My new amp...let's wreck it

[SILVERGUN]

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

[SILVERGUN]

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

[stratele52]

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/). 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

[tubenit]

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

[stratele52]

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/). 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

[jojokeo]

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?

[SILVERGUN]

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

[SILVERGUN]

What kind of MV did you install, I can't seem to find it on anything posted?

[SILVERGUN]

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

[cbass]

Search for Larmar master volume you should be able to find a diagram

[jojokeo]

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! ;)

[SILVERGUN]

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
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

[jojokeo]

  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)

[SILVERGUN]

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"
  I might be losing my ears, because of back to back nights tweaking.....

Is .0047 too high a value for that spot?

[SILVERGUN]

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??

[tubenit]

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

[SILVERGUN]

Had to walk away for tonight....need new ears
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.)

[SILVERGUN]

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? 

[jojokeo]

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.  

[SILVERGUN]

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

[SILVERGUN]

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!

[William_G]

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

[jojokeo]

This is the ppimv for fixed bias type of master volume control you want to use when/if you get around to it.

[SILVERGUN]

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

[SILVERGUN]

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!

[SILVERGUN]

Here's the current schematic.....for anyone who is keeping score:

[jojokeo]

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.

[SILVERGUN]

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

[tubenit]

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

[alerich]

-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.

[SILVERGUN]

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 ...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?"

[tubenit]

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

[SILVERGUN]

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
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!

[SILVERGUN]

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 

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

[jojokeo]

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. 

[cbass]

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

[SILVERGUN]

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!

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!

[SILVERGUN]

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..

[SILVERGUN]

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

[cbass]

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

[SILVERGUN]

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 

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

[cbass]

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

If you care to share,,,go here and give us the story behind cbass:
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

[jojokeo]

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.

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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.

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.

[cbass]

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,, ,,, 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