Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: SILVERGUN on April 15, 2014, 09:00:42 pm
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After seeing Sluckey's recent work on the AC15, I felt the need to post something to show him how his work inspires others.
It's pouring rain here, and I couldn't care less......and that's what made me think of the AC15 thread.
I'm sooooo far off the reservation on this one that I'm just going to give you a glimpse into the future,,,,and then wait to make sure it works before I post the rest. :l2:
I promised myself that I was never gonna try to squeeze 100 lbs. of crap in a 20 lb. box,,,and yet, here I am.
Yes, that's the PT in the base of a 2x12 cabinet :think1:.... I am tempting the amp gods... :icon_biggrin:
Cross your fingers for me.
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Supply on one side - tubes and tonestack on the other? I take it the controls are on the top where the cutout is? That seems like a lot of signal wire routing? Lots of grunt, tiny living space! Cool! I like the Al angle for the supply and on/off switch - been there!
Jim
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Where is the corncob gonna go!?!? You can always use it as a carry handle! :l2:
Jim
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Supply on one side - tubes and tonestack on the other? I take it the controls are on the top where the cutout is? That seems like a lot of signal wire routing? Lots of grunt, tiny living space! Cool! I like the Al angle for the supply and on/off switch - been there!
Yeah, just separated the power supply from the chassis.....the tubes, board and controls will all go in chassis like usual....controls in cutout
Where is the corncob gonna go!?!?
I put it where you suggested and I haven't been able to sit all week. :angry:
:l2:
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Do I have to worry about grounding my choke to the chassis?
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Do I have to worry about grounding my choke to the chassis?
no
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Will the speaker fit?
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Will the speaker fit?
Yeah, it's tight but clears by about a half inch.....front mount
Good lookin' out!
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I found these small, cheap 1kv- 35 amp power entry plugs that I'll use to get the B+ and bias voltage into the chassis safely:
http://www.newark.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=15003&langId=-1&urlRequestType=Base&partNumber=25R4664&storeId=10194 (http://www.newark.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=15003&langId=-1&urlRequestType=Base&partNumber=25R4664&storeId=10194)
http://www.newark.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=15003&langId=-1&urlRequestType=Base&partNumber=25R4668&storeId=10194 (http://www.newark.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=15003&langId=-1&urlRequestType=Base&partNumber=25R4668&storeId=10194)
For the record....
I'm gonna do male by female for one connection and female by male for the other connection so that they won't be able to get plugged in the wrong way...
In other words, have a female connector on the chassis to attach B+ to and then a male conector on the chassis to attach the bias V in
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Now Thats Mad Science with a bit of Voodoo thrown in for flare!
:worthy1:
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Now Thats Mad Science with a bit of Voodoo thrown in for flare!
OK,,,,maybe not all that, but it's good to see you lurking here llama :undecided:
For all of you amp porn aficionados out there, this thread will be the equivalent of the slow striptease...
Partially because I am slow,, but mostly because I usually do a horrible job of documenting what I do,,,and I'm trying to change that.
So, sorry for the lame pics, but I assume it's better than no pics.
I added the rivets on the corners because one of the spot welds popped on me....I don't like using this thinner .04 aluminum, but it was the only thickness I saw available in this 17" x 4" x 3" chassis.
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The first three amps I built this millennium used that same chassis. One of them broke and I pop riveted to fix it. They are OK if you don't put any iron on them. You can literally twist them like a pretzel with just your hands!
Oh, and it's very tight working inside. You really gotta plan ahead and layer your stuff as you build. Doug's 3.125" wide boards do not work well. I ripped my boards to 2.5" to give room for input jacks. If that chassis had only been 5" wide it would have been soooo much easier to work with.
Here's a link to a couple pics of my 3x4x17 Hammond projects...
http://home.comcast.net/~seluckey/amps/5e3/sisters_rear.jpg (http://home.comcast.net/~seluckey/amps/5e3/sisters_rear.jpg)
http://home.comcast.net/~seluckey/amps/18w/18w_03.jpg (http://home.comcast.net/~seluckey/amps/18w/18w_03.jpg)
Not trying to dis your project at all. But I wanted to share my thoughts about that chassis.
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The first three amps I built this millennium used that same chassis. One of them broke and I pop riveted to fix it. They are OK if you don't put any iron on them. You can literally twist them like a pretzel with just your hands!
Yeah, I noticed that,,,and that's how I popped the one spot weld,,,just by twisting it a little to straighten it..
And, that's why I decided to separate the power supply,,,cause it's a pretty big PT, and there was NO WAY that chassis would hold it up for a second.
Oh, and it's very tight working inside. You really gotta plan ahead and layer your stuff as you build. Doug's 3.125" wide boards do not work well. I ripped my boards to 2.5" to give room for input jacks. If that chassis had only been 5" wide it would have been soooo much easier to work with.
Yup, I'm with ya...I've spent about 10 hours sitting around drawing layouts,,,and now you've got me re-thinking it again, 'cause I was gonna use a 3 1/8" wide board.....
I like pre-assembling, so I'll do whatever I can outside of the chassis first.......It's gonna be tight, but at least I eliminated a bunch of power supply wiring.
Wish me luck!
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To build the amp with a splitted chassis isn't a bad idea
Sluckey and HotBluePlates buided amps in that way, not exactly as you want to do, but similar
http://home.comcast.net/~seluckey/amps/vox/vox.htm (http://home.comcast.net/~seluckey/amps/vox/vox.htm)
http://el34world.com/Forum/index.php?topic=14263.0 (http://el34world.com/Forum/index.php?topic=14263.0)
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it's a pretty big PT, and there was NO WAY that chassis would hold it up for a second
a simpler solution would be to use a 2 mm thick aluminium sheet to reinforce the top of the chassis
you could put the reinforcement sheet on the external or internal side of the top of the chassis
Ciao
Franco
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I think its a great idea to separate the power supply from the chassis.
Thanks Dr.....let's hope we are right!
a simpler solution would be to use a 2 mm thick aluminium sheet to reinforce the top of the chassis
you could put the reinforcement sheet on the external or internal side of the top of the chassis
Thanks K....that is a good idea, and I will probably have to do that for the OT
:thumbsup:
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That is a fantastic idea, that sucks about your chassis problem
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That is a fantastic idea, that sucks about your chassis problem
Thanks lego,,not really a chassis problem as much as just a chassis heads up for other guys who might be considering using one of these Hammonds.
Sluckey did the right thing by pointing it out, so that others will learn from our misfortune.
I'm kinda glad it made me think outside the box,,,and I just hope that this plan flies....I'm finding that the hardest thing I do is start something that I've never seen done, and then try to plan on the fly. That's why I made the comment on the AC15 thread that I would've stuck to sluckey's original design, because it's always a lot harder to re-invent the wheel.
I was hoping to be further along right now because now I have to watch the Flyers in the playoffs....
Since you're in Manhatten, I'm going to imagine that you are the enemy :angry:
But if you're not a hockey fan, then we're still cool :icon_biggrin:
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BTW HotBluePlates used with satisfaction an XLR connector to pass B+ from one chassis to the other
K
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I was hoping to be further along right now because now I have to watch the Flyers in the playoffs....
Since you're in Manhatten, I'm going to imagine that you are the enemy :angry:
But if you're not a hockey fan, then we're still cool :icon_biggrin:
Mehhhh!!!!!!!! 1st off you might have to go through the Black Hawks! :laugh:
2nd and much more importantly, don't wanna hear about a winter sport after this last winter, :BangHead: :cussing:
It's baseball season!
162 game regular season!
GO CUBS!!!!!!!!!!!!!!!!!
"Red Hots, get your Red Hots here, Peanuts, get your Peanuts here!"
Brad :happy2:
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Baseball - Schmaseball.....(meh!!! is right)
NOTHING even comes close to playoff hockey....get off my thread you lousy "Sweet Home Chicago"ian :angry:
Last time I saw the Blackhawks in the finals, they stole my cup on a weak goal in OT :cussing: :BangHead:
:hijack1:
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BTW HotBluePlates used with satisfaction an XLR connector to pass B+ from one chassis to the other
Thanks AGAIN K, I might have to use that trick for the filaments.....?
I know how much you guys like pictures, so here are a couple more from last night...
Notice the "ash-tray" standby switch :rolleyes:, to be able to keep the power supply all together in that corner...
I didn't like it at first, but it has grown on me, and I'll just say it adds 'character'.
And I mounted the choke right next to it keep it all tight.
I also had to screw in some wood blocks on the inside of the cabinet to fill the space where the chassis wasn't wide enough
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Baseball - Schmaseball.....(meh!!! is right)
NOTHING even comes close to playoff hockey....get off my thread you lousy "Sweet Home Chicago"ian :angry:
:hijack1:
"Play Ball!" :l2: "Beer here, get your cold beer here!"
Brad :m2
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Just a little something to think about... Will you be able to get to those chassis mounting screws once the chassis is full of stuff?
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Just a little something to think about... Will you be able to get to those chassis mounting screws once the chassis is full of stuff?
THANKS again for having a look sir,,, :thumbsup:
I'm hoping they will be ok.
I drilled them a little too quickly, in my haste to get the chassis ready for filament wiring......I like to have all the holes there before I start wiring so I don't get any stray aluminum shavings.
If this was my second one of these, this would be A LOT easier :icon_biggrin:
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I read, but I cannot tell what you are building. You have a PT, but have not mentioned what it is. I see 2 power tube holes, so I know it will not be 400 watts. With only 2 tubes, this is NOT up to your usual mindset Are you getting old or something? For all I know you could be planning 2, 6v6.
I mean I thought 190 watts was low wattage for you. Where are you planing the other 6 KT150's. :w2:
Seriously, it is pretty cool and I do see a few additional preamp tubes and I assume, knowing you, they are not for Tremolo. What sort of high gain monster you planning. I have never seen a high gain split chassis design. Are you sort of making it up as you go along or did I miss your schematic and layout?
Spill the beans baby, inquiring minds want to know.
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Seriously, it is pretty cool and I do see a few additional preamp tubes and I assume, knowing you, they are not for Tremolo. What sort of high gain monster you planning. I have never seen a high gain split chassis design. Are you sort of making it up as you go along or did I miss your schematic and layout?
Spill the beans baby, inquiring minds want to know.
This is that one I mentioned that I'm building for someone else......the schematic only exists in my head and scribbled onto empty pizza boxes.....and the whole project is sponsored by Red Bull :icon_biggrin:
It's coming right off of the breadboard.
- 2 channel... 5E3'ish clean with just input vol., tone, clean vol.
Ultra High Gain channel with 4 gain stages into cathode fol. driven tone stack
- Tubenit'ish fx loop with parallel mod
- 2 - EL34s for 50'ish watts into 2 Celestions..... G12 Century Vintage (for lighter weight on the PT side) and G12K-100
- PT, OT and choke are JCM800'ish
- Nothing fancy!
This player needs a big punch in a small package that will probably take some road abuse, and have to fit in a trunk (hence the shrunken design).....the clean channel will only get used if they accidently fall on the pedal. :icon_biggrin:
I voiced it for lots of tight bass and added a NFB "contour" type control.
I spent approx. 7000 hrs. in the last 2 months, thinking, obsessing, tweaking, playing.....repeat
The very last move was something I picked up by reading a post from HBP, about 2 weeks ago...
I had a little too much sloppy bass and was trying a bunch of stuff, and he had told someone to knock down the value of the coupling caps from the PI to the Output tubes (pretty obvious right?)
Well, that was the magic touch...
In my attempt to have a strong bass presence I had used .1uf,,,BUT found a much tighter sound, feel, response in a lower value of .05, and it shaved just enough to make the speakers happier, without losing the impression of "crushing" bass.
I'll never forget walking out of my shop that night with a big smile, thinking....that's it....I GOT IT! :thumbsup:
Thank you HBP, and everyone else who takes the time to repeat themselves, over and over....sometimes we just need to read it more than once :icon_biggrin:
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Baseball - Schmaseball.....(meh!!! is right)
NOTHING even comes close to playoff hockey....get off my thread you lousy "Sweet Home Chicago"ian :angry:
Last time I saw the Blackhawks in the finals, they stole my cup on a weak goal in OT :cussing: :BangHead:
:hijack1:
SG, Don't worry, the Blues will be spanking the babies and sending them packing in the first round - as a matter of fact, the puck just dropped. We have several of our stud Blues players that have been cheap shot injured (HELLO! League office?!?! HELLO! Anybody home?!?! what a crock...), but don't make this dog mad....
Speaking of spanking...wanna talk about the last Cards/Cubs series? :dontknow: (Sorry Brad, I couldn't hep meself! :icon_biggrin:)
SG, build looking good! Will this have the Herzog? Are you gonna give us a recording of this one when you are done? +1 on the XLR connector. Ritchie used isolation trannies for his Majors when he toured. His tech ditched the power cords and set up connection for power via XLR connectors on amp and trannies (see pic below). Those things can handle some power. The plugs you are using look good too.
Jim
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Yeah I'm a Ranger fan, I'm up in Buffalo now with nephew watching the game. Flyers have always been a tough team, Blackhawks tied right now too, those aluminum chassis can be soldered but the aluminum rods are expensive. The ride from manhattan to buffalo was nice but ling
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SG, build looking good! Will this have the Herzog? Are you gonna give us a recording of this one when you are done? +1 on the XLR connector. Ritchie used isolation trannies for his Majors when he toured. His tech ditched the power cords and set up connection for power via XLR connectors on amp and trannies (see pic below). Those things can handle some power. The plugs you are using look good too.
Thanks man...no Herzog on this one....I gotta get this one done so I can get back to that...
I never would've guessed about the XLR's, but now I'm thinking about them.
And yeah, I'll get a clip of me hacking up some metal riffs when it's time. :guitar1
Yeah I'm a Ranger fan
Alright, I'll look the other way, this time :icon_biggrin:
Tough night for us tonight.....good game, bad score.
Back to the amp on Fri...and the good news is, I've had a layout epiphany :thumbsup:
More good news...preliminary voltage tests were 100% on the money..I can move on!
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Of coarse I missed third period to eat and hang with inlaws and missed it. Glad voltages went well, I got to remember to call about my transformer order tomorrow. Having a goaltender that hasn't been playing is tough.
This is my first scratch amp but looking coward to build a next scratch amp
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Speaking of spanking...wanna talk about the last Cards/Cubs series? :dontknow: (Sorry Brad, I couldn't hep meself! :icon_biggrin:)
Yeah, gonna be a long summer, but still better then that last loooooong winter! :BangHead: :cussing:
Hot Dog, get your Hot dog here! Beer here, get your cold beer here, Play Ball!
Brad :laugh:
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Here's a progress update so you guys don't think I gave up....
Sluckey was dead right about this chassis size being difficult to work in....ehhh
Ed's probably got me on the clock, so I figured I better show some progress before I get demoted back to a Level 1 :icon_biggrin:
I also took a couple minutes and cropped out the crap---painless,,,and I was able to get 4 pics in one post with room to spare
Back on it on Mon. night and I'm getting that,,, getting close feeling :thumbsup:
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GO SG GO :wav: GO SG GO :wav: GO SG GO.......................... SG SG SG SG SG
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I dig it man, where'd you score the turret board? It's a nice color, what are you using for your passives?
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Here's a progress update so you guys don't think I gave up....
Sluckey was dead right about this chassis size being difficult to work in....ehhh
Ed's probably got me on the clock, so I figured I better show some progress before I get demoted back to a Level 1 :icon_biggrin:
I also took a couple minutes and cropped out the crap---painless,,,and I was able to get 4 pics in one post with room to spare
Back on it on Mon. night and I'm getting that,,, getting close feeling :thumbsup:
Nice! No clock here. Good work takes time. I have some projects I have been working on for much longer, but not to say they are good work. Seriously, great concept. Gain to go!
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You got it TIMBO! :occasion14:
I dig it man, where'd you score the turret board? It's a nice color, what are you using for your passives?
Thanks lego, I bought a sheet of this Garolite G10/FR4 and a sheet of the G-11 (green)
I had a bad experience with some prepunched black boards being conductive, so I looked into it a little deeper and found this...I like the black for a "metal" type amp :wink:
http://www.mcmaster.com/#garolite/=rp2os2 (http://www.mcmaster.com/#garolite/=rp2os2)
I use a wet tile saw to rip it down and a steel chop saw to cut to length.
Passives ,,,metal film 1/2 watt resistors and a combination of Orange drop and Mallory 150 caps....nothing fancy
In some spots I like to split the value of capacitance and use a combination of each cap type for "better" tone..
You just missed this thread by a couple months: (still just an unproven theory)
http://el34world.com/Forum/index.php?topic=16281.msg159408#msg159408 (http://el34world.com/Forum/index.php?topic=16281.msg159408#msg159408)
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Nice! No clock here. Good work takes time. I have some projects I have been working on for much longer, but not to say they are good work. Seriously, great concept. Gain to go!
Thanks Boss,
I kinda forgot how time consuming this stuff is.....breadboarding is CHEATING :l2:
Concept is the key word here......we'll see :undecided:
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Nice!!!!!
Brad :icon_biggrin:
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Nice! No clock here. Good work takes time. I have some projects I have been working on for much longer, but not to say they are good work. Seriously, great concept. Gain to go!
Thanks Boss,
I kinda forgot how time consuming this stuff is.....breadboarding is CHEATING :l2:
Concept is the key word here......we'll see :undecided:
:headbang:
Speaking of breadboard….I have been thinking of finally building one of those and I really liked how yours came out so I'll be "borrowing" the design.
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Speaking of breadboard….I have been thinking of finally building one of those and I really liked how yours came out so I'll be "borrowing" the design.
Do it!
Best thing I ever did for myself....
It doesn't have to be the greatest breadboard ever,,,it just has to be.
The creative freedom it has given me is priceless, and I enjoy it so much that I had to make another :icon_biggrin:
I was able to build this amp in 2 nights (coulda been one), tweak it for a month, and THEN start drilling holes....
My variable voltage supply is my favorite part because I built it separately from the 1st board, with a variac + xfmr than can supply 0-480VAC that also has a front panel outlet that can deliver 0-120VAC, so when I'm not using the breadboard, I can still use the variac.
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I actually read that article and had that topic going over at BYOC. some people say it's not worth it and I've read from amp builders it's a great way to do the couplings. It's not much more work at all, my thing is figuring out which ones would be the coupling caps. I'm no amp tech, I'd remember it if some one said it's this cap off of this pin but I couldn't just look at a circuit and know. Could you school me quickly?
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I actually read that article and had that topic going over at BYOC. some people say it's not worth it and I've read from amp builders it's a great way to do the couplings. It's not much more work at all, my thing is figuring out which ones would be the coupling caps. I'm no amp tech, I'd remember it if some one said it's this cap off of this pin but I couldn't just look at a circuit and know. Could you school me quickly?
I'm not really qualified to give technical explanations, but here's my own simple explanation that I use so I can sleep at night...
Coupling caps are used between gain stages to block DC from entering the grid of the next stage.....and at the same time, they are used to shave frequency at a desired point.
The higher the value of capacitance, the lower the frequencies that make it through to the next stage....
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Your input cap would be a coupling caps as well then wouldn't it
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Your input cap would be a coupling caps as well then wouldn't it
Input cap?... :dontknow:
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Shoulda been more descriptive. One article I was looking at about coupling caps. The schematic he had as an example had a cap right after the input jack before the preamp tube and he had it labeled as coupling cap. If you were building say a pedal, you always have the input"tone cap" right after the jack on your build. From looking at schematics of some amps I have laying around none if them had that. It's input jack/resistor then preamp.
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Hey lego, the marshall jubilee has that cap at the input. It keeps DC off your guitar pots, not sure about it being a tone cap. :dontknow:
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Some of the real high gain amps will have whats he,s calling an input cap. I don't know the proper name, could be just that. There is an example in Merlins book a .1 cap to ground at the input on the first tube. Right after the 68k or what ever you use on the first input stage. It cuts high frequencies to curb fret squeel . When you slide your hands down the strings. Ive used it a couple times it also allows me to use smaller caps across the anode resister. Because I have cut some highs at the front end.
Bill
I will find an example and post it later.
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Hey lego, the marshall jubilee has that cap at the input. It keeps DC off your guitar pots, not sure about it being a tone cap. :dontknow:
The one Im talking about would be right after the 68k to ground right at the tube. On that schematic I will look.
Bill
PS SG I really like the small footprint you have on this one with a high gain channel to.
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Ah ok, but it is used for blocking DC. Thank you, learning a lot here but there is so much
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Ah ok, but it is used for blocking DC.
No.
A blocking cap is in series and acts like a gate that blocks the dcv but lets the ac signal through.
The cap their describing here is bleeding hi-freq. to ground, so it's not 'blocking' anything, nor is it coupling anything.
Brad :icon_biggrin:
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Thanks for taking care of lego's question guys.....I was away from the computer.
I actually have a cap like the one Willabe describes, in this amp...
It's between stages and I believe it helps to shunt some highs.
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I do get it now, thank you. I down loaded Jack Darr's book but I also bought one. I wasn't printing all that out and I like having books to read
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Sorry guys I meant to post a schematic so we could see it. I couldn't find one last night exept for Merlins book and I didn't think it would be proper to post the page. and then I got sidetracked.
Thanks SG that's exactly like I was talking about except on V1a right after the 68K. Both of them same function different spots.
Bill
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I'm using Doug's relay board and PS board, and haven't nailed down the location of the power supply board....I have plenty of available heater current.
It could go at either end of the chassis depending upon where I should tap the filament run for power. (will mount on the inside of either end-cap)
Is there a more preferred spot so as to minimize potential noise?
Should I tap it right where the 6.3 comes into the chassis or at the other end of the filament run ,,,after the first preamp tube?
I imagine if I put it after the first preamp tube that I run the risk of hearing it. :dontknow:
Is there any known associated noise problem at either location?
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OK, now it's on.....Flyers are out, and I can concentrate on getting D-O-N-E
Is it OK to tap the filament string as a parallel branch to run one relay PS board, or should it be in series?
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It must be parallel just as shown in your schematic. I'd tap into the string at pins 2 and 7 of that first brown socket and put the power supply on the left end of the chassis (as seen in the photo). I'd also try to mount the relay board near the circuit that it will actually be switching in order to avoid long runs of signal wires. In fact, if this will be a turret board construction, I'd just put the relay socket and diode directly on the main turret board. I understand this may be a challenge in that long skinny box! :icon_biggrin:
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Your lose my gain, now its Penguin hunting time. This Relay stuff is interesting, never knew they were in amps
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silvergun,
In the diagram, where you show caps on the cathodes, It is my understanding that the fully bypassed cathode helps the gain on the tube. Gurus let me know if I am wrong.
That is correct Dr., but I'm no guru.
The gain through the stage is frequency dependent on the value of those caps...
I see the 4.7uf on V1a as "mostly" bypassed, and the .47uf on V2a to be only partially bypassed which will help serve as a treble boost for that stage by shifting the response up in frequency.
Fully bypassed stages in high gain amps can make for "woofy", loose, sloppy, bass response....
One of my ah-ha moments on the breadboard was when I realized how to "shape" the signal by using different value caps in conjunction with different value cathode resistors to create desired boost points throughout the signal path.
Merlin has a great description of this function (along with a chart that opened my eyes) on page 26 of this chapter in his preamp book that you can download for free here: http://www.valvewizard.co.uk/Common_Gain_Stage.pdf (http://www.valvewizard.co.uk/Common_Gain_Stage.pdf)
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Sgun; nice work. your builds are starting to shine like a diamond in goats ass. keep up the good work. :icon_biggrin:
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Sgun; nice work. your builds are starting to shine like a diamond in goats ass. keep up the good work.
Well smack-o,,,that's the nicest thing anyone has said to me in a while :undecided:
Maybe I'll name it Diago? :think1: short for - Diamond In A Goats Opening
Ooops,,,nope,,,somebody beat me to it:
http://www.diago.co.uk/guitar-amps/little-smasher.html (http://www.diago.co.uk/guitar-amps/little-smasher.html)
:icon_biggrin:
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Sgun; nice work. your builds are starting to shine like a diamond in goats ass. keep up the good work.
Well smack-o,,,that's the nicest thing anyone has said to me in a while :undecided:
Maybe I'll name it Diago? :think1: short for - Diamond In A Goats Opening
Ooops,,,nope,,,somebody beat me to it:
http://www.diago.co.uk/guitar-amps/little-smasher.html (http://www.diago.co.uk/guitar-amps/little-smasher.html)
. :l2:
:icon_biggrin:
Ok now thats funny. Diaga sounds better anyway ,everyone would ask what it meant. :l2:
Bill :icon_biggrin:
Guess I found the name for my new amp line.
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T.J.,,,(or anyone else for that matter)
I know you're a bit of a tube roller...
Any suggestions on a good choice for current production EL34's to "try" in this ultra high gain setup?
I've been using Winged C's on the bench and would probably just put them in the amp, unless something stands out as a better choice.
I'm just over 500volts on the plates and in the 490's on the screens, so I appreciate the Winged C's 500 volt screen rating. (they held up on the breadboard)
OT primary is 3.6K for 2 EL34's
The player is looking for a soup'd up "old school metal" tone, and I don't have a lot of experience with different power tube types.....or a lot of spare cash to throw around.
I was also considering adding a dropping resistor in series with the 5Hy choke to try to make sure the screens stay in check.
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Let me be the first to congratulate Tone Junkie on his new Goat's Ass amp lineup. Simply marvelous stuff!
Sgun; I don't know a lot about current prod. 84's but I love the Sovtek WXT6L6 tubes. Mucho power and great tone. Here is a link to their EL84 tubes. I also hear most guys using the JJs but that may be for price point .... don't know fo sho.
:icon_biggrin:
https://www.tubedepot.com/products/sovtek-el84-power-vacuum-tube (https://www.tubedepot.com/products/sovtek-el84-power-vacuum-tube)
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Sgun; I don't know a lot about current prod. 84's but I love the Sovtek WXT6L6 tubes. Mucho power and great tone. Here is a link to their EL84 tubes. I also hear most guys using the JJs but that may be for price point .... don't know fo sho.
34's smack-o.....please quit laughing about the goat's ass long enough to pay attention :l2:
https://www.tubedepot.com/products/sovtek-el84-power-vacuum-tube (https://www.tubedepot.com/products/sovtek-el84-power-vacuum-tube)
Let's get rid of that link....I try to avoid linking to Doug's competition as much as possible....I know where to find them, just looking for opinions.....and thanks for the bit about the WXT6L6's ...I'll hang onto that :thumbsup:
:icon_biggrin:
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I decided to mount the OT inside the cabinet by bolting it through the front baffle.
Do I have to ground the frame of the OT to the aluminum chassis?
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SG Im not really knowledgable about differant EL34 applications in the 490 range. last amp I made with the voltages that high, I put in 6550 out of worry. I had 2 pair of the winged C and wanted to keep them and that was one of the only ones people were saying would take that kind of voltage. but I havnt checked concensus lately.
smackoj Do you think my buisness plan will work. put out one diamond in a goats ass every 2 or 3 month,s maybe get market saturation 20 or 30 yrs. (LOL) brand recognition maybe 50 :l2: .
Bill
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I fear you now have a "wheel in the ditch".
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If you really are serious, I have some that EL34's that will work just fine. The 6550 is a good selection, but I have ran servicemaster internationals at higher voltages and would in a minute in a headbanger amp. Problem is, where are you going to keep getting them? People swear by JJ's but I have toasted many nearing this voltage. Fact is even the old =C= I would not trust. I got some of the old ones to get you running for a while, but therein is the problem. Where to get new ones?
I would try 6550, which I use for this application. You will not lose and forcefulness in the mids and if Heavy Metal is what you are going for, how can something with more bottom be wrong. They certainly are not going to be a cleaner sounding tube. If you don't care for the 6550, just buy a lot of EH as they have a good tone.
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I fear you now have a "wheel in the ditch".
UH-OH!
WhattdidIDOOOO? :dontknow:
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If you really are serious, I have some that EL34's that will work just fine. The 6550 is a good selection, but I have ran servicemaster internationals at higher voltages and would in a minute in a headbanger amp. Problem is, where are you going to keep getting them? People swear by JJ's but I have toasted many nearing this voltage. Fact is even the old =C= I would not trust. I got some of the old ones to get you running for a while, but therein is the problem. Where to get new ones?
I would try 6550, which I use for this application. You will not lose and forcefulness in the mids and if Heavy Metal is what you are going for, how can something with more bottom be wrong. They certainly are not going to be a cleaner sounding tube. If you don't care for the 6550, just buy a lot of EH as they have a good tone.
I'm not against permanently mounting a bucking xfmr in this thing if I have to drop some V's
Truth is, I built the amp on the board with 350VAC feeding the rectifier, and now that I have the PT in there the voltages I'm seeing are higher,,,but with no load...
I'll have to see how far it drops when everything's up and running...
Problem is I got a big 'ole PT and I'm afraid it aint gonna budge a whole lot :embarrassed:
Wont know til it's fired up.
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I fear you now have a "wheel in the ditch".
UH-OH!
WhattdidIDOOOO? :dontknow:
I decided to mount the OT inside the cabinet by bolting it through the front baffle. Do I have to ground the frame of the OT to the aluminum chassis?
I think he's saying you might have problems with the OT wiring now being too long.
That's what I'd be concerned about.
Brad :w2:
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I think he's saying you might have problems with the OT wiring now being too long.
That's what I'd be concerned about.
OK,,,I'm a big boy.....I can take it :icon_biggrin:
I've wasted more time on this project trying to adapt to a non-standard layout,,,, that another couple hours won't kill me.
The suspense might....
Willabe, could you ask sluckey what he's seein? :wink:
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I'm seeing a part-part here, a part-part there, here a part, there a part, EVERYWHERE a part-part....
I think you have figured out how to stuff your breadboard in a combo cab! :icon_biggrin: Not sayin' it ain't gonna work, but if it doesn't, it's gonna be a beetch to troubleshoot.
The engineers at Sears would be proud. :wink:
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I think you have figured out how to stuff your breadboard in a combo cab!
:l3:
That's exactly what I started to think to myself the other day.....maybe MY line of amps is just a line of breadboards :icon_biggrin:
I just hated the idea of hanging anything heavy off of that flimsy chassis....and I let that dictate some of my choices...
It has cost me more TIME than I would ever have imagined to build this way.....this is my one big mistake that will make me stronger and smarter for the future.....everybody gets one big one, right?
If it works, then I knew it all along and there was never a doubt :angel
What do you think about grounding the frame of the OT?....I was just curious as to whether it is a must for electrical safety or noise suppression or both.
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everybody gets one big one, right?
Oh no. We all get ONE AT A TIME. Repeat as necessary. :l2:
What do you think about grounding the frame of the OT?....
I don't think there will be any benefit, but I'd probably do it. What did you do with your PT?
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If you really are serious, I have some that EL34's that will work just fine. The 6550 is a good selection, but I have ran servicemaster internationals at higher voltages and would in a minute in a headbanger amp. Problem is, where are you going to keep getting them? People swear by JJ's but I have toasted many nearing this voltage. Fact is even the old =C= I would not trust. I got some of the old ones to get you running for a while, but therein is the problem. Where to get new ones?
I would try 6550, which I use for this application. You will not lose and forcefulness in the mids and if Heavy Metal is what you are going for, how can something with more bottom be wrong. They certainly are not going to be a cleaner sounding tube. If you don't care for the 6550, just buy a lot of EH as they have a good tone.
I'm not against permanently mounting a bucking xfmr in this thing if I have to drop some V's
Truth is, I built the amp on the board with 350VAC feeding the rectifier, and now that I have the PT in there the voltages I'm seeing are higher,,,but with no load...
I'll have to see how far it drops when everything's up and running...
Problem is I got a big 'ole PT and I'm afraid it aint gonna budge a whole lot :embarrassed:
Wont know til it's fired up.
Well you don't want it to budge much. My 1 metal amp is stiff and needs to be. It too is running el34's and I did have to bring down the voltages as I was toasting tubes, but not any good ones. I did not really know what the topic had steered to. I understand what the deal is not, what I do not understand is why you used that chassis? Not throwing stones, just dirt clods. I mean you are building an amp that should standup. It is not a wedding band amp, correct? :l2:
Are you not a big wheel at a welding machine shop? Certainly someone there can weld.
Oh well, you raise them to act right then they go and do stuff like this. :dontknow:
I will go back in my hole now, but not before I say I prefer in new production EH El34's. The highs are similar to old mullards, they just do not have the beef.
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What did you do with your PT?
Grounded the frame by bolting through that alum. angle where the power connector is. Power connector is grounded at that same point.
I did follow all usual grounding procedures, and have the first 2 filter caps there as well as the 6.3v CT and negative connection off of the bridge rectifier.
The last step will be to ground the chassis box to that same angle by bolting through and using a short length of braided ground wire.
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why you used that chassis? Not throwing stones, just dirt clods. I mean you are building an amp that should standup. It is not a wedding band amp, correct? :l2:
It's for a GIRL :huh:....and she rocks :guitar1
She asked me for a 2x12 combo, and we talked about weight and size, and this was MY bright idea....
After reading all the horror stories of all of you guys.....I took it upon myself to swim upstream...
All I do now is walk around shaking my head and muttering "nevvver again"
It will work....failure is not an option. period. (that's what I tell myself as I'm crying myself to sleep)
And next,,, I'm gonna order a Champ kit :icon_biggrin:
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Here's an update pic...
The relay power supply squoze nicely into that corner, and you can see where the entrance connectors come into the chassis for the OT connections, and attach right to pin(s)#3 with a little buss wire...
Sluckey was right about me not being able to reach the chassis mount screw hole that I had predrilled.....(I mean ventilation holes that I meant to put there ):wink:
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Hey SG,
Since you are doing all this wonderful "tone shaping" on the preamp side, do you really want to color it with EL34's limping along in the small joints or crunching when she turns it up for an outdoor gig? You might get good results - but then again...
Like Ed, I am not a fan of 6550's. Why not use some KT88's in the power section? Typically a nice bold response that really does not change unless you nail them to the wall. They would live a long life at those voltages and faithfully reproduce all the cool things you are doing in the preamp. Just a thought.
Also, it's a good thing you mounted that output tranny next to the speakers. Those short speaker runs are perfect. Line loss would be terrible had you mounted it on the chassis. Cant let anything get in the way of that smooth funk/jazz you keep telling me about.....
Jim
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Since you are doing all this wonderful "tone shaping" on the preamp side, do you really want to color it with EL34's limping along in the small joints or crunching when she turns it up for an outdoor gig? You might get good results - but then again...
Like Ed, I am not a fan of 6550's. Why not use some KT88's in the power section? Typically a nice bold response that really does not change unless you nail them to the wall. They would live a long life at those voltages and faithfully reproduce all the cool things you are doing in the preamp. Just a thought.
Well,,,I went 2-EL34 probably mostly because of a lack of vision.....call me a sheep. I honestly didn't realize that these voltages would create this much of a problem. Got the 50 watt JCM800 OT @ 3.6K and didn't even think twice about it. :rolleyes:
Plus they're all I've got here....being new into tubes comes with some unfortunate downsides......I haven't been collecting tubes for the last 20 years :embarrassed: , so my cupboard is pretty bare.
And I wanted to give her the option of being able to pick up a spare set at Banjo World in a pinch.
Got the 100 watt PT because I don't believe in running PT's warm/hot (comes from welding machines where I've seen the effect of insulation breakdown), and didn't realize how high the V's would be with no load. duh.. I'm used to 500 AMP loads so milliamps don't add up in my head yet.
I'll see how it goes when it's all fired up, and where my voltages are under load...
I did voice the amp around the ELs, so there's something there I like,,,,I never realized that the screen ratings were so low until I started shopping around for the "right" pair.....the Winged C's never lit up once, and I bang'd em around pretty hard soooo :dontknow:
The KT88s might be in MY future....I hear they pull off a nice smoothjazzsoftsoulfunk lead tone like no other.
In a pinch, there's plenty of room in the base of the cabinet for a bucking xfmr.....I just feel kinda silly putting one there when I just spec'd out the PT for this thing......dummy :sad:
Maybe some day I'll grow up and stop putting all of the focus on the preamp, and payafukintention to the other important details.
You don't know what you don't know until you know you don't know. :BangHead:
This is how we learn.
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Methinks you are too hard on yerself! There are certainly many sonic ways to skin this cat. I was just thinking about a tube that can live a long full life at those voltages.
What? No reply on the short speaker leads? I'm disappointed!
Jim :icon_biggrin:
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What? No reply on the short speaker leads? I'm disappointed!
I thought I picked up on some sarcasm there?.......but somewhere around post #70 I think I may have lost some of my sense of humor, and didn't get the joke. :dontknow:
That's right about the time I figured out this wasn't such a "brilliant" idea. :BangHead:
- Funny thing is, when sluckey made the "wheel in the ditch" comment and Willabe followed up with his thought about the OT wires possibly being too long,,,,I wanted to punch myself in the face for taking something from another thread out of context and making it into an instant "rule of thumb"
..Over on the AC15 thread, Ed had asked sluckey if there was any reason to keep the OT wires short,,,and sluckey replied "no, just keep them away from the preamp circuit"
.....so in my really big, empty head, that registered as 'there is never any reason to worry about the length of the OT wires' :rolleyes:
....AND, so that's how I came to the conclusion that I didn't have to pay any attention to the placement of the OT, or the length of the wires.
I can't wait to fire this thing up just so the troubleshooting can begin. :thumbsup:
LC
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I was just taking a guess about what Sluckey meant. :dontknow:
You are spreading things out but I don't know how long you OT wires will end up being.
I think Sluckey hit it on the head thou, about figuring out how to put a bread board in a combo speaker cabinet.
Hey it's an idea, you tried it, maybe it'll work, maybe not. Not the end of the world if it doesn't. Not the 1st time that has happened here and wont be the last.
Hit 3 out of 10 plate appearances and your a star and make millions, but that's 7 failed attempts.
Get your peanuts here, Red hot's, get your Red hot's here. :laugh:
Brad :icon_biggrin:
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I was just taking a guess about what Sluckey meant.
I know...and I always appreciate the help... :thumbsup:
This one's all me.... :sad:
After this I will never try to reinvent the wheel again.....I promise. :angel
I won't be able to blame anyone but me if this doesn't fly....and that's the way I like it.
Hit 3 out of 10 plate appearances and your a star and make millions, but that's 7 failed attempts.
OK....I like my odds on that!
Maybe I can be a superstar!? :grin:
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OK....I like my odds on that!
Maybe I can be a superstar!? :grin:
Sure can! :undecided:
Beer here, get your ice cold beer here!
Brad :m2
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3 out of 10 may make you a superstar in Chi-town. We have higher expectations here in a REAL baseball town....
Jim :icon_biggrin:
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Yeah, yeah, :l2:
I told you not long ago, "It's gonna be a LONG summer in Chgo".
And the home plate ump says, Play Ball
Cracker Jacks, get your Cracker Jacks here!
(Yadiar Molina! Boooooo!!!!!, best catcher AND 1 of the best hitters in the Majors! I tip my blue Cubs hat, he's the real deal!)
Brad :m2
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Well,,,I went 2-EL34 probably mostly because of a lack of vision.....call me a sheep. I honestly didn't realize that these voltages would create this much of a problem.
Just finish the amp. It worked on the breadboard, will probably work in the amp.
If it doesn't, you will have learned something and can adjust-fire from there.
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Yeah, what he said!!!!
You must remember that those of us with time/schedule/family/financial/ability/etc./etc.... constraints are living vicariously through you! And unlike Chicago and Philly, we don't boo our players, we cheer them on! Well, yeah, we do give them crap from time to time to keep them honest.... :icon_biggrin:
Jim
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You're gonna need a standby switch on that amp. In keeping with the general theme, may I suggest something like this? Mount it on top of the cab and it can double as a tote handle... :wink:
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You're gonna need a standby switch on that amp.
He's got one... in the ash-tray on top! Handy place to put your cigarette, too! And if the amp catches on fire, you've got a ready place to pour the beer...
Actually, I think the location and embodiment of the standby switch could be a cool feature. It's no on the back where it might be hard to reach on stage, and it's recessed so it won't get sheared off when the combo gets thrown into the van. It's not in the way if you pech other things on top of the cabinet.
Perfection might be the sealed switches intended for marine (or military) use, but those are probably more $$$$$$ than they're worth in this application.
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You're gonna need a standby switch on that amp. In keeping with the general theme, may I suggest something like this? Mount it on top of the cab and it can double as a tote handle...
:l2: You're killin' me.... sorry I didn't think of that first....It'd go right along with the theme.
He's got one... in the ash-tray on top! Handy place to put your cigarette, too! And if the amp catches on fire, you've got a ready place to pour the beer...
Actually, I think the location and embodiment of the standby switch could be a cool feature. It's no on the back where it might be hard to reach on stage, and it's recessed so it won't get sheared off when the combo gets thrown into the van. It's not in the way if you pech other things on top of the cabinet.
Good catch HBP,,,,I'm glad to see someone's paying attention.
I did actually think it through and found those same positive attributes.....
That was one of my crowning achievements, when I decided that this thing was going to be unapologetically different...
Getting past the idea of running a hole saw down through the top of my beautiful new cabinet was like ripping off a Band-Aid.....
I measured 6 times and drilled once, because that's what all good hack carpenters do. :icon_biggrin:
Here's a shot of the "ash tray"...it's a Cole Hersee truck part, and unfortunately the chrome isn't as nice as I would've wanted...doesn't really match the corners, and looks more like galvanized than chrome........character,,,that's what I tell myself. :laugh:
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Alright.....I realize I have one major personality flaw...
I only like to disclose things that go well and when something goes wrong I clam up and work through it.....
Well, I had a near death incident the other night when I found out I wasn't getting filament V to one of my power tubes.....
I almost shoved my 800 degree soldering iron up through my nasal cavity and straight into my brain to stop the pain of what I found....
Even though I WAS getting 6.3vac on the inside of the chassis at the socket,,,,when I removed the tube and shoved my meter leads into the holes for pins 2 and 7 ....NOTHING :huh:
So I shut off the power and started poking around and the #7 pin connection just broke right off as soon as I touched it with a pair of needlenose.
SO I must now replace both sockets because I bent the pins back the same on each one.............. :BangHead:
The good news was that right before this brick wall showed up, I had perfect voltages everywhere else and was ready to hear it roar...
Only problem was that one EL34 was much darker than the other,,, and I had 0mv cathode current reading there.........you can't beat 'em if you don't heat 'em.
So here's my rant...
Are you kidding me???
I used Belton octal tube sockets because I had them here and they looked pretty heavy duty......except for the part I couldn't see which is the TINY little pin that connects the inside socket terminal to the outer solder tab (pictured).....why does that tab taper down to 1mm (so it can break?)
I had attached the filament wires and then bent the tabs back to get them out of the way.......REALLY BAD IDEA, because it snapped right at the bend!
I don't have this kind of time in my life.... :sad2:
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Bet all the recent heater discussion really paid off. Ain't you glad you didn't use the Soldano wiring method? :wink:
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Bet all the recent heater discussion really paid off. Ain't you glad you didn't use the Soldano wiring method? :wink:
I will tell you what. You really give it you all. It would be no problem for me to change it out, cannot see why it would be for someone of your caliber. :laugh:
Not slippin since retirement are you?
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Bet all the recent heater discussion really paid off. Ain't you glad you didn't use the Soldano wiring method? :wink:
Yes....that stuff is just for looks anyway,,,, and I'm not wasting my time on such trivial pursuits anymore...
I've got amps to build.
It would be no problem for me to change it out
Yeah, me either, except I didn't have anymore here.... I do have about 6 of the ceramic ones that Doug sells and obviously should've just used those in the first place.......
So that's twice burnt now....
-Once with the conductive black board that I didn't get from Doug
-And now this...
This just goes to show.....get everything from Doug or the amp gods will rain terror down upon you. :sad:
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You've obviously never been inside THAT chassis. I've been inside three of them. I know what I'm speaking about.
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You've obviously never been inside THAT chassis. I've been inside three of them. I know what I'm speaking about.
Yes, I just about made that mistake, remember? I built one of those AB763 in a deluxe cab and you told me about how thin the thing is and how tight it is. I did listened didn't I?
OTOH, I did forget you are just regurgitating what you mentor Gerald Weber taught you. :l2:
Now that's funny!
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You've obviously never been inside THAT chassis.
UGHhh.....seriously painful.....like trying to cook a turkey in a toaster oven....just dumb
So I switched gears and made a backer board for the grill cloth....
I'm really enjoying using a router with a circle cutting guide to do holes.....thinking about opening a side business using the cutouts and selling stools :icon_biggrin:
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I had attached the filament wires and then bent the tabs back to get them out of the way.......REALLY BAD IDEA, because it snapped right at the bend!
Now you know. Those pins aren't made to be bent like that. At 1st I just thought you had a bad 1.
And now you know to check the socket from the top side if you still can't get heater voltage.
Your building a library in your mind filled with hands on experience, that cost, time. Such is life.
Your being to hard on your self.
Brad :icon_biggrin:
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Have you fired this up yet?
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Have you fired this up yet?
Not since the socket went....
I didn't realize that the ceramic sockets would fit right into the same holes I punched for the Belton's (the Belton holes are bigger, but the ceramic sockets have these little wrap around wings that seem to fit the hole OK)
I was so mad that I had to back off. :wink:
I'm hoping to have both sockets replaced tonight.
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WOW!!!
IT IS ALIIIVVE!!!!!!!!!!!!!
:happy1:
Very little issues to overcome....
Big, bold, bad-ass....better than it was on the breadboard, because I'm not competing with noise...
I can't stop playing it long enough to type anything of any real substance,,,but I'll say this...
Our concerns have been erased!
I'll plan on doing some recording tomorrow night :headbang:
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I snapped this pic on the way out the door, from my phone so my wife could see what the "problem" is... :icon_biggrin:
Sorry it's out of focus :sad:
sluckey, you can see where I mounted the relay directly behind the front panel switch,,,,and the footswitch jack is right there on top as well so all of the wiring was pretty tight....
I'm very excited about how this turned out!.....and a little surprised :wink:
Still some work to be done,,,but the sound is there :grin:
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Bravo SG congrats on the good looking amp. :icon_biggrin: I love a good high gain amp so I'm green with envy.
Bill
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I never doubted you for a minute. Actually looks very good. That little Hammond is really stuffed! Good job.
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:bravo1:
Nice work. Lots of preamp tubes and I will bet none are for reverb or tremolo. :icon_biggrin:
I agree, you have a ;ot crammed in that chassis. A couple of speakers and you will have the Fire Cube.
I truly love El34's. Great Job!!!
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THANKS GUYS!!
There's that moment when you flip the standby switch and you have a moment of silence because you haven't moved any of the controls off of zero,,,and then slowly you bring up each control until you have a sound,,,and then you turn the important ones towards 10 and wham,,,the moment of truth.
Well, it works,,,, so I can get to work figuring out where I made a couple small mistakes....we'll talk about those in a bit...
I'm working on cleaning up the schematic, and scanning in my sloppy, scribbled layout pages, that I wouldn't suggest anyone else follow..... :l2:
I've got 2 boards in there,
One that's directly over the preamp tube sockets, as a "power board", with holes cut out around the preamp tubes, where the plate supply comes in and the cathodes go to ground...
And the a "signal board" where everything else is mounted...
Pics coming in next post.
Nice work. Lots of preamp tubes and I will bet none are for reverb or tremolo. :icon_biggrin:
I agree, you have a ;ot crammed in that chassis. A couple of speakers and you will have the Fire Cube.
It's only been a short amount of time ,,,but you know me....
Although I do like reverb and tremolo,,,they weren't called for here,,,so that left me plenty of room for high gain...
"Fire Cube" sounds like a good name....maybe I'll mount a fire extinguisher in the bottom of the cabinet. :laugh:
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I realize that this is all out of order, and maybe I should eventually make a new thread,,,
But here's a shot of the "signal board" for anyone who's curious....
I have adopted the technique of wrapping the component leads around the turrets, for a mechanical connection, and leaving the tops of the turrets open for inserting wires....it just works for me
Under the board pic I attached my hand drawn layout for that board....it was full size so I had to paste it together and reduce the size to get it to fit, but I think it's ok and pretty accurate....
Sorry for the scribbled mess,,,but that's as far as I go with my graphic design at this point. :icon_biggrin:
EDIT--I had to crop it down to fit under the file width limit.
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:nice1: SG, I've been down after a little shoulder surgery and find this thread with great interest, amusement, and enjoyment. Just what I needed as I'm just beginning to hold a guitar & a soldering iron again. :happy1: All the regs have showed up with their 2cents too and the diamonds in a goat's ass is hilarious. Too bad that little Diago amp had to be out there. I love it. Ed, classic - (what the heck does he have scheming now?). Also, it appears SG & Ritchie are playing nice aside from corncobs? :l2: warms a person's heart. Willable you kept the focus of this thread going well, I'll take a hotdog and a beer please! And Samardjia too while you're at it. I live the land of Trout and Pujols :angel and we could use a young gun like him.
I've had the ol' filament issue before and is why the pre-checking as you go is always a good practice isn't it? Stitch in time...but you were sort of double hoodwinked with that cheap-ass pin design. The extended OT wiring can carry lots of current and mess things up but doesn't appear to be an issue!? You really did something here SG in thinking outside and inside the box which I really appreciate and applaud, not that you need my approval or anything.
So one of my big questions is does this have any semblance to your holy grail Bogner Ecstacy pre in it? Inquiring minds wanna know. I also didn't see but one potential voltage divider aside from the pots of course so wondering if you've tried the split plate load resistor technique or not? Sorry, I've been a bit out of the loop as it's been a little hectic the last couple of months but I still drop in for a couple bottom turns when I can peeking through the green room.
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You really did something here SG in thinking outside and inside the box which I really appreciate and applaud, not that you need my approval or anything.
And I really appreciate your praise my friend....there's no way that I'd be this far along without your initial help and direction, and I truly THANK YOU for all of your help and support on and off the forum. Thanks for taking the time out of your life to share this gift with me.....priceless!
So one of my big questions is does this have any semblance to your holy grail Bogner Ecstacy pre in it? Inquiring minds wanna know. I also didn't see but one potential voltage divider aside from the pots of course so wondering if you've tried the split plate load resistor technique or not?
Yes and yes...Bogner is in there and I did try the split plate load stuff, but it's not in this design...
The schematic is coming just as soon as I can get it cleared up and looking like something I would want to look at.
It took 2 months of on and off tweaking, with the help of a couple of local players to get this to where it is, so the schematic had to be reverse engineered from the resulting breadboard layout......
And it was noisier than a room full of soccer moms when it was on the breadboard,,,so I was a little scared about trying to jam it in this box....
So that's when I got the big idea to separate the boards, and try to separate the preamp tube current from the signal....and just give myself more room to work.....that's where some of my "innovation" bit me in the ass, because I spent more time trying to not make a mistake, while not following any other template.
But we got here, and now it's just finishing touches...
There are a few small problems to overcome, but it's got the monster tone, and it is gonna fly.
This is as far as I could imagine anyone would ever need to push gain, and I'm still shocked that what comes out of the speakers doesn't mush up or get "blocked"
The clean channel is based on the 5E3, but also shares the 'tubenit style' active effects loop which adds some gain... so it's hard to call it clean at all....but that's ok, because 'she' doesn't care...it would actually qualify as high gain for most guys that consider a half-cranked T-wreck as high gain....
I did LED cathode bias on the one triode that is dedicated to the clean channel, and that LED is mounted near the input and also acts as a standby power indicator....when you take the amp out of standby, the 1.7v drop across that LED causes it to light and that's how she'll know it's time to ROCK!
(thanks to sluckey, Merlin, tubenit, HBP, etc., etc.,)
This project started because I took the Sovtek/Bogner head into a local store and a couple of the guys were raving about it....
But this girl kinda stood back, and said it wasn't her thing.....too bright, not enough gain :huh:, not enough d'jent (look it up, it's an actual word)
And I asked her to show me what she meant, and she plugged into a Marshall JVM series and proceeded to rip my face off....and my BIG MOUTH opened,,,and I said "Yeah, I can do that" :undecided:
So I researched the 'Greatest Metal Amps' and "borrowed" every single schematic I could find and stared at them for about a week...and thought to myself "You could do that".....and that's when the breadboard came in very handy :wink:
The high gain channel is a culmination of everything I have "learned" :wink:
It is VERY bass heavy, and shares a modern NFB 'contour' control that compresses everything and tightens it up to the point of feeling like a completely different amp at one end of the dial to the other.
If you've ever wanted to push the outer limits of the highest of high gain, with no pedals in front.....this might be it. :dontknow:
It would be very easy to bring some highs back in if it turns out to be too dark.
Also, it appears SG & Ritchie are playing nice aside from corncobs?
Yup,,, Ed, sluckey and Willabe vouched for him so now he's OK :icon_biggrin:
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I know he's just hiding in the bushes until I post a sound clip....then we'll see how "nice" things are.
I don't think that's true, I think he's been very encouraging to you and has been complementing your work and ideas. He's for you and your builds.
And Ed, he's just goofin around with you a little. He's in your corner too.
Brad :icon_biggrin:
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And Ed, he's just goofin around with you a little. He's in your corner too.
We all are. But when you step that far outside the box you gonna get a little ribbin' from people who like you.
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he's been very encouraging to you and has been complementing your work and ideas. He's for you and your builds.
We all are. But when you step that far outside the box you gonna get a little ribbin' from people who like you.
I know,,,and I'm very lucky that you guys have accepted me and ALL of my "Philly" ways
Check the edit,,,,some day I'll learn when to 'leave well enough alone' the first time :wink:
Rib-away :l2:
I knew this was gonna work all along..... :undecided:
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We all are. But when you step that far outside the box you gonna get a little ribbin' from people who like you.
Yes, much better said!
Brad :m2
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WOW!!!
IT IS ALIIIVVE!!!!!!!!!!!!!
:happy1:
The main chassis turret board and wiring looks great! And it fly's!
Very Nice!
Brad :icon_biggrin:
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:nice1: SG, I've been down after a little shoulder surgery and find this thread with great interest, amusement, and enjoyment. Just what I needed as I'm just beginning to hold a guitar & a soldering iron again. :happy1:
Glad your feeling better jojo and yes, I agree, very nice thread. :icon_biggrin:
SG took a chance at thinking outside the box and did manage to land on his feet. :dontknow: :laugh:
Nice work SG! :bravo1:
I'll take a hotdog and a beer please!
You got it! You know in Chgo, mustard, NO ketchup!
But, wait, what, no Cracker Jacks? You do know there's a prize in every box? :undecided: :laugh:
And Samardjia too while you're at it. I live the land of Trout and Pujols :angel and we could use a young gun like him.
Nice, our best pitcher, come and pick our bones please. :BangHead: :cussing: :laugh:
Brad :icon_biggrin:
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Hey SG, now that the amps sounding fine and flying high, has it stopped raining there yet?
Bet it has.
Brad :icon_biggrin:
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BLAH BLAH BLAH YEAH YEAH very nice ............................
TUNES man TUNES, SG...SG...SG............................
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BLAH BLAH BLAH YEAH YEAH very nice ............................
TUNES man TUNES, SG...SG...SG............................
:l3:
Brad :icon_biggrin:
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Ok great, I cannot see much in your drawing. Tonestack looks very Marshall like, but is that a 68K slope? Cathode driven?
What is your OD circuit and where are you inserted? Is the OD switchable or simply part of the dirt channel? I assume 12AX7 to 12AX7?
What EL34 plate voltages?
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SG,
You've done a VERY cool thing here with this build! Coloring waaayyyyyy outside the lines and with success. Bravo!
Look forward to sound clips.
With respect, Tubenit
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SG - you're too modest and deserve all the accolades. Nobody can just short-cut their way through all of the things involved, the learning, the learning process (aka school of hard knocks), etc. it all takes a lot of time and dedication unless one has the non-volatile RAM memory of a CPU chip? So take all the credit deserved for not just learning at a rapid pace but while adapting & improvising along the way too!
Sluckey hit the nail when he described it perfectly as a breadboard amp or was it "Old McDonald's Farm"? :laugh: To me it's more like Young Frankenstein since it's rather Abby Normal in it's building but since it was made for young woman it seems more fitting as the Bride of Frankenstein or simple Frankenbride? Even go with lightening bolts running across each side of the cab (see photo)? But call her whatever you want SG...I'd love to eventually hear this thing being played by the lucky red hot female shredder of which you speak of??? That would be really cool.
Willabe - definitely no Ketchup or Catsup or whatever red stuff unless maybe it's Tabasco or some other hot sauce??? Now we're talkin' gourmet dogs??? I've been eating Craker Jack since I was knee high to a grasshopper but the surprise inside ain't what it used to be. I've heard speculation that the Cubbies are going to be sellers soon with Jeff's name being dropped but you never know? Epstein is no dummy and could get a few quality guys in return.
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SG,
You've done a VERY cool thing here with this build! Coloring waaayyyyyy outside the lines and with success. Bravo!
THANK YOU Sir,
You have been a HUGE influence on me and my desire to not just take the easy path.
I have learned a TON by reading your threads and questioning everything.....and because of that, this is much more enjoyable for me than if I was to just build a couple kits and be done.
This is now a lifetime hobby that I can plan to take into retirement,,,even if that is 20 years away :icon_biggrin:
Ok great, I cannot see much in your drawing.
Sorry,,, that was just meant to show you what was on that board,,,and how I work off of chicken-scratch drawings :icon_biggrin:
I'm still working on the preamp schematic, but I'm very close.....it will take care of most of your questions.
Haven't even started the power amp page, but the only thing special there is the NFB filter circuit, which is connected to the 'contour' control, and is a serious scooping device.OD channel is a tweaked Bogner, all 12AX7, cathode driven tonestack, 68K slope......nothing really all that special, except a 470K resistor between the treble pot and the OD volume, that is worth noting....
I'm not sure exactly how it works but it definitely cuts some highs and seems to change the overall dynamic between the treble and bass controls.
It was one of the tweaks I found to cut some highs that she didn't want.
I wrestled with grill cloth for about an hour last night, so I didn't get anything recorded,,but I plan to dedicate some time to it tonight,,,TIMBO :icon_biggrin:
Here's another shot of some high quality chicken scratch from early in the process :huh: (just for laughs :l2:)
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Hey SG, now that the amps sounding fine and flying high, has it stopped raining there yet?
Bet it has.
You know,,,that's been one of the toughest parts...
Spring has sprung, and it has been very difficult for me to stay inside and get this done,,,even if it is after work.
Sometimes I'm here working alone and thinking "I'm the only idiot in the world who is doing THIS right now"
But then I saw what Ed, lego and sluckey have been up to and that has helped fuel the fire.... :thumbsup:
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Here's a pic,, and my last known drawing of the power board layout....a couple values changed since this drawing, including the LED cath. for V1b (not pictured)....I replaced the 10uf/ 2.2K cath. on the second stage with the red LED that Doug sells in the little chrome housing.
I just figured you guys would find this stuff amusing, if nothing else :icon_biggrin:
Again,,,I would not try to duplicate this, because I was fixing things on the fly, so this is definitely a "one off"
If I had to do it again, I would put the grid leak resistors on the power board, and attach the grid stoppers right to the socket pins without using turrets.
THAT might actually be a cool thing to try.
This board makes the amp very difficult to work on, and whoever has to replace a preamp socket is gonna want to pull my jersey up over my head and take a 5 minute major. :icon_biggrin:
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Here's a pic,, and my last known drawing of the power board layout....a couple values changed since this drawing, including the LED cath. for V1b (not pictured)....I replaced the 10uf/ 2.2K cath. on the second stage with the red LED that Doug sells in the little chrome housing.
I just figured you guys would find this stuff amusing, if nothing else :icon_biggrin:
Again,,,I would not try to duplicate this, because I was fixing things on the fly, so this is definitely a "one off"
If I had to do it again, I would put the grid leak resistors on the power board, and attach the grid stoppers right to the socket pins without using turrets.
THAT might actually be a cool thing to try.
This board makes the amp very difficult to work on, and whoever has to replace a preamp socket is gonna want to pull my jersey up over my head and take a 5 minute major. :icon_biggrin:
Very nice. I like monster amps. What you say we take the baby and hit her will about 30db of boost for about an hour or so, just to hear it roar. :icon_biggrin:
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What you say we take the baby and hit her will about 30db of boost for about an hour or so, just to hear it roar. :icon_biggrin:
Geezz....As is, I can't even get the Master past 3 without crying for my mommy....last night I sat and dialed it around with the Master on 1 and I got some ringing today.
WE ARE OLD!, and this is a young man's (girl's) amp..
There is no need for any boost in front of this thing....if she says it doesn't have enough gain.....NO,,,,she wouldn't possibly :huh:
I am looking forward to trying a 10-band MXR EQ in the loop....I think that will make for a nice EQ'd solo boost when she needs to step out front, and fill in some of the mids she scoops out for heavy rhythm riffing.
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What you say we take the baby and hit her will about 30db of boost for about an hour or so, just to hear it roar. :icon_biggrin:
Geezz....As is, I can't even get the Master past 3 without crying for my mommy....last night I sat and dialed it around with the Master on 1 and I got some ringing today.
WE ARE OLD!, and this is a young man's (girl's) amp..
There is no need for any boost in front of this thing....if she says it doesn't have enough gain.....NO,,,,she wouldn't possibly :huh:
I am looking forward to trying a 10-band MXR EQ in the loop....I think that will make for a nice EQ'd solo boost when she needs to step out front, and fill in some of the mids she scoops out for heavy rhythm riffing.
I am speaking in terms of testing with the boost. See how well she holds together. I have a sort of kind of JCM 800 thingy with 4 of those el34. The one I mentioned having loads of plate voltage. I put a 18db in front and ran it wide open and she held on for about 5 minutes and started frying bacon and I had to let it cool a bit. Has all really high end stuff in the build.
Remember, I have an amp room so volume is no biggie I put off building one for years, but I have to say it is one of the best pieces of music gear I own.
I am interested in the overdrive. Did you get it mostly from a Bogner Ecstasy? I really like real Bogner amps. Everything about them. Just very versatile and do not really sound like anything else. First amp I ever heard that had a great clean that would get a great overdriven tone and everything in-between.
I guess everyone wants to make a good living, but I always hate to see using the Bogner name on a Line 6 amp. I like Line 6 products, don't get me wrong, but the 2 design ideas are worlds apart and sound like it too.
You mentioned a 5E3 for the clean. I do not really see it. What did you mean?
And lastly, don't you think it would be easy to put a tube reverb in the chassis? :l2:
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Hey, I've been following you build for a while, and the anticipation is killing me!!!! Need to hear how she sounds! :worthy1:
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1) I am speaking in terms of testing with the boost. See how well she holds together. I have a sort of kind of JCM 800 thingy with 4 of those el34. The one I mentioned having loads of plate voltage. I put a 18db in front and ran it wide open and she held on for about 5 minutes and started frying bacon and I had to let it cool a bit. Has all really high end stuff in the build.
2) I am interested in the overdrive. Did you get it mostly from a Bogner Ecstasy? I really like real Bogner amps. Everything about them. Just very versatile and do not really sound like anything else. First amp I ever heard that had a great clean that would get a great overdriven tone and everything in-between.
I guess everyone wants to make a good living, but I always hate to see using the Bogner name on a Line 6 amp. I like Line 6 products, don't get me wrong, but the 2 design ideas are worlds apart and sound like it too.
3) You mentioned a 5E3 for the clean. I do not really see it. What did you mean?
4) And lastly, don't you think it would be easy to put a tube reverb in the chassis? :l2:
1) I'm not quite there yet....although I never would of thought to run it that hard.
I would expect it to fail with that kind of abuse....and that's kinda why I was thinking of lowering voltages across the board.
2) Actually, my interest in Bogner came from one of his recent Line 6 products, that was labeled the Bogner Alchemist....
I took it into the iso. booth at GC and loved the overdrive....but after reading more about it, decided against buying it because of the problems that people were having with service, and I hated the idea of it being a joint venture with Line 6.
And that's what cemented in my brain the idea of wiring whatever I could find of his,,,,and that's where the Ecstacy experiments came from,,,and that's what eventually led me to this.
Before that, I had only heard his name and never was fortunate enough to plug into any of his products....
But,his overdrive is my overdrive. I'm not delusional enough to believe that I could do it any better....I just take his stuff and tweak it to my taste.
This amp is derived from what I learned from the Ecstacy experiments and what I gathered from a couple Ubershall schematics.....mostly Uberschall.
I just had to decipher them and strip them down to a useable form.
3) I just tacked the simple 5E3 clean on there as a simple clean channel, because I didn't have enough room for anything more,,,and why not include a proven winner? :wink: ....you'll see it on the schematic
I used the pot layout and tone cap connections from sluckeys Tweed on his website, and just added a master before the effects loop.
4) :l2:....yeah?,,and while I'm at it I could add some tremolo?...
I could just tack on a couple more terminal strips?,,,and maybe another chassis?,,,and mount the reverb tank on the back?... :angry:
Hey, I've been following you build for a while, and the anticipation is killing me!!!! Need to hear how she sounds! :worthy1:
Thanks Stank,,,,,It's tough to get a good sound with this much power....it's just crushing the input of my recorder :sad:
I'm getting there....
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One of the problems that I was having, was a poorly designed bias circuit....
I left myself a little short on available voltage and had to fix it before I could apply full input voltage...
Up until last night I was still only feeding it about 100VAC because I didn't have enough bias voltage at my disposal. I got it wrong the first time.
So I replaced the 10K bias pot (bad idea for this build), to a 25k pot and added a little resistance to ground (from 47K to 68K), and it gave me a much wider, usable range of adjustable voltage.
So I was able to apply full 120vac and that took the plates to 510VDC and the screens right to 500V (with the bias at 35mA), and played for a while.
The increased voltage brought out all of the growl in the EL34s and they held up for the limited amount of time that I was able to sit there and play.
I'm still thinking of putting a bucking xfmr in there, but I'll need a little more time with it to see how well different tubes respond.
And if you guys tell me those numbers are too high, then I'll listen.
I also still need to finish mounting the chassis and speakers in the cab and finish off a back panel with some labeling, warnings and instructions.
So there is still plenty to do....
I didn't mean to give the impression that it was finished....just that it is a working amp with no real major problems at this time.
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So I was able to apply full 120vac and that took the plates to 510VDC and the screens right to 500V (with the bias at 35mA), and played for a while.
The increased voltage brought out all of the growl in the EL34s and they held up for the limited amount of time that I was able to sit there and play.
Whoa?! And the tubes survived with 510V plate and 500V screen into 3.6k? I assume you have some screen grid resistors... Is the Eg2 of 500V measured before or after the resistor? I'd like to plot the loadlines to see what's happening...
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Hey jaz,,,welcome aboard....
I was just thinking about you because I forgot to mention your LED bias help...THANKS!
Whoa?! And the tubes survived with 510V plate and 500V screen into 3.6k? I assume you have some screen grid resistors... Is the Eg2 of 500V measured before or after the resistor? I'd like to plot the loadlines to see what's happening...
I tend to just throw round numbers out there to "ballpark" stuff so guys have an idea of where I am...I'll get a more accurate reading for you later, but those are pretty close.
I have 1K screen resistors and the 500V measurement I gave you was after the resistor,,, at idle
Thanks, as always, for your help and input!
I was also still considering putting in a dropping resistor in series with the choke, between the plate and screen nodes......?
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Hey jaz,,,welcome aboard....
I was just thinking about you because I forgot to mention your LED bias help...THANKS!
I tend to just throw round numbers out there to "ballpark" stuff so guys have an idea of where I am...I'll get a more accurate reading for you later, but those are pretty close.
I have 1K screen resistors and the 500V measurement I gave you was after the resistor,,, at idle
Thanks, as always, for your help and input!
I was also still considering putting in a dropping resistor in series with the choke, between the plate and screen nodes......?
Yeah, really late to the game, I thought you guys were talking about baseball... :icon_biggrin: Glad to see the LED bias worked for you. I was just reading Aiken's post way back on AX84 on the Marshall 100W load lines, and noted that someone mentioned that there was a lot of sag from idle to full power, as much as 100V on the plate and 125V on the screen! If you used the Marshall irons, then I would expect similar amount of sag, but still the tubes are under great stress - by design! It would be interesting to take some accurate readings while you still have it open on the bench, we know the idle voltages, now try slamming it and see how low the plate and screen can go, to see how the power supply's doing under full load. But I must say I am very afraid that something may be blown, so be very careful - crank it up slowly, and make sure the tubes do not redplate - they are already under great stress (I think).
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Yeah, really late to the game, I thought you guys were talking about baseball... :icon_biggrin: Glad to see the LED bias worked for you. I was just reading Aiken's post way back on AX84 on the Marshall 100W load lines, and noted that someone mentioned that there was a lot of sag from idle to full power, as much as 100V on the plate and 125V on the screen! If you used the Marshall irons, then I would expect similar amount of sag, but still the tubes are under great stress - by design! It would be interesting to take some accurate readings while you still have it open on the bench, we know the idle voltages, now try slamming it and see how low the plate and screen can go, to see how the power supply's doing under full load. But I must say I am very afraid that something may be blown, so be very careful - crank it up slowly, and make sure the tubes do not redplate - they are already under stress (I think).
Sounds good jaz...
It probably is time to give the speakers and my ears a rest and get some good old-fashioned scientific evidence going.
After 5 today I can get it plugged into a dummy load and give you some real time numbers.
Just for the record,,I used the 100 watt PT with a 50 watt'ish design (2-EL34), to purposefully avoid sag and leave plenty of power supply headroom.
Also for the record, while I had the input voltage down around 100VAC and had low 400s on the plates I went super hot with the bias (because I didn't leave myself enough -V in my initial design), and they held up @ 55mA each,, long enough for me confirm everything else was working OK
Other power supply accomodations include 2- 500uf / 500V (for 250uf / 1000V) first stage filter caps, followed by 2- 250uf / 500V (for 125uf / 1000V) screen node caps...
Sorry for the lack of schematic...I'm workin on it.
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I used the 100 watt PT with a 50 watt'ish design (2-EL34), to purposefully avoid sag and leave plenty of power supply headroom.
Other power supply accomodations include 2- 500uf / 500V (for 250uf / 1000V) first stage filter caps, followed by 2- 250uf / 500V (for 125uf / 1000V) screen node caps...
That's why you have 510dcv on the plates and 500dcv on the screens.
Only half the expected load on the PT and (way) oversized B+ filter caps at the 1st node (plate) and 2nd node (screen).
Brad
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That's why you have 510dcv on the plates and 500dcv on the screens.
Only half the expected load on the PT and (way) oversized B+ filter caps at the 1st node (plate) and 2nd node (screen).
Yup,,,no surprise. :icon_biggrin:
I was curious how it was gonna look under load,,,and I'm Ok with that,,for now
On the bench PS I was feeding the bridge 350VAC, and coming out in the high 490's......and there's no sag in my bench PS either
Part of the "metal" designs include very stiff power supplies and oversized caps...as well as stressed out power tubes at stupid-high voltages.
That's why I'm here....cause I've got you guys to bring me back into an acceptable range of stupid-high :l2:
So far, my only guideline for a max rating is a glowing red bottle...which I haven't seen, YET
Once I post something,,,please don't keep the sound clips on my permanent record,,,,,it's just me doing an impression of me, if I were a metal-head :wink:
Any true metal guitarist would call me a poser and toss my work in a pile with the Hansen twins.. :laugh:
I'm real curious to see jazbo's load lines....
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So far, my only guideline for a max rating is a glowing red bottle...which I haven't seen, YET
There's a little more to it then just red plating.
Speaking overall the higher the B+ plate (and screen) dcv the less current you can run through a tube.
But when you get up to the limits of a tubes B+dcv you can have ark over/internal shorts between the different elements inside the tube.
This can/will probably happen/be more risky with new production tubes as they don't seem to be as robust overall as opposed to tube golden years production.
The internal materials seem to have been stronger in the old tubes and were aliened better? They also seemed to stay in alignment better with hard use and rougher handling? Heat weakens metal.
Not a guarantee you will have an internal short but I think the risk is greater.
Brad :think1:
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So far, my only guideline for a max rating is a glowing red bottle...which I haven't seen, YET
There's a little more to it then just red plating.
Speaking overall the higher the B+ plate (and screen) dcv the less current you can run through a tube.
But when you get up to the limits of a tubes B+dcv you can have ark over/internal shorts between the different elements inside the tube.
This can/will probably happen/be more risky with new production tubes as they don't seem to be as robust overall as opposed to tube golden years production.
The internal materials seem to have been stronger in the old tubes and were aliened better? They also seemed to stay in alignment better with hard use and rougher handling? Heat weakens metal.
Not a guarantee you will have an internal short but I think the risk is greater.
I do get the power ramifications (higher voltage, less current)....it's the only part of this audio stuff that crosses over into my day job, so it's been a little easier to assimilate :think1:
And with this design, less current is gonna be OK.. BUT, it comes with the adverse effect of raising the B+ voltage slightly
I'm skating just over the line of the published screen voltage spec of 500VDC......some types post 450VDC as max.
So, in this case,,,assuming I'm stuck with new production tubes into the future, I'll mark you down as a proponent of dropping B+ :icon_biggrin:
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Be afraid, very afraid... Here are two charts for you to consider: left - load line at idle, right - load line assuming 100V sag on the plate and the screen grid voltages. As scrary as these charts look, they are actually very similar to the Marshall 100W load lines that Aiken did, may be that's part of the magic with these amps?! If you have an even stiffer supply than the Marshall, then the situation is even worse, I am not sure how long the EL34s can last under such condition.
Note the Po of 109W shown on the left chart is for the ideal condition, with zero supply sag at full output, clearly that it can not be achieved with the tubes (they will melt) or the OPT (it will be cooked). And the right chart shows if the supply sags, then the amplifier is essentially operating in pure Class B!
(https://dl.dropboxusercontent.com/u/1326040/EL34_PP_500V_3.6k.gif)
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Thanks jaz,
I'm not sure that you picked up on the fact that I'm only running 2 - EL34 into that load...?
It looks like those curves are for 4 tubes at 109 watts output??
OK, I've read your post 10 times and stared at those charts and read some of what Aiken wrote..... :huh:
How are hundreds of thousands of JCM800s running perfectly fine for 30 years and not eating tubes like french fries?
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OK jaz,
Here's some real world numbers for you...
I can't believe my eyes :huh:
I dropped my supply voltage back to 110VAC just to cool things down a bit and wound up with 464V plates and 460V screens
I've got 1 meter hooked up to the OT CT and another meter hooked up to one side EL34 screen
I also dropped the idle bias current to 20mA just to help(?)...
I applied a 1K signal and pushed the Master volume to about 1/2 (probably about 70% of full), with an 8ohm dummy load on the 8 ohm tap
The plates dropped to 438V
The screens dropped to 422V
Here's the crazy part that coincides with what Aiken was talking about...
One side jumped to 106mA :huh: and the other side jumped to 58mA
That's 44 watts dissipation on one side and 24 on the other!!
No red plating after 5 minutes :w2: :dontknow:
I switched the tubes and the jump was evened out (a little better) to:
71mA on the side that was 106
55mA on the side that was 58
So it sounds like one of the tubes just takes the beating better :huh: :dontknow:
And I had the mids scooped out (which includes most of that 1K signal).....when I brought that into the mix it was like a flame-thrower and I was seeing plate currents up near 150mA (for a split second, before I turned it right back down)
I'm gonna try a couple different loads and record those numbers, just to see what we can learn.
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Changed to a 5ohm load and got:
96mA on the side that was 71 (we'll call it side A)
66mA on the side that was 55 (we'll call it side B)
Changed to a 24ohm load and got:
57mA on side A
37mA on side B
And with the 24 ohm load it took a lot more signal input to get the same sag result
I just needed to do that to visually confirm theory, and to catch up with the idea of needing to increase my primary impedance for this application...
Or just mismatch in the right direction, and mark the speaker out for the adjusted impedance....
Just to sleep at night knowing that I'm not melting any innocent ELs....
I am not concerned with max output,,,but I am concerned with max. reliability
During all of my testing I did not see red plating for 1 second. :huh: :dontknow:
Thanks again for all of your help jaz!....thought provoking and steering me in a better direction!
:thumbsup:
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So it turns out that I prefer the sound of an EL34 being pushed towards meltdown....
Guess I'm not the first.
:icon_biggrin:
I plugged a 16 ohm cab into the 8ohm tap and lots of that great crispy, crunchy, sizzling zip was gone....
So now what?....be "nicer" to the EL34s?
What was that Jim said about KT88s? :angel
If I switched to a bigger tube I'd have to change the OT to handle it.....ehhh :BangHead:
Back to the bench...
I know what you're thinking...isn't this what the breadboard is for? :angry:
Please don't say it... :icon_biggrin:
I assumed that because there were millions of amps slowly destroying EL34s out there, that this was an OK idea........
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So I went back out, and just acted like I didn't know anything about numbers, or loadlines, or jazbo, or dissipation....
And nothing traumatic happened...
No fuses blew, no tubes got red, no one died......
8 ohm speaker load into the 8 ohm tap with 110VAC input and 460 V plates
And even though I was monitoring over 100mA of cathode current while I was playing at approx. 40% output, it didn't stop me from getting some stuff recorded...
So I will edit that down and at least you'll get to hear how it sounds now before I chicken out and do something safe to delay the onset of the inevitable disaster.
:icon_biggrin:
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Oh,,, and here's the preamp schematic....
I'm hoping there are no errors, and I will continue to look it over as I finish up Page 2
The amp's name is the AK47,,, as it was partially derived from it's humble beginnings as the bastard child of a once innocent Sovtek Mig 50,,,
it's ability to mow down anything in it's way,,,and part of a joke that I can't tell...
I apologize in advance for anyone who may be offended by the use of the name of a soviet military weapon,,,,,but please remember this is only the name of an amp, and the cold war has been over for 30 years.
I honestly don't mean any dis-respect to any military personnel, and I truly hope none is taken.
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> That's 44 watts dissipation
No.
The rise in current from 20mA to 106mA goes along with pushing *power* into the *load*.
Much of the voltage and current in-to the tube passes through to the load.
How much? You need to measure the power OUT. You also want to monitor it, see if it is nearly maxed-out or clipping absurdly. (Which means you need a tone generator, not an axe.)
The 106/58mA suggests that one of the tubes (or driver) is sick, you are far past clipping (most amps do not clip symmetrically), or you are using an asymetric signal (which adds confusion).
Plate currents in a "50W" should be larger than ~~60mA. The Philips 1969 sheet shows 2*120mA for 55 Watts out at 425V supply (400V at anodes) and 3.4K load.
http://www.mif.pg.gda.pl/homepages/frank/sheets/010/e/EL34.pdf (http://www.mif.pg.gda.pl/homepages/frank/sheets/010/e/EL34.pdf)
Assume Philips knew something. 400V*(2*120mA) is 96 Watts IN-to the amplifier. They saw 55 Watts out of the amplifier. The difference, 41 Watts, is lost in the tubes, mostly in the plates. Two tubes, so at full power we have 20.5 Watts dissipation per plate.
The maximum dissipation is usually at part-power, often near half power. (This is why serious audiophiles objected to the FTC's 1/3rd-power test... it is nearly worst-case, will never be approached in "clean music".)
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Thank you very much for keeping an eye on me PRR.
Your words are comforting at the least....I knew there had to be a sensible explanation and I knew I couldn't possibly be right. I was gonna have trouble sleeping tonight without your explanation.
Of everything that I have learned, this is obviously my weak spot.
The 106/58mA suggests that one of the tubes (or driver) is sick, you are far past clipping (most amps do not clip symmetrically), or you are using an asymetric signal (which adds confusion).
I think it's a combination of a sick tube,, dealing with a square wave...
This was my test pair, and when I swapped in a fresh set I saw more even results, even though I didn't record any.
Your supervision is priceless and gives me the confidence to move forward after being paralyzed by my own ignorance.
THANK YOU,,,AGAIN!
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I see you have been busy... Based on the new voltage readings, here are the load lines for the 8 Ohms & 24 Ohms loads for your consieration. I also had a question, when you said the plate jumped to 100mA, was that the reading across the cathode resistor? Ditto for the 20mA? I think if you are less interested in getting the maximum output power like Marshall, and prefer reliability, then you need to re-configure the output stage's operating condition (see bottom chart), unless of course, by doing so, it ruins "the tone"... Also, BTW, Aiken mentioned that certain models of the Marshall 100W amps were well known tube eaters, so I would not bet on the EL34's longevity, especially not with the current production tubes.
(https://dl.dropboxusercontent.com/u/1326040/EL34_PP_420V_2loads.gif)
A very conservative scenario:
(https://dl.dropboxusercontent.com/u/1326040/EL34_PP_350V_7.2k.gif)
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Based on the new voltage readings, here are the load lines for the 8 Ohms & 24 Ohms loads for your consieration. I also had a question, when you said the plate jumped to 100mA, was that the reading across the cathode resistor? Ditto for the 20mA?
Thanks for taking the time to do that...I was very curious how to how they would look..
And, yes,, I was taking the current readings across the 1ohm cathode resistor,,, only.
So in your very conservative example, I see RL=7.2K which makes it easy for me to get there by just doubling the load on the secondary...
What does the line look like if I just stay at 460V plates, but use a 8 ohm load on the 4 ohm tap to reflect 7.2K on the primary?
I think if you are less interested in getting the maximum output power like Marshall, and prefer reliability, then you need to re-configure the output stage's operating condition (see bottom chart), unless of course, by doing so, it ruins "the tone"...
There's one thing I need to change about what I said last night....
When I plugged the 16ohm speaker cab into the 8ohm tap I reported that some of the "tone" had been lost,,,but I had accidently switched to my rhythm (neck single coil) pickup and didn't know it,,,, I didn't notice until I plugged in a new set of tubes and was trying to figure out where the tone had gone...
So I was mis-judging the resulting tone of the impedance mis-match with the wrong pickup selection......
I will try that again tonight, and try to give more accurate, subjective reports of TONE
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So in your very conservative example, I see RL=7.2K which makes it easy for me to get there by just doubling the load on the secondary...
What does the line look like if I just stay at 460V plates, but use a 8 ohm load on the 4 ohm tap to reflect 7.2K on the primary?
You got it, 8 Ohms on the 4 Ohms tap or 16 Ohms on the 8 Ohms tap will give you the 7.2k primary load. The chart would look the same.
I didn't notice until I plugged in a new set of tubes and was trying to figure out where the tone had gone...
So I was mis-judging the resulting tone of the impedance mis-match with the wrong pickup selection......
I will try that again tonight, and try to give more accurate, subjective reports of TONE
Cool, let's see if the tone is still acceptable with the higher load.
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Cool, let's see if the tone is still acceptable with the higher load.
Jaz,
I was hoping to have a good solid answer for you , but I don't...
Part of the problem is that when I switch to the 16 ohm load it is a Marshall bottom cab (loaner) that has 4 G12T-75's, and I don't like the way it sounds any other time anyway.....so it does change the tone and it clouds my results (which are mostly my subjective opinion anyway)
Sooo,,,I did notice a change in tone that was not desirable with the higher load.....maybe thinner and with less "zip"
And since I liked it so much the other way...I decided to install the bucking xfmr and be done with it....plate V is down in the 460's now (depending on bias) and it just sounds phenomenal, so I'm done F'in with it.. for right now.
I've got to get the cosmetics in order. :sad:
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The girl wanted to hear her amp, so I put a big push on this past Sat. and took it in to her....
Here's a couple pics of the amp, with it's temporary 'prototype' graphics,,,which I'm sure you guys will get a kick out of.
It felt strange to take it out of my shop, and it made me a little nervous to realize that I wasn't going to be able to travel with it. :wink:
It received the highest of marks from her and her co-workers, and she absolutely loved the sound,,,and thinks she might want another one :huh: :BangHead:....the coolest thing she said was:
"It sounds better than the Blackstar or the Marshall DSL I was looking at" :happy1:
That was all I needed to know.
The grill cloth was tight when I installed it, and I'm pretty sure that the wind coming off the speakers is what stretched it out and made it saggy... :huh:
After the big push, I took the week off, because the due date has been moved back to late July,,,and I just had to get away from it for a couple days.
Here's a link to a short clip of the amp with the gain maxxed out and a couple slightly different tone settings, including the mid-scooped "metal" tone...
The clip is just to demonstrate the brutality of the available gain,,,,but I found some better settings with the input gain rolled back.
Excuse #2---the sound quality is poor due to the fact that I can't get the recorder too close to it without overloading the input....it is what it is:
http://www.soundclick.com/player/single_player.cfm?songid=12806552&q=hi (http://www.soundclick.com/player/single_player.cfm?songid=12806552&q=hi)
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THAT is AWESONE! You should be super proud of this beast! Once the word gets out, you will be busy for months - years! It would be cool to get a recording of her using it in a live setting - to see how it cuts through the mix. I'm sure it will do fine! Well done, well done indeed!
Jim
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THAT is AWESONE! You should be super proud of this beast! Once the word gets out, you will be busy for months - years! It would be cool to get a recording of her using it in a live setting - to see how it cuts through the mix. I'm sure it will do fine! Well done, well done indeed!
THANKS MAN!
That's the most POSITIVE thing you've ever said to me so I had to quote it just in case you edit it out,,,it will live forever with this thread :l2:
:occasion14:
I was thinking of doing it in a head format, right now, while it's all still fresh in my head....any more reviews like that and I'm gonna have'ta...
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Well it looks great and I'll take your word that it sounds great too.
Well Done!
Brad :bravo1:
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I'll take your word that it sounds great too.
Now THAT's funny :l2:
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I'm sorry that didn't come out right. :BangHead:
I know it sounds great!
Brad :w2:
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Top marks SG, Keep up the good work. AWSOME
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Top marks SG, Keep up the good work. AWSOME
Thanks TIMBO!
I'm gonna work on a better clip, because I really don't think this does it justice....I just had to put something up so I didn't keep you guys waiting
In person it's just brutal and has a great, tight, controllable feel.....it sounds incredible with EMG's
The clip is with the gain all the way up, just to demonstrate the far end....at 3-5 it's not such a bee-hive :icon_biggrin:
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Man, it's really got the in-your-face attitude down, well suited for the type of music she is playing, so that's what counts. As for the higher load not sounding as good, I am not surprised, as that's part of the Marshall tone - the pretty load line doesn't mean a thing if it sounds bad :icon_biggrin: Great work, looking forward to hear more clips of the beast with improved recording...
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That is killer SG, and molded after the greatest metal amps combined. So many great metal guitarists out there I can only imagine how many amps you looked at. If you can go from Micheal Schenker to Dimebag in one amp I'm sold :icon_biggrin:
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That sounds really impressive! Congrats, I think its a winner!
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That really turned out great. Good looks and good sound. And we know who she'll be calling on when she needs a tune-up. :wink:
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Gotta love an amp that just reaches out and grabs ya. :guitar1
Bill
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Well thanks again guys, I really appreciate all of the positive comments....it appears that my week off is turning into a week and a half. :icon_biggrin:
There's still plenty to do and I'm looking forward to getting back to it and cleaning up a couple things, including a new back panel and faceplate, re-stretching the grill cloth, and some slight troubleshooting.
I'm also considering taking it into a local studio to get a real demo....it deserves it.
I'm still working on page 2 of the schematic, and I already have one slight revision to make on page 1.
Here's a pic I snapped when we were in the isolation booth trying it out....I covered her face for her privacy, but you get the idea...
She's giving us the universal metal sign for "IT ROCKS!"
And we know who she'll be calling on when she needs a tune-up. :wink:
The scary part is she's moving away and taking it with her,,,,,so I'm gonna add one of those 'message in a bottle' type care packages that TIMBO brought up recently including contact info. for me, a schematic, and explanation of the design.
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Gotta love an amp that just reaches out and grabs ya. :guitar1
Bill
I knew you'd appreciate this one TJ.
It's got this great low end growl to it that I can't get enough of.
It would be cool to get a recording of her using it in a live setting - to see how it cuts through the mix.
Unfortunately, that's not gonna happen.....
But, funny thing is,,,I don't think she really wants it to cut through....she's a solid rhythm guitarist and she wanted me to build it purposefully less bright than the Sovtek (which she tried)
When we were demo'ing it, I kept turning up the treble, and she kept turning it back down.....
Maybe that's got something to do with me losing some of my high freq. hearing? :icon_biggrin:
Her request was more gain and more bass.........she got it.
It would be very easy to bring back some highs with just a few small changes to the schematic.
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That really turned out great. Good looks and good sound. And we know who she'll be calling on when she needs a tune-up. :wink:
Okay, so what about when the amp needs a tune up? :wink:
On a serious note, its a shame she's moving away and you won't get to hear it in person. I would love to build someone an amp and hear it used as intended, not just my hack playing!
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That thing rocks. Why didn't you do a demo of the high gain channel? :l2:
Great job, really. You know everyone likes different things, but in the high gain territory this thing is really nice. Love the way you can still hear all the notes in the chords and the squeaks and grunts.
Did it end up being fairly quiet when idle?
Maybe a studio recording would do justice, but what an amp sounds like live is much different than a studio produces. The demo is great and I can tell what it sounds like.
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That thing rocks. Why didn't you do a demo of the high gain channel? :l2:
:l2:
You know ME :icon_biggrin:.....there is still more to showcase, but I had to get a way from it for a while...you know how that is
Great job, really. You know everyone likes different things, but in the high gain territory this thing is really nice. Love the way you can still hear all the notes in the chords and the squeaks and grunts.
I think so too....I think it's a great type of super-high gain style that guys don't usually build, because the market covers most of the bases...
I was hoping that the clarity would come through a little better...
One improvement was subbing in a 12AT7 in the PI in place of the 12AX7 I initially had in there....it brought out definition and clarity and got rid of some buzz....was a keeper, and I used a JAN Phillