) Try different bypass cap values in all 3 stages.....2.2, 4.7, 10uf
3) Try 33K parallel across 100K plate resistor on 2nd stage (per cbass)
4) Change Vol. pot value to 500K from 1M
5) Change treble pot value to 100K from 250K
6) Parallel V2a+b and experiment with separate bypass cap on new V2b, or just give it a separate unbypassed cathode
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c,
This is the part of your schematic that I had originally breezed over, mainly because i didn't understand the benefit of the switch there...I assume it's just a switchable gain boost...I needed that explanation from jojo so my 2 brain cells would start rubbing together again..
Yes thats the split load switch.One postion cuts the signal the other is 22k+82k so its pretty close to the stock value.
When its in the 22k position it cuts the signal and should make the amp more controlable. In the other position it will be close to what you have now.
Sorry I'm not very good at explaining stuff
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Sorry I'm not very good at explaining stuff
You shouldn't have to be....I'm sure there's times where this feels like "Tube Amps 101" and I apologize for that.....
I really appreciate you guys hangin in there with me throughout this process, and I don't want you to think that I'm not listening.
Maybe once we get over this hump and I get some more reading AND hands on experience under my belt, this won't be so painful, and you guys won't have to walk me through this simple stuff,,,,and I'll even be able to contribute......
It is a little embarrasing to learn everything OUT IN THE OPEN LIKE THIS......I've never felt dumber and smarter all at the same time :undecided:
cbass,,,who's the guy in your profile pic?....I always feel like that's the face I'm talking to.....it's a little intimidating....he's always looking DOWN at me
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You've never seen dumb and dumber?Thats Sea Bass.As in "kick his ass Sea Bass"
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Got it...can't believe it's been almost 20 yrs. since I saw this:
KICK HIS ASS SEABASS (http://www.youtube.com/watch?v=J_y_tQMtnYo#)
If you care to share,,,go here and give us the story behind cbass:
http://www.el34world.com/Forum/index.php?topic=14249.0 (http://www.el34world.com/Forum/index.php?topic=14249.0)
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Results from last night are in:
-The biggest thing I learned is that there is a lot of noise associated with adding a bypass cap to the third stage...I tried a few values there and would up with 1uf.....I shortened the test leads that I was using to experiment and that helped with the noise and the Solen cap I used there also seemed to help, but there is definitely lower noise if I leave that stage unbypassed,,,and I'm very happy with the stage to stage values at this point
-I have not paralled V2 because I already have plenty of gain= too much volume
-I replaced the 1M vol. pot with a 500K and didn't get a significant volume reduction....it's my assumption that with the volume control that early in the circuit, I'm not going to get a desireable result by simply changing value there.....I imagine the PPIMV is the answer I've been looking for,and I finally ordered the pot from Doug (along with a couple of those nifty little relay boards)
- I wired in the split load resistor mod on V2a, in 2 dfferent value combinations,,,the first time I tried 51K and 51K splitting off in between the two resistors to feed the reduced signal to the PI, I didn't get the significant reduction I was looking for so I split it again, this time using 18K to an 82K to plate, and although I did notice a difference, it wasn't enough for me to leave it there....(again, looking forward to PPIMV)
-I soldered a 33K parallel across 100K plate load res. on V1b and did like the results (increased audible OD),,,BUT question the math, which I am unsure of....
I believe by doing that I have reduced the value of those resistors in par. to 24.8K....is that safe? or reliable?....(I need to read more)
I took a couple of minutes and soldered up some short test clips which now "hover" the components over the board,,,here's a pic
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That's starting to look like my new creations when I'm initially done. Well done lad.
That third stage isn't meant to be bypassed. It is a sort of soft clipper biased into cutoff. If you change the 10k resistor then you're changing the intent and sound of the design (whether you care or not?) But there's other benefits for this like helping to get rid of thin buzzy hot biased pre stages occurring before it, helping w/ parasitics/oscillations, etc. You biased very hot w/ the 33k accross the 100k plate load causing tube to go into saturation/grid current limiting. You go, crazy man!!! As Jack Black would say I want my face to start melting from the screaming lava leads coming outta that thing. :laugh:
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You biased very hot w/ the 33k accross the 100k plate load causing tube to go into saturation/grid current limiting. You go, crazy man!!! As Jack Black would say I want my face to start melting from the screaming lava leads coming outta that thing. :laugh:
How long should I expect that tube to last being run that hot?
I'll try to do some recording tonight while it's still spewing lava and not melting
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-I soldered a 33K parallel across 100K plate load res. on V1b and did like the results (increased audible OD),,,BUT question the math, which I am unsure of....
-This was written as a mistake...I had actually put a 33K across the 150K plate load resistor of the second stage (V1b)...it's still there and will be until the tube melts (no red plate yet)***UPDATE- this has been identified as a bad idea, and was a mistake.....I will remove it and not wait for the tube to melt***I also adjusted the schematic to reflect the change back to the original plate load reistor value of 150K***
Tonight's results:
-I paralled V2a+b with a shared cathode and added a 1uf bypass cap in series with a 10K boost limiting resistor on that cap..
I'm making adjustments "on the fly" now and just sticking with what I like.....all the results are just better versions of wicked!
-I started messing with values in the tone stack tonight, and realize that I'm gonna need more time....everything sounds very punchy and strong, with big harmonics and pounding, howling low mids....only problem is upper mids/treble is just tooooo brittle/ bright/ piercing------I need help figuring out how to smooth out/ roll off highs
-Amp is much quieter now that most add-ins are hardwired in now
-Inserted a 250K pot in slope resistor location and dialed in, but couldn't decide so I left it back at 100K until I get back to that tone stack
-I attempted recording again but this signal is just crushing the input on this cheap 4 track i'm using-FAILED
Updated schematic:
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I had a revelation of sorts on the way to work today.....
MAYBE,,, I keep making changes to boost this and boost that, but never really change the volume setting on my amp...I just turn it off, clip in the adjusted value (cap/resistor) and when it sounds "better", I leave it in and continue on.........
The amp has continued to get louder without moving the volume control,,,just by making these adjustments...(boost, boost, boost, boost,,,basically + honestly)
MAYBE, it "sounds better" because I'm hearing a boosted freq. range that I would of heard sooner if I would've just increased the Vol. control setting......
I'll wait to get the PPIMV in there before I go further regarding volume.......tone stack tweaking is next
I'm also starting to think that it might be time to start thinking about getting what I want out of an amp,,,from a different design......
I had a friend stop in here yesterday, and he loves it as-is....he agrees with me that it sounds very much like a live Angus Young (AC/DC) rig, with the guitar vol. rolled off a little, but just gets ridiculous (good) at full guitar vol.
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Opps nevermind I see you don't have a bright cap
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That .002 cap across the volume pot will make the volume come on very fast.have you tried it without any brite cap?
I guess I don't have a brite cap,, :rolleyes:,,, but I have experimented with the cap value that "feeds" the treble pot...
Originally it had a 500p there, but I "thought" I liked the higher value (.0022).....I could go back to 500p and re-evaluate, and maybe make smaller incremental adjustments......that whole tone stack area will be under fire tonight
That's one of those "boost" mods that I did while throwing different values around, and at 1 point had it up to .0047.....that's about the time the vol. pot stopped making much difference...
I know that my old ears are letting me down a little, by needing more high end to "sound better".....but when I play out of the amp, it feels and sounds extremely brittle from high mids all the way UP....open chords and mids/low-mids/bass sound and feel excellent........even the guys in my shop walk by and say it sounds great, and they are a bunch of no talent ass clowns
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when I play out of the amp, it feels and sounds extremely brittle from high mids all the way UP
I think the paralleled triode needs the values changed out ..... or to go back to a single triode? I think those values are creating some brittle tones for you.
And you may need some smoothing caps (plate to cathode) like we use on the TOS.
You might try that "enhance cap" again once more using around 82p - 120p across the LTPI entrance plate resistor? It has been successful on every amp I've tried it on. Maybe you've changed enough that it would work now?
Originally it had a 500p there, but I "thought" I liked the higher value (.0022).....I could go back to 500p
You can have both by using a relay or mini-toggle and putting caps in series.
With respect, Tubenit
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SG, this design isn't going to give you the overdriving preamp distortion lead tones you are seeking. But I do have a suggestion or two for you to where you don't have to scrap the whole thing. Atleast the poweramp section. If you're interested PM me and I'll get more specific because it will require several emails going back and forth and I'd also like to keep from having too many cooks offering too many suggestions & opinions confusing things further.
For now - I'm curious for you to try something please? Will you try using that last triode set-up exactly as the third triode is designed in the original schematic? You will therefore be cascading those last two gain stages but the last one is important to use the 10k cathode resistor unbypassed/without a cap on it. Don't forget to put a coupling cap & grid leak resistor between the two stages. Let me know.
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I think the paralleled triode needs the values changed out ..... or to go back to a single triode? I think those values are creating some brittle tones for you.
I agree, but I'm unsure of the math,,,I read a little but it's confusing.....one thing I read was to cut the value of both the plate resistor AND the cathode resistor in 1/2.....but I did like having that bypass cap in there, AND Merlin talked about that "boost limiting resistor" that I have in series there and it did seem to work well at limiting the gain that I received from having that bypass cap,,,,,and made it desireable ( I just don't know how that affects the math either)...........also, it would be very simple for me to remove the paralleled "jumpers" from those pins, and try it again without the additional triode.
I like the idea of the smoothing caps and will take a look at that schematic.
My ears have been taking a beating, so I think some of these "enhancements" are blending together for me.....one mod into another (if that makes sense)
I am most grateful for the fact that you have stuck in there with me throughout this process....thank you again for taking the time from your to-do list
to watch over me and provide encouragement....I am listening
I have a friend who is a great player stopping by tonight and bringing his JCM800 head....we're going to put them side by side through the same speakers, and then I'll truly know where I am......I really wish I could get this damn 4 track to sound decent :BangHead:
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SG, this design isn't going to give you the overdriving preamp distortion lead tones you are seeking.
I am starting to get that feeling, and that's OK...I have time, patience and motivation.....I HAVE TO get better at this.....sadly, it's one of the only real ways I have fun right now......this is something that I've waited a long time to do and I don't expect to get it perfect the first time
For now - I'm curious for you to try something please? Will you try using that last triode set-up exactly as the third triode is designed in the original schematic? You will therefore be cascading those last two gain stages but the last one is important to use the 10k cathode resistor unbypassed/without a cap on it. Don't forget to put a coupling cap & grid leak resistor between the two stages. Let me know.
Yes I will....maybe not tonight, unless my buddy doesn't show up,,,but I'll put it at the top of the list
I (almost) have all the parts to do an equivalent of this amp,,,so if it's replacing the preamp board, that's cool,,,if it's a totally NEW design, that's cool too
I'm not going anywhere, and I want you guys there when I figure this out.......we've only just begun
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Big fun last night....my friend BOB stopped by wearing his rockstar leather jacket and carrying a Marshall JCM800 model 2205- 50 watt head (EL34s), and a very nice stock Gibson SG....I told him to hook up and play at stage volume and give me the real deal...he did, and here's the results:
- This amp has a great midrangy punch that immediately set it apart from the amp I am working on, and I was worried, because this setup really sounded awesome, and I knew he would be plugging into my amp soon.......he had the gain cranked to 8, the channel vol. on 8, and the master on 2, which after a little knob twisting,,,, I too was convinced that this was the best settings for his type of playing (Zep, Sabbath, VH, Guns and Roses, AC/DC, etc, etc)
- We switched him over to my amp and the difference was obvious,,,,we now had much broader low-mids/low freq. response, but the 6V6s were not handling the load, and were breaking up very easily (which was the original intention for using them).....so I decided right away to switch them out for EL34
- I put EL34s in there and re-biased to 35mA, and the result was very real......now we had more headroom, clarity throughout the spectrum, and although this amp didn't have the mid punch of his amp,,,,,,my amp DID have something that his didn't......it stood right up to one of the best rock amps out there, and that felt GREAT!
- We experimented with different value bypass caps, and settled on these:
4.7uf on V1a; 4.7 on V1b; 1uf with the boost limiting resistor still in series,,,,,and that was the clear winner.....it got rid of a lot of the mud that Tubenit was trying to tell me all along.......I thought it was going to kill the bass response, BUT it didn't and that's a lesson learned
- With the vol. on 3, treb. 7, mid 5, bass 6, presence 10, we found the sweet spot, where it would bark, bite, growl, sing, and especially feedback into harmonics, which he enjoyed as much as I do....
- I broke out the Variac and lowered the input Vac to 105 and it brought the B+ down to 395Vdc....I rechecked the bias and adjusted it HOT to 51mA, and that combination was a pure winner.....he got a huge grin on his face and wanted to place an order right then and there
- Although I originally liked the sound of his amp better,,,,after some adjustments we both actually preferred the sound and potential of mine
-The volume was very similar with both amps and he said he could use mine onstage...
- I asked him for comments, critisizm and he asked for a little more gain :l2:...which made me laugh out loud because it has a ton of gain
- So from here I'm going to continue to voice the amp based on these findings and just try to narrow it down to a great sound with THIS circuit....
I'm going to try jojo's cascade suggestion, tweak the tone stack values, install PPIMV, and basically STOP trying to get this amp to sound totally different than it was intended..................I can wait to get "MY SOUND"
- When finished I will label this amp the "HOME-WRECKER", sell it to Bob, and use the money for parts to move further along towards the dream...
- He asked me for an amp that will "put some blonde PU$$? on (his) lap",,,,,so that's where HIS head is.....and I can appreciate that,,,mine will be trying to figure out how to get an amp to do that...........Now that would be a marketing slogan :icon_biggrin:
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Glad you are making progress with the amp and you & your friend are enjoying it. I appreciate knowing the lower value cathode caps did help with transparency and clearing up some mud (at some level) in the TW design & topology. Thanks for sharing that.
Will you try using that last triode set-up exactly as the third triode is designed in the original schematic? You will therefore be cascading those last two gain stages but the last one is important to use the 10k cathode resistor unbypassed/without a cap on it.
I think Jojokeo is giving some good advice to try. This is a reasonable approach. I like the 10k without a cap on the 4th stage cathode idea.
Something to consider regarding Jojokeo's sound advice.........
I will say that my D-style inspired amps typically will use 100k and/or 250k pots in the OD section. Having said that, I actually have some very low values to ground in those pots. Particularly going into the OD section of a D-style amp (which would be the 3rd gain stage, I may have a "trim" pot that is only 22k-27k to ground?
I am thinking the 3rd gain stage may need a fairly low resistor to ground value and then you can bump up the value in the 4th stage. In other words, maybe try a 68k-120k resistor to ground on the grid into the 3rd gain stage and then try that 220k into the 4th stage. I am thinking using 220k into both of those will be too much gain and even bring possible oscillation?
Maybe Jojokeo can comment on that approach?
Work with Jojokeo on the topology and values. He has alot of experience and knowledge about designs & mods. And I think he may have a much better understanding of the direction that you're wanting to go & the tone you're after. (which I am guessing is different than the D-style amps?)
With respect, Tubenit
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I just stopped in for a quick read and update and everything sounds real positive. I'm outta time so I printed out the latest schem w/ comments so I can go over later today. Great feedback SG & info as always T!
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Will you try using that last triode set-up exactly as the third triode is designed in the original schematic? You will therefore be cascading those last two gain stages but the last one is important to use the 10k cathode resistor unbypassed/without a cap on it.
I think Jojokeo is giving some good advice to try. This is a reasonable approach. I like the 10k without a cap on the 4th stage cathode idea.
Yeah, I put this mod on the top of this list right now.....I want to try it before I insert the PPIMV, so that I don't confuse results
I am thinking the 3rd gain stage may need a fairly low resistor to ground value and then you can bump up the value in the 4th stage. In other words, maybe try a 68k-120k resistor to ground on the grid into the 3rd gain stage and then try that 220k into the 4th stage. I am thinking using 220k into both of those will be too much gain and even bring possible oscillation?
I understand 100% and will leave the (variable grid leak resistor) 250K pot before V2a, and put one before V2b, and attempt to dial in a great "blend " of gain by adjusting those 2 values........
Thanks again for the idea to use that approach, it gives me the "mad scientist" feel that I am now embracing.....and trying not to abuse
When I get a chance I will update both JPEG and SCH shematics
Next steps: (possibly tonight)
1) Cascade V2 a+b per jojo's advice and experiment with grid leak resistor values
2) Tweak tone stack
3) Install PPIMV
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OK, I looked up the settings that are my "favorite" tone on the D'Mars ODS. This favorite tone is more of an overdriven sustaining clear tone than a high gain tone. I am intentionally avoid grit/grind and looking for smooth sustain. So I presume you're going for something with more grind, but at least, this illustrates the concept. And I can easily dial in almost endless sustain in the same amp but with different settings on OD drive and OD level .
OD trim (50k set at "6.5") = 49k to ground prior to 3rd gain stage
OD drive (250k set at "4") = 29.4k to ground prior to 4th gain stage
OD level (250k set at "3.5k") = 18k to ground post 4th gain stage
These settings are such that there is no volume difference between the clean and OD channels (at the volume I like to play). Just a difference in tone, overdrive and sustain.
PPIMV (favorite setting for volume) is 66k to ground.
My guess is that you will want more gain and volume than I do? And if so, simply up the values. Anyhow, this gives you a reference point to be thinking thru this.
With respect, Tubenit
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Nice....thanks T,
I always appreciate your playing and tone and I definitely hear what your talking about there...I have been enjoying your soundclick page since I came aboard the forum,,,,,and you're right....I would want more gain and grind in my amp, and I'm actually still sitting on a TOS board that I WILL eventually build (it'll just be a TOS TURBO OD)....this TW thing sidetracked me, but I'm glad I did it because it is such a simple circuit, and lends itself well to experimentation...
Here's the projected schematic for tonight's work for you and jojo to look over and make sure I'm translating what he's suggesting for the cascade mod:
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Schematic looks good to me. I think that could be a very nice amp. Hopefully, Jojokeo will add his perspective. I think he's got a better grip on the tone that you're probably after.
I would be tempted to also try a .02 - .047 coupling cap into the LTPI instead of the .1. However, that may not be needed & could be tried at another time.
With respect, Tubenit
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I'll quickly say sound advice from T on the grid leak resistors. You may want to solder in a 22k - 47k or something between ground and bottom lug which allows you to turn pot completely down. Not a must but keep you from gounding the signal out. By the low .002uF coupling caps btwn them it would be easy to parallel these quickly to adjust the frequency of signal getting through too giving more low mids, etc.
Lastly, try a higher value on the V2b's cathode also such as going as high as 39k like Soldano does on his SLO 100 amp. The reason is to give you a feel for what this does as being a soft clipper effect.
Looking forward to results...an maybe a listening test one of these days????
My other suggestions are more radical from a circuit design point to what you're doing right now (meaning changing the circuit as it currently is set-up and requires a partial re-build of the front stages) but since the amp's already wired up the way it is, these last adjustments are easy to do while in it's current configuration. It may or may not need further reconstruction at this point and the only way of knowing is manipulate that circuit?
In reading your prior email about Bob's visit, which was quite entertaining BTW, you talked about how his amp sounded. You too could easily manipulate yours to sound pretty much exactly the same way fairly easily. That's the great fun of these simple circuits using tag strips/eyelet & turret boards...so easy to re-design things for anything you want it to be. Same thing when using vero board when I'm building effects pedals. The old painstaking way of making circuit boards is long gone.
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I'll quickly say sound advice from T on the grid leak resistors. You may want to solder in a 22k - 47k or something between ground and bottom lug which allows you to turn pot completely down. Not a must but keep you from gounding the signal out. By the low .002uF coupling caps btwn them it would be easy to parallel these quickly to adjust the frequency of signal getting through too giving more low mids, etc.
Lastly, try a higher value on the V2b's cathode also such as going as high as 39k like Soldano does on his SLO 100 amp. The reason is to give you a feel for what this does as being a soft clipper effect.
Looking forward to results...
WOW :blob8: :happy1:...lit it up again!!!!
Wired it up point to point (cause I ran out of board), just like I drew it up and WHAM!!!.....face melting, lava spewing, blonde on your lap, smokin' hot TONE.....
This is just a preliminary report,,,,BUT----GREAT BALLS OF FIRE----
I'm sill tweaking grid leak pots, and so far I've only raised the 3rd-4th stage coupling cap to .0047,,,and V2b cathode at 33K,,,,,but I just had to let you guys know what we've done here is INCREDIBLE!!!!.....stay tuned...MORE LATER
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:laugh: Nice character drawings (multi-talented)!!!
IF you have a tiny bit of high end roll off needed, insert small value grid stopper going into 3rd stage first, then maybe 4th stage's input 2nd. By the Miller effect & input capacitances this will roll off a bit of high end for you (just a little theory of why). Also with grid stoppers you help prevent blocking distortion too when used later in signal chain.
Lowering the 100k slope resistor in tone stack may give you a slightly fatter sound/signal as you experiement w/ the tone stack. But every value change made to the tone stack affects the freqrency response of your controls. If you need more low end from the stack increase the middle cap from .02 to .047 or more likely 0.1uF. Not sure what you're liking or maybe lacking right now in this area but two considerations for the tone control tweaking for you w/out guessing. One last note is that these will mostly cause only a change in control settings but not necessarily be like a "leave it or remove it" type of deal like what you've been doing. Meaning instead of Bass set to 6 and Mid set to 5 as before, you may get the same response now w/ Bass set to 3 and Mid set to 4 at the same high volume? But at lower playing settings you may need more bass signal on tap which you'll have available then. So what I'm trying to say is that you can always decrease control settings but it's much harder to increase bass frequency for example if it's not there in the first place and you want the best sweep/range of your controls for various playing levels. Hope this helps? Just a reminder as you are likely aware already but on final tweaking it's best when using actual speaker(s) and/or guitar(s) you'll end up using OR use various guitars & speakers if going for more universal/versatile (you said earlier that you were using a crappy speaker just laying around?)
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increase the middle cap from .02 to .047
1+ That's what I do and usually use .03
With respect, Tubenit
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IF you have a tiny bit of high end roll off needed, insert small value grid stopper going into 3rd stage first, then maybe 4th stage's input 2nd. By the Miller effect & input capacitances this will roll off a bit of high end for you (just a little theory of why). Also with grid stoppers you help prevent blocking distortion too when used later in signal chain.
Cool,,,I didn't even think of ADDING a grid stopper at either one of those locations, but I will experiment with that next.....
I was looking at the 820R going into V1b as a possible candidate to change, but wasn't sure of what effect it would have...
I tried tweaking the tone stack and noticed exactly what you guys are saying...no huge changes, but just different "ranges" in the tone pot settings...
I'll go to the .03 on the mid. cap
At this point the amp is a 50 watt distortion pedal....so with that comes hiss, and feedback, but I'm glad we took this route, because I feel like I'm at the top of the mountain, as far as gain (OD) is concerned, and now I can work my way back and start addressing issues....
I'm also glad it went this way because I feel like I was able to "voice" the amp before adding that last gain stage and now we're just amplifying/overdriving what was already a good sound...
Here are the biggest problems I need to address next:
1) I have to do something about the preamp volume , and I'd like to do it before I install the PPIMV so I'm not mixing results (will the V1b grid stopper effect the vol. control much?)....I will really concentrate on this tonight and go back in the posts and try to follow what you guys were telling me about pot values ( I tried replacing the 1M vol. pot with a 500K, and when that wasn't an immediate improvement, I put the 1M back and moved on)
2) There is a "screechiness" in the strings when I slide my hand up or down that has been there all along but is just more pronounced now that we have more OD/volume...standard "pick slide" type screech that just seems to really jump out at me.....( I realize that comes with the distortion territory, but I wonder if it's a certain frequency that we can cut).......and maybe it's got something to do with my guitar which has a Seymour Duncan JB, no tone control/cap and just has a 500K vol. pot (Bob's stock SG sounded better)
3) Just noise in general...adding that 4th stage has amplified the bad as well, so I will need to go back and re-flow some solder, check lead dress, check ground connections, and wire paths, plus make some permanent components out of those grid leak pots on V2a+b......etc,etc,etc
If you couldn't tell from my last post,,,I am extremely excited about the sound coming from this amp now!......even through this "crappy" Line6 labeled Celesetion I am using......Bob said the speaker sounded OK to him, so I guess it's not the worst
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It's Alive! Alive!......
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so with that comes hiss, and feedback,
Shielded cable in the right places.
Try moving wires safely with non-conductive chopstick. Sometimes that will significantly change hiss or hum. You may possibly be able to dramatically lower noise doing that (sometimes)?
Try different tubes.
Try "enchance cap" (again) across LTPI entrance plate resistor. I actually found this to not just eliminate high end "hash" BUT instead it actually increased blooming where notes tend to blossom and open up more with greater sustain. It may work just great this time after these recent changes?
Try snubbing caps 220p-390p range on the 3rd & 4th gain stages from plate to cathode.
Remember on changing the 1M to 500k, that you can put a resistor going into the non grounded side terminal of the 500k pot. The idea of the 500k is to "mentally" have the volume on "7" instead of "3". It's more of a mental thing really in that regard IF you're using a resistor into the 500k. Hope that makes sense.
With respect, Tubenit
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Remember on changing the 1M to 500k, that you can put a resistor going into the non grounded side terminal of the 500k pot. The idea of the 500k is to "mentally" have the volume on "7" instead of "3". It's more of a mental thing really in that regard IF you're using a resistor into the 500k. Hope that makes sense.
This is making a voltage divider along with the pot which lowers the overall signal down even when the vol is full up/on, but also cuts out some highs too w/out a treble bleed/bypass cap on it to make up for it (if you need the highs back?). This will lower your preamp volume you've been complaining about and you are dropping signal in a permanent way as we've said earlier in this post and similar to the split plate load techinique remember? If the resistor is designated R1 and the pot is R2 then the formula for voltage out (when the pot is on 11) is Vin x R2 / R1 + R2.
Noise level...where have you run the center tap of your heater wiring? Anything further you will need to show a good picture of the complete inside of the chassis? A doctor can't treat a patient unless they make a trip to the office.
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Even more fun today...went into work on one of my days off (which I never do, unless it's to be with this amp)
Got lucky today and it was a big one:
-I soldered a 50K trim pot in series wtih the 820R grid stopper coming off of the vol. wiper to V1b and went all the way up to 51K and it just plain sounded better...
-I had also put a 10K trim pot as a grid stopper before the 4th stage V2b and dialed that to 2.7K
That combination was awesome and it got rid of some of the preamp "spank" I was talking about early in the build, and added a great feel to lead playing, plus a slightly "vocal" mid voice that just kills....
-Got a little crazy and replaced the 250K grid leak pot before the 3rd stage (V2a) with a 1M!......I could dial that all the way up and it just got better.....I couldn't believe the killer distortion and the fact that it wasn't really getting muddy or lost, but REALLY filling out the low mids/bass....BAM!!......left it at 800K!
-Those 3 tweaks has this thing sounding more and more like the 1st VH album tone (+ extra dirt),,, I know a lot of people have tried a lot of things to get close to that sound, and I believe that you could dial in those 2 grid leak pots and nail it ...........
the amp still sounds good when you turn the guitar vol. down, but I wouldn't really call it clean anymore, but's it's got a nice "crystally" pushed grit, that would definitely cut a mix
-So, since I was starting to bleed from my ears,,,, and I didn't want to do anything else different to the preamp.....................
I FINALLY INSTALLED THE PPIMV---AND IT IS A WINNER!!!!!---it aint coming out!!
It sounds good throughout the entire range of the pot, BUT still sounds best at full volume, with the control all the way up (of course it does)........but there are plenty of useable settings from 3-8, with everything from bedroom vol. to a decent practice vol.......
YES, it does thin out at the lower settings but who cares...it still sounds good and it's the only MASTER that I've tried that actually retains the aggression of the preamp. :thumbsup:
- I played more "casual" guitar today then I have in 7 years since I "retired", because the amp is a joy to play,,,,and it probably sounded like I was auditioning for a VH tribute band.......I'm thinkng about it :wink: :bs:
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Noise level...where have you run the center tap of your heater wiring? Anything further you will need to show a good picture of the complete inside of the chassis? A doctor can't treat a patient unless they make a trip to the office.
I've got 2- 100K resistors (artif. CT) coming right off of the indicator light housing AC tabs to a ground tab 1/2 inch away
I think my noise issues are a combination of issues, incuding, but not limited to:
Temporary pots still wired in as grid leak resistors (and just hanging over the side of the amp)
Wires from tube sockets (added gain stage) overlapping and crossing...
Possible cold solder joints where I "rushed in" multiple mods...
Amp being opened up and me sitting within 1 foot of it while playing...
Temporary mini (bias type) pots wired directly to tube pins as grid stoppers...
A lack of shielded wire in critical locations.......
A crappy guitar cable...that is usually on the floor over the AC input cable...
An old un-shielded/un-insulated Variac in my AC input path...
PPIMV basically just done point to point in mid air, and hovering over board (I wasn't convinced it was going to work for THIS amp...(man was I wrong)
A workbench area that is surrounded by flourescent lighting....
I need to clean up my bench :sad:, and then clean up this board :embarrassed:, and then talk about noise........after I'm done tweaking :wink:
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I've got 2- 100K resistors (artif. CT) coming right off of the indicator...
100Ω would work much better.
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Those wires & pots definitely make a difference to that noise for sure. Glad to hear the PPIMV is a winner there and seems like you're getting the classic EL34 crunch going.
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I've got 2- 100K resistors (artif. CT) coming right off of the indicator...
100Ω would work much better.
I think they are 100R and I just forgot (I know they are supposed to be).....it was a month ago that I put them in there, and I am getting old........thanks for looking out!!
But I will check them because I have made mistakes before.......
Hey,,,WHERE did you get that ohm symbol???....I want one
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Those wires & pots definitely make a difference to that noise for sure. Glad to hear the PPIMV is a winner there and seems like you're getting the classic EL34 crunch going.
Yeah,,,I won't know where I stand until I straighten this stuff up...
The EL34's were definitely the way to go with this one.......I didn't realize until I heard that JCM800
PPIMV surprised me.... :thumbsup:
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Hey,,,WHERE did you get that ohm symbol???....I want one
Alt 234
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where's the rest of the symbol key strokes?
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These?
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Thanks sluckey™
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+1 :worthy1:
Sluckey for President 2016 :wav:
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Updated JPEG schematic to include weekend updates....(sorry for the cut and paste BS, but it's simple)
PPIMV really smoothed this amp out and I much prefer it on 5 than 8, but that's only 'cause my ears are old...8 does sound better
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Here's a pic of the best drummer I ever had the honor of sharing the stage with ('89-'97) this pic is from New Years Eve 1995...this amp was partially inspired by his influence on me
When you hear me say that my ears are old / bad,,,it's all his fault....he used to break the biggest sticks you can buy on his snare because he liked the pop he would get when he would catch a piece of the rim.......
I couldn't figure out how to post this in a PM,,,so here it is,,,,he belongs on this thread with THIS amp
Mike Belton 1967-2009
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I meant to ask, what's with the 51k resistors after the wipers of the PPIMV? Dropping more high end?
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I meant to ask, what's with the 51k resistors after the wipers of the PPIMV? Dropping more high end?
I was gonna mention that....I put them in there because they were in your schematic from Mission Amps...(33K to 100K,,,it says....so I just threw 51K in there without any thought)
I tried it with and without them and it seemed to sound better without them, but I'm still a slave to the schematic, so I left them in...
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I don't know....can anybody tell me where all of this noise is coming from??? :l2:
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Use a lower ISO setting. This may be done by decreasing the shutter speed or increasing the f-stop settings, allowing the photographer to use a lower ISO. A lower ISO means decreased sensitivity of the image sensor, and so smaller electrical currents--the cause of ISO related noise--are not recorded.
Amp looks cool BTW - a bit messy though.
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I think he was being facetious :icon_biggrin:
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i was!
Thanks for the pic, Silvergun. I'm a few steps behind you as a mad scientist. More of an ill-contented Scientist.
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I had the opportunity to visit Silvergun's Laboratory last night. I thought i knew what gain sounded like. I've been playing guitar for over 20 years. I thought my AX84HO had high gain....I now know why they call it the brown tone. I almost shat myself. Killer Distortion and Singing Sustain. This Trainwreck killer is something.
Silvergun impressed me with his understanding of what you guys have been teaching him in this post. He kindly left his chassis open with the temp mods in place so i could hear the differences with the changes. I heard the difference in his amp with bypass caps in and out, as well as the variable grid leak resistors, Holy Gain Dial-In Batman! Thanks Silvergun- Your Awesome!
I didn't hear any DC noise on the pots for his grid leaks, could he tie them in as knobs? I would guess, as a nube would, that if he placed a small value resistor in series with the pot he could change the gain effect on the fly. Could that be used in place of a gain control?
But, I'm sure that if it could be done, it would have, by now...
-LLama :thumbsup:
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Probably the coolest thing that Llama and I did was to take the 12DW7 (7247) tube from his AX84HO and try it in my V1 position...(see attachment)
The way that this tube is configured with mixed triodes was something I was totally unfamiliar with........it allowed me to try a lower gain (12AU7) in the second gain stage while retaining the stock (12AX7) in the first stage.....(for those who are unfamiliar, THIS tube has both types of triodes in a single tube package,,,,,so I didn't have to put in a separate tube socket to try separate triodes and experiment with different gain values in those stages)
Are there many other tubes configured this way??
Well, much to my surprise, it worked perfectly with that tube in that position and allowed my (preamp) volume control, to actually have a useable range from 0-10, with 3 being a nice lowered gain sound, and dialed up to 8, right back to the the insanity I've come to know and love...( before this experiment, there was no reason to turn the control past 3, because all it would do was introduce more noise,,,,,OD was maxed at 3).....that revelation alone was worth the price of admission for Llama stopping by .
I had left all of the temporary mods in place so that I could expose Llama to "the mad scientist" approach of tweaking, and it's now time to make some things permanent, clean up the board, and then start looking at noise reduction.
If I can get something recorded I'll post it.............I have even more confidence in the amp after hearing Llama's comments :grin:
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it worked perfectly with that tube in that position and allowed my (preamp) volume control, to actually have a useable range from 0-10, with 3 being a nice lowered gain sound, and dialed up to 8, right back to the the insanity I've come to know and love...( before this experiment, there was no reason to turn the control past 3, because all it would do was introduce more noise
Thanks for sharing that! Great experiment and creativity in that.
With respect, Tubenit
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:l2: SG has a hype-boy!
Damn it all to hell...I've finished my schems for my latest creation but it was slanting towards the Plexi's CF>PA sections-direction. Now I'm starting to re-think :think1: my original idea of making both in the same amp. Damn you and thank you SG.
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Now I'm starting to re-think :think1: my original idea of making both in the same amp. Damn you and thank you SG.
Your East Coast R+D dept. (me and llama "the hype guy") says do the double preamp thing.....that way you can make it double bad-ass,,,that's better than single every time.......we both agree on that
Tubenit was asking about the possibility of stacked boards in a recent thread.......if you build it like that, you could build 2 separate preamp boards, and if it turned out to be unnecessary, just remove the one you like least and build another amp out of it :think1:
4 total preamp tubes (2 for the Wreck and 2 for the Plexi).....+1- EF 86 if you must
4 Channel amp with clean Wreck, turbo Wreck, pushed Plexi, lava Plexi
The Wreck tone controls don't make a ton of difference, so if you could just live with the tone stack bypass (PAB type - permanently), you could eliminate those controls ( I saw on your thread where that was a concern....i.e...# of controls)
I don't know :dontknow:.......sometimes I feel like a dumb little kid trying to tell his dad how to fix the family car
I'm also still not convinced that they sound different enough to justify the time...?
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4 total preamp tubes (2 for the Wreck and 2 for the Plexi).....+1- EF 86 if you must
4 Channel amp with clean Wreck, turbo Wreck, pushed Plexi, lava Plexi
The Wreck tone controls don't make a ton of difference, so if you could just live with the tone stack bypass (PAB type - permanently), you could eliminate those controls ( I saw on your thread where that was a concern....i.e...# of controls)
I like the sound of turbo wreck and lava plexi. I would've said that about the tone stack where it is in relation to it's set-up & design. The later in the preamp the better the control factor and often the difference btwn more of a rock sound, definition, & control to blues sounds. That would be a great blues amp like a tweed w/ pronounced mids and early break-up the way it is. (didn't we discuss this already?). I think you might be better served by cascading the first two stages, then tone stack and finally recovery and soft clipper. Better control, definition, and likely better tone too. This was what I was going to suggest much earlier on. If you're happy with it then why change it? But...if you're willing to re-build Frankenstein with Abbey Lutely's brain instead of Abbey Normal's then... in the name of science you will be compelled by your destiny to acheive your tubular zenith. :happy1:
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What's the update on this amp? Everything wired in? What's the noise level at idle?
Any closer to having a sound clip?
With respect, Tubenit
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It's sitting there waiting for me to get back to it.....after the hurricane, my company was inundated with flooded welding machines, which present a huge problem for us, because theorhetically, once a unit is submerged in water, it "shouldn't" be used again, due to corrosion and insulation breakdown.....BUT, it's our job to dry some of them out, and try to get people back to work... so it's been some long days.
The amp is nowhere near "done"...now that I've gotten this far, I have to read more to learn what I'm actually doing....I realize, by listening to guys on this forum, that there is A LOT more to learn.....I haven't stopped thinking about it for one day, and have changed my mind about 10 times as far as what my next move will be... I am completely addicted to building and have to fight the urge to build everything I see and hear...
I have downloaded all of the material from Sluckey's website and am reviewing all of it to try to broaden my horizons...
Here's what I'm thinking today about the amp on my bench:
- I was in re-introduced to a guy who wants to sit in with me to try to find an amp design for him....I really want to build a "holy grail" amp,,,and while searching through schematics, I saw that the AA864 Bassman has a VERY similar design to this Twreck,,,so I am considering converting this to a single channel (normal) version of that amp to get him taken care of....it shares a lot in common with the AB763 LITE that Sluckey has on his website,,,,so I'm thinking it would be an easy road, and a lot of the guesswork has been taken out of it for me.
My intention is to "roll back" this amp, in sections, so he'll be able to hear the differences, and decide for himself if he wants to go all the way back to the AA864, or if there's something in the wreck design for him. I invited him to sit with me for the day and make the changes, and play through each stage, to see where he would want to stop.......I'm thinking about putting the Bassman preamp circuit on another temp. board so that at some point we'll just be able to jump all the way over to that sound by just wiring it in. (not sure if that's easier than making all the component value changes on this board)
If he decides he wants to do it I'll probably go for it, in hopes that it will enlighten me about the differences in designs/sounds....I will try to get a clip recorded before I make the changes.
AND, in the meantime, my curiosity about doing a Dumb OD type amp has grown,,,,a TOS,,,a 5 watt,,,a Stout,,,a pentode preamp........
AND, I still have to keep my wife happy!.....she hurt her back so I've been taking the brunt of the housework.
Thanks for asking and caring and helping me through all of this....I'll be back to writing updates SOON
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SG,
Just gone through this fascinating thread, very informative indeed. The way you are tweaking the design, part values is admirable and I think well suited for a tube breadboard like Tubelab's: http://www.tubelab.com/The_Tubelab.htm (http://www.tubelab.com/The_Tubelab.htm). Looking forward to read more about your experiments.
Jaz
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a guy over at the amp Garage asked about paralleling V2 in a 'wreck.I think with some tweaks to the bypass caps on V1 and the gain control,a fat sounding V2 might be really cool sounding.
I'm definitely putting it on the list for my next experiment.
We have way to much here on the Hoffman forum,don't we? :happy1:
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I tried paralleling V2a into V2b, with no real noticeable results (for me),,,,but I was looking for waaay more gain......cascading V2a into V2b really lit this amp up, and I'm so happy jojo thought to tell me to try it.......great way to make use of that unused triode :thumbsup:
JoJo and Tubenit each get 33% on this build......all I did was throw parts at it :l2: (but thats worth 34%)
Thanks jazbo,,,,that's very interesting :huh: ....at one point during my build my amp kinda looked like that
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I'm going to get an amp up and running in the next week or so and try out some of those mods.
Thanks for sharing your experiences!
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OK...the holidays are over, so it's back on
Most of the changes I made in the past week were a result of comparing my schematic to others,,,and reading, including some of Merlin's book
The amp definitely sounds better now than it did before this round of tweaking,,,so I feel really good about all of the changes made
I figured I would start with an updated current schematic, and a few explanations:
(items in RED are adjusted since last schematic)
-Added 500p shunt cap on V1 socket from input grid stopper to ground to try to help with "fret squeal" ("seemed" to help)
-Returned treble cap back to stock 500p value, and definitely heard a big difference (brought back highs, and the enhanced harmonics really opened the entire sound back up)
-Increased grid stopper value to150K and added a paralleled 500p cap to the grid V1b (2nd stage)
-Increased cathode resistor on 12AU7 triode to 3.9K
-Added a 68K grid stopper to V2a (third stage)
-Eliminated boost limiting resistor on V2a (really brought in some serious OD,,,,so I dialed the the preceeding grid leak (temp pot) down to 250K, and WOW,,,nice give and take moment there.........went from lots 'o mud to scorching / defined lead tone
-Played around with resistor values in the PI and wound up with what sounds to me as the best combination
-Lowered the value of PI coupling cap down to .022 at first (that was too far for my taste), and settled on .047 (nice and punchy, without being too "squalky"
-Removed the 2- 51K resistors that I had originally put into the wipers of the dual PPIMV pot, because I think the amp sounds better at a lower setting on the PPIMV witout them (didn't know why they were there in the first place,,,on the schematic from jojo)
This amp is a serious ONE CHANNEL lead monster, and I feel like I am very close to the sound I had set out to find when I began tweaking!
I can't thank the guys on here enough for the confidence to do what I did!
There are a few things left to do including adding a lead boost switch which will interrupt the 3rd stage 1uf bypass cap when disengaged
AND, re-drawing the layout to fit all of the added components which are still hovering above the board.
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I was back at it again last night, and it's cool to not have to rush through this process....
I have thought that the amp sounds great, but I have the same illness as most of you, and great just isn't great enough :icon_biggrin:
I was unhappy with the idea of a shared tube for V1 because I don't want to have to be stuck with a 12DW7 in order to get my AX7 + AU7 as V1a and V1b.......so I took out the drill and added another preamp tube socket so that I could have a separate 12AX7 tube as my first stage.
I also chose to parallel the triodes in that new tube and put a high quality TAD tube in that spot,,,,, and followed some of my readings to split the plate load and cathode resistor values in half,,,,,with the intention of getting more gain, and lower noise in that input stage........
I also thought it would be a good idea to lower the impedance feeding the tone stack.....
The result was a much improved defined clarity, that had slowly disappeared during some of the other mods that I've done.....
And the coolest part for me was that it increased the "sustained harmonic feedback" effect that I've tried to preserve throughout this process....I can now get it at a much lower setting on the volume knob of my guitar (it will hold for as long as I can hold it :thumbsup:
So, of course, I had to take it too far, and because I now have an unused 12AU7 triode in V2, I decided to parallel those 2 trodes as well,,,and the result was an incredibly puncy gain,,,but just too over the top for me,,,so I disconnected the paralled jumper wires for that tube, and it was better that way for me...
This amp wants to punch you in the face and take your lunch money :l2:
Here's how I left the amp sitting for now :laugh:.......all new adjustments are in BLUE
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Are you leaving the 12DW7 in V2's socket or did you use a regular 12au7 when you paralleled them??? Did you try any other tubes in the socket when wired that way also???
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Are you leaving the 12DW7 in V2's socket or did you use a regular 12au7 when you paralleled them??? Did you try any other tubes in the socket when wired that way also???
I got rid of the DW7 and put in a new JJ AU7,,,didn't have time to try anything else, but did play it a awhile as-is, and it's getting closer...
I had one of those moments where it sounds almost perfect,,,and then you add something,,,and it's a mistake,,,so you have to back up and find what you just had :laugh:....(when I paralled the AU7 triodes, it took away some of the harmonic feedback thing and introduced some high pitched bad feedback, and just made it way to front end heavy)
I'm not done, but I'm also not sure what my next step will be,,,,,,maybe something to tame the 3rd stage a bit ?
I'm sure I'm gonna mess with the plate and cathode resistors on that input AX7, maybe reduce the gain a little ?
And go back and take a closer look at the grid stopper feeding that AU7 ? ( I think I settled quick there)
I'd also like to try and smooth out the highs in general,,,they are a little brutal and sharp :dontknow:
BUT, so far, I haven't felt like turning back around and I really like where it's heading :thumbsup:
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I'd also like to try and smooth out the highs in general,,,they are a little brutal and sharp
I'd try the "enhance" cap (again) on the entrance plate resistor to the LTPI. Maybe 82p - 120p? All the enhance cap did on my amps is increase harmonics and blooming. No negative impact if the value was right. I could not even tell any loss of highs ........ just smoother to my ears.
And then maybe some of the smoothing caps like are using on the D-style amps from plate to cathode. Maybe try 150p - 390p. If you have a 220p, maybe start with that.
Remember these can just be clipped in for the experiment.
With respect, Tubenit
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Gotcha :thumbsup:,,,thanks again T and very sorry to make you repeat yourself... :embarrassed:
Earlier in this process I definitely leaned more towards changes that had a greater immediate impact :icon_biggrin: , and glossed over some of your suggestions for smoothing because I couldn't hear a huge difference by implementing them.......
Now I feel like I'm at a point where I've actually caught up to where you wanted me to be, (through trial and error) and I'll have to listen harder to fine tune the end result....
Every time I get close to settling,,,,I read something else that brings me back, and reminds me how much fun this can be...
I'm gonna double back over the thread and try some things I may have missed, and report back soon.......
I realize that I still owe you guys a soundclip,,,,,and that you really can't help me fix my sound, if you can't hear it :wink:
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Some may not like this but another "option" is to go the "good Dr." route and try clipping in a conjunctive filter? His famous little Camen Ghia & possibly others (don't know about all?) uses this to tame and linear-ize his otherwise bright & harsh designs. The technique is you leave it bright & harsh on purpose without any sort of smoothing caps keeping all the naturally occuring gain and sharpness and let this (conj. filter) even & smooth things out... many many people like the end result of his amps as you know. I'll keep it short for now on this subject.
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Thanks Jojo, I found some good reading here: http://www.el34world.com/Forum/index.php?topic=7620.0 (http://www.el34world.com/Forum/index.php?topic=7620.0)
I'm gonna go back through all coupling cap values, while I'm trying T's smoothing cap suggestion...
Love the new avatar, by the way :thumbsup: :huh: :grin:
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That's a fine way to go however it can & usually takes days going through the gammut of various possiblities and combinations to find your happy place. The conj. filter is quicker before you go the other route is all. I should re-read some of this when I have more time, I'm a little lost with where you're trying to go but I thought you were on just the bright side or is it brittle or rhaspy or gritty?
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That's a fine way to go however it can & usually takes days going through the gammut of various possiblities and combinations to find your happy place. The conj. filter is quicker before you go the other route is all. I should re-read some of this when I have more time, I'm a little lost with where you're trying to go but I thought you were on just the bright side or is it brittle or rhaspy or gritty?
It's definitely a juggling exercise... :laugh:
The highs effect the lows, and I love the lows to jump out and punch you, but with that has come some bright, gritty, brittle top end
I was hoping to smooth the highs, without losing them,,,if that makes sense....
I had time to try a smoothing cap, from plate to cathode on the third stage, and I started with 250p (heard a slight difference for the better)
jumped up to 500p (still only a slight difference, to my ears),,,so like i do,,,I took it to the extreme, and put in a .002uf (so I could really hear a difference,,and I did).....ran out of time,,,but there's lots of room to work there + trying it on other stages....
I'll definitely try the conjunctive filter,,,BUT, why did you word it as "some may not like this" ?
I'm also not worried about finishing any time soon....it's more fun for me to go down this path slowly, and make sure I touch all of the bases....when I get to the end I want to know that I didn't settle because I ran out of time.......it's great to not be in buisness, because I'm the only customer I need to impress :icon_biggrin:
ALSO, there's one other thing that I want to clear up (the way I worded something).....My true intention for paralleling the first stage was to lower the impedance feeding the tone stack.....I knew the increase in gain would be a by-product,,,and i'm going to go back and lower that, because it "feels" like i'm hitting the front end too hard again (but I do like the clarity that came back by paralleling those triodes)
I had to separate those first 2 stages and get rid of the 12DW7, because I wanted more options in tube selection, and didn't want to be chained to a "specialty" tube.
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As a result of joining in on another thread about a balance control in a Hiwatt http://www.el34world.com/Forum/index.php?topic=15080.0 (http://www.el34world.com/Forum/index.php?topic=15080.0)
I decided to try to implement this mod in my circuit....
At first glance it appeared pretty simple, so I dove right in,,,and i'm sure glad that I had recently added that tube socket, because it would have had to have been done to accomplish what I was trying...
To this point this has been a single channel high OD build, and I have been trying to figure out where or how I was going to implement a "solo boost".....or actually just a way to get less drive for rhythms, and then switch to full "Turbo" for leads.......
So this mod appealed to me for a couple reasons:
-I wanted to see how the amp would change if I changed the location of the tonestack
-I wanted to see if it would give me better control over the front end gain i've been back and forth about
-I wanted to leave no stone unturned in my quest for super-cool circuit nirvana
I didn't have much time to stay and play, but just figure I should update the schematic, because it has brought about some big changes
I was most surprised by the fact that it really didn't change the sound of the amp all that much, but did give me a better control over how much gain was coming off the front end....I like the idea and will continue to experiment in the coming week......
the input volume and balance controls appear to work fine, but the switch has no effect, and i'm working to resolve whether I may have miswired it :sad:
Any help would be greatly appreciated.. :thumbsup:
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http://www.tubesandmore.com/products/K-SNUB2 (http://www.tubesandmore.com/products/K-SNUB2)
Here's a link to conjunctive filter kits at AES.
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CG, I only see that it appears the two pots are wired in reverse, everything else appears fine. It still should work. The stack being placed or used differently should definitely make a change & difference.
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Thanks for looking jojo....
I'll take the microscope to the whole operation on Mon......I don't think I miswired anything,,,,but you just never know :wink:
It sounded a little different with the tonstack moved, but not as much as I expected...
The basic"character" of the amp is still there, and I'm thrilled with that!
I've made so many changes to the original board,,,that some stuff is just more difficult to trace out than it has to be,,,,so i'll go at it with a fresh set of eyes :huh:
This was a BIG jump, and i'm glad I did it because it brings a whole new level of "creativity" into play.....
Just for the record....I had tried some smoothing caps and an enhance cap before the mod, but never settled on anything,,,so i'll go back in once I get this working and tweak away..........I'm having fun with it and learning as I go :grin:
EDIT: Found the problem.....1K resistor coming off ground switch, where it should've been 1M :rolleyes:
Edited pic to reflect corrected pot wiring as well...thanks jojo!!
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The schem looks fine, I was talking about the layout drawing (see attachment) is all. If there's a lot of stages in the preamp then you'll not see/feel/hear as much difference w/ the placement as you would w/ only a few stages...seems "normal" to notice this.
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Well,,, I got a little frustrated last week with swapping components,,,and how sloppy my board has gotten,,,,so I decided to lace up a "prototyping board" for the cathode leads that I wired in on Saturday..
I mounted a small section of board to the top side of my chassis, with some of the turrets laced together to give me access to each component in it's own individual path....(initially created a wicked ground loop, but figured it out quick and got on with it)
I ran all 4 stages cathode wires to the separated paths and also used small trim pots for the last 2 stages to try to "dial in" the correct level of gain at each stage.....(if I had more trim pots, I would have used them for all 4 stages)
My intent is to use this board as a "prototyping" board during the "design" stage, before making a final board layout,,,,and then being able to remove this and take it to my next project,,,,(at which time I will put trim pots in all 4 locations)
I also removed the "balance mod", in an attempt to simplify and focus on getting the base sound zero'd in...
I went back and put the paralled connections back on V1 (because that just sounds the best to me) and wound up with a 68K plate and 680R cathode resistor values (taken from some things I had read about an input stage on a popular boutique amp,,,thanks again Jojo)....basically-reduced values help to lower the noise floor in that 1st stage
I took the 12AU7 out of V2, and put back a AX7 with a 150K plate and 3.9K cath. with 2.2uf bypass cap (now 1 unused triode,,,,hmmmm?)
I also completely removed the tonestack which obviously helped "push" the signal along!
I was able to dial in a great combination of values at all stages, and now feel closer than ever to having this amp completed :thumbsup:
I changed the value of the 3rd stage cath. resistor to 3.9K (from 10K), and raised the 4th stage value from 33K to 47K
I removed the bypass cap from the 3rd stage, which was a HUGE source of noise,,,and still have more than enough overall OD to keep me happy :icon_biggrin:
I've also continued to experiment with plate resistor values on the output tubes (with 470R providing a more open sound to my ears, compared to stock 1K), and conjuntive filter values (with no filter still being my favorite) (I'm not done)
I'll stop back and post the schematic when I get it drawn up.....to my ears, this is the most professional sounding setup I've tried so far, with much less noise, and a much purer sounding tone----less buzzsaw :l2:
The main thing I have continued to focus on is the effect of ultimate sustain that blooms into harmonic feedback, and have done everything in my power to enhance that during this process.....if something takes away from that quality---it gets removed,,,and if something enhances it, it gets pushed to the highest possible degree to see how far I can take it, without creating excessive noise................that is one big 'ole tug-o-war!
**EDITED- added pic of head cabinet I built with my new dovetail capabilities :grin:
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Nice work SG, I think you have well and truely hit the nail on the head when it comes to tweaking these amps. I get really lost when you finish a build and it persents a problem i find it a nightmare to fix, so to get the base amp up and running THEN start adding the extra's.
I'm about half way through building the JP Hiwatt (with 6V6s) and NO extra's (fx loop,reverb, ppimv......) but i am keen to see what the "balance" does. Thanks
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"so I decided to lace up a 'prototyping board'"
easier, safer, & more organized :thumbsup:
"(now 1 unused triode,,,,hmmmm?)"
:think1: don't let it bug you at this point
"removed the bypass cap from the 3rd stage, which was a HUGE source of noise"
yes, further down the line can be problematic (& parasitic/oscillation trouble)
"plate resistor values on the output tubes (with 470R providing a more open sound to my ears, compared to stock 1K), "
??? are you sure you're not talking about the PI tail resistor(s)? The lower value gives more drive w/ a bit more clean response in the PA, (which I like)
*are we ever going to hear this thing? :laugh: (it could be helpful in helping w/ suggestions or opinions, and so we could follow what you're describing)
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Thanks TIMBO,,I did like the balance and may go back to it,,just wanted to keep the signal pure at this point
"plate resistor values on the output tubes (with 470R providing a more open sound to my ears, compared to stock 1K), "
??? are you sure you're not talking about the PI tail resistor(s)?
OH----I MEANT SCREEN RESISTORS ON EL34s......I thought I would like the more compressed sound of raising the value,,,BUT I actually liked it the other way and wound up dropping the value to 470R from 1K......re-biased and liked it
Sorry about that,,,sometimes I trip over all of this "new" terminology :embarrassed:
*are we ever going to hear this thing? :laugh:
YES, it was just way too crazy noisy before now and was a little embarrassing (I was ignoring the noise to get to the end result)
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OK,
So in an attempt to be a man of my word, I have included a link to a quick sound clip sample of this amp in it's current state...
http://www.soundclick.com/player/single_player.cfm?songid=12375190&q=hi&newref=1 (http://www.soundclick.com/player/single_player.cfm?songid=12375190&q=hi&newref=1)
It's a terrible recording, and it contains the scratchy noise that I have not been able to get rid of in my crappy little recording setup....I obviously didn't bother tuning the Warmoth Partsocaster, played through the JB bridge pickup, straight in, and out through a Celestion G12H-30
I don't think the amp sounds this bad in person,,,,,but I also don't believe that I look as old in person as I do in pictures :icon_biggrin:
Actually I'm sure it doesn't sound this bad in person,,,and has a much more open quality than this clip would dictate....this clip makes the amp sound like there is a cardboard box over it :embarrassed:
I only promised that I would post a clip,,,,not a good one :wink:
So this hereby fulfills my commitment to post a clip before moving on to another project,,,,and I will be temporarily answering another calling, by going in the complete opposite direction in search of a great clean sound.
Here is the updated preamp schematic, as the amp sits,,,not complete, but there is a lot left to do and try and I will be back shortly
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You covered Neal and Jimmy. Sounds good, but had to turn up the speakers. Nice sounding amp. :worthy1:
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I only promised that I would post a clip
Nice clip! Very positively impressed with that & I liked it. It had some pretty cool harmonics in the tone and true ROCK OUT tone to it. Had a huge tone to it.
THANKS for sharing it and your innovative approach!
:thumbsup: :thumbsup:
With respect, Tubenit
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Thanks guys...
It is a little nerve-wracking when you press record,,,and you wind up with that
I had a hard time getting past the crackling, and am still not sure what was/is causing it (it's not coming out of the amp)
But it's an OK example of the gain and power of this amp, and hopefully can give someone an idea of what this might sound like if you build it...
I'll work on my recording technique (and playing technique---it's amazing how fast you get rusty :embarrassed:),,,and try to come up with some clips that actually sound like they weren't recorded by a 5 year old............eventually :icon_biggrin:
Sounds good, but had to turn up the speakers.
Yeah me too....something happened when I converted it to MP3 :dontknow:
I'll stick to building amps and leave the recording up to the pros!
Thanks again for the kind words :thumbsup:
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Nice work SG :icon_biggrin:
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Thanks Timbo .... :occasion14:
I started thinking about the sound here and realized that I forgot that the amp still has no tone stack
So if it sounds a little thick,,,that's partially why :grin:
The more I listen to that clip, the more I want to re-do it ......I'd like to capture the way the amp actually sounds when your sitting next it,,,,,but I just don't have that resource
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OK, here is a SCH editable schematic and layout for your amp.
Download ExpressSCH and then you can just click on a component and change component value. It is a VERY intuitive easy to use program. I can't begin to tell you how useful drawing schematics has been to me in understanding amp topology and design.
On the layout board, ........ obviously we can edit this and move things around. I left room on the far right of the layout board to add a tone stack IF you want to. We can also move the V1-3/8 cathode components to the far right side of the board. We can also move the presence pot to the far end on the left as is normally done.
I wasn't sure what all you had after the LTPI, so I referenced a previous schematic that you posted that showed a PPIMV. I have never drawn up a PPIMV with fixed bias before.
I renamed your amp the "SiG 001" but change that to whatever you want.
Looking forward to whatever you finally come up with.
With respect, Tubenit
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SilverGun,
I don't know if you have already tried a 5E3 tone stack with your amp or not? It would be a very easy experiment to try out. The 5E3 tone stack has very low insertion loss. You could also lower the 330k to 220k into the next gain stage grid to compensate.
Just an idea, ........... not pushing any agendas.
with respect, Tubenit
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I don't know if you have already tried a 5E3 tone stack with your amp or not? It would be a very easy experiment to try out. The 5E3 tone stack has very low insertion loss.
No I had not,,,,,,but I like the looks of it
Thanks so much for all of your work, and I hope this amp will be good for someone else somewhere....
As soon as I get back to it, I'll continue to update the sch file, and hopefully post some better recordings....I also want to add a d'lator and mess with effects,,,so IT AINT OVER :icon_biggrin:
Nice work T :thumbsup:
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...and eight months later, let there be SOUND!!! But what is it? It appears to be some kind of time warp from back in the day coming from my parents' old Marantz stereo system that used to play those big black vinyl records? The music seems to be from that era too?! Holy retro Batman! SG no wonder it took you so long, you didn't have to recreate an actual LP record recording for us. A simple mp3 would've been fine and much easier, but many thanks! That was priceless and definitely worth the wait!
Okay, all kidding aside (which you deserve btw) - the amp sounds very good and what I had in mind (less the snap crackle and pops). But I think some time ago I began to anticipate more of the what and how you would play rather than actually how the amp would sound after "the great build-up". And I must say the Zep was a bit of surprise but definitely not the Journey - which at this moment is very ironic as it really has been quite the journey eh???!!! ;)
Okay really not kidding now - in your schemo the way it's drawn, it appears you don't have any voltage dividers? And after all of those stages too! Is this actually correct? It's hard to imagine the signal level isn't too high causing you any issues? Your sustain seemed to be possibly dropping off a bit short but it was hard to tell to be sure as you didn't keep it more than a couple seconds a couple times. Check out your ecstacy that you like & a badcat as examples.
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...and eight months later, let there be SOUND!!! But what is it? It appears to be some kind of time warp from back in the day coming from my parents' old Marantz stereo system that used to play those big black vinyl records? The music seems to be from that era too?! Holy retro Batman! SG no wonder it took you so long, you didn't have to recreate an actual LP record recording for us. A simple mp3 would've been fine and much easier, but many thanks! That was priceless and definitely worth the wait!
Okay, all kidding aside (which you deserve btw) - the amp sounds very good and what I had in mind (less the snap crackle and pops). But I think some time ago I began to anticipate more of the what and how you would play rather than actually how the amp would sound after "the great build-up". And I must say the Zep was a bit of surprise but definitely not the Journey - which at this moment is very ironic as it really has been quite the journey eh???!!! ;)
:l2:....I knew that was coming,,,and you're right I DESERVE IT........all that buildup ,for THAT (3 chords on an out of tune guitar :icon_biggrin: )
I like to think that I'm a fairly technically inclined person,,,,,but I can't believe how these recordings come out......I bought a new mic, cable, but there has to be something going on in the input on this Tascam, and I'm too busy with life to figure it out........
Worst thing that happened was I sat with everything rigged up for 1/2 hour and just played and thought "there's some good stuff there,,,I'l just edit it down"....so I packed it up,,,took it home only to find out---I NEVER PRESSED RECORD :BangHead:....
So that was it,,, I took an older clip and threw it up, cause I didn't want to face the wrath of the mojo gods as I start a new project :icon_biggrin:
I hate all of these youtub vids where you can hear the guy picking the strings over the actualy sound of the guitar,,,,,so I want to record at full volume through a real mic.......BUT :huh:
I'll get back to it.....it was kinda cool to post it,,,but also embarrassing..........I'm sure HBP is gonna expect a little better quality from me
For the record---Zep is my No.1---always has been
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...and eight months later, let there be SOUND!!! But what is it? It appears to be some kind of time warp from back in the day coming from my parents' old Marantz stereo system that used to play those big black vinyl records?
This is offensive. First it is the avatar and then you make fun of my vinyl collection. I'll tell you the best possible music comes from old black vinyl. Not really, I have an old Reel to Reel which is way cool. You young lads just do not appreciate the experience of listening to music with your multi-tasking. Take a break, get a turntable, a tube stereo and read some liner notes and look at the great artwork of the cover.
However, the 28 gig drive in my truck full of mp3's is very cool I must say! :l2:
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Okay really not kidding now - in your schemo the way it's drawn, it appears you don't have any voltage dividers? And after all of those stages too! Is this actually correct? It's hard to imagine the signal level isn't too high causing you any issues? Your sustain seemed to be possibly dropping off a bit short but it was hard to tell to be sure as you didn't keep it more than a couple seconds a couple times. Check out your ecstacy that you like & a badcat as examples.
I'm sure you can tell I take a pretty dumbed down approach to his stuff :wink:.....all I did was duplicate the 2nd -3rd stage from the original T-wreck schemo that I had started with,,,so I'm only going off of my ears....and I want it to be a little different
Biggest issue: The gain control has a very limited "gain" effect, but adds more of a "gain-tone" effect with the cap on the wiper (I don't mind)
The sustain is really good, and the one thing that I wish I would have displayed in the clip was the sustain into feedback that it does very well.
The one thing that I did wrong during this process was get distracted....I started thinking about the effects too soon, and had a lot to learn....(obviously, from our phone conversation----and I don't want to be a pain in the A##)
Also, the breadboard, took longer than I would've liked......but now that it's almost up and running, it's a joy to work with,,,,worth every minute
So, excuses, excuses, excuses :icon_biggrin:
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Two questions-
Are you still thinking of using the EQ circuit you posted in the High Gain Preamp section, in this amp design?
Where did you find the IC's used in the Parametric EQ?
I like the sound of your amp. It has a very rich harmonic content.
Fox.
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Are you still thinking of using the EQ circuit you posted in the High Gain Preamp section, in this amp design?
Absolutely......I have to wire up the D'lator first and then I'll be trying this and a delay
Where did you find the IC's used in the Parametric EQ?
http://www.newark.com/jsp/search/productdetail.jsp?SKU=60K6989 (http://www.newark.com/jsp/search/productdetail.jsp?SKU=60K6989)
http://www.newark.com/jsp/search/productdetail.jsp?SKU=60K6986 (http://www.newark.com/jsp/search/productdetail.jsp?SKU=60K6986)
Thanks SF...I don't think the clip does the amp justice, but I appreciate the compliment
If you're anywhere near Philly, stop by and try it out :icon_biggrin:
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SG, if you were to put the gain control down the line more you'd get a better response out of it. Also controlling the signal gain would be of benefit in this regard too. But, alas you'd have to rewire some things...are you "experimented out" w/ this thing?
Ed my man your memory is excellent! ;) I actually have a pretty "groovy" record collection also. :l2:
It's not very convienient having to turn the darn things over after only 4 or 5 songs & 25 or so minutes. .mp3s with shuffle play have spoiled us now. It's pretty interesting I have things from Woodstock, Hendrix, & Black Sabbath to about the 4th or 5th Van Halen record to even NewWave & PunkRock stuff or Dire Straigthts, ZZ Top, Bon Jovi, & G & R, U2 & Journey stuff before things went all digital. The album art was some of the best stuff about the records too. Back in the days, there was very little information or even pictures of the bands and what they were up to. Way unlike today's info machine and sites like TMZ & others always looking for dirt on anyone with a name.
One of my all time favorite album covers was the inside of Tres Hombres. I always got the munchies staring at it and it set the picture in my mind as the ultimate Mexican meal grind. While getting the munchies we would get fired up blasting the record while watching an old western or cowboy & indian movie with the sound off. It was a riot and uncanny how the music and words could sinc up with each other or maybe it was just my low tolerance level back then? :laugh:
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One of my all time favorite album covers was the inside of Tres Hombres. I always got the munchies staring at it and it set the picture in my mind as the ultimate Mexican meal grind. While getting the munchies we would get fired up blasting the record while watching an old western or cowboy & indian movie with the sound off. It was a riot and uncanny how the music and words could sinc up with each other or maybe it was just my low tolerance level back then? :laugh:
[/quote]
Did Jesus ever make it to New Orleans, that's is what I want to know.
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Did Jesus ever make it to New Orleans, that's is what I want to know.
He did actually when he reached Shreveport and saw this skinny little blonde boy named Kenny and blessed & annointed him as the next deciple to follow the greats Jimi & Stevie.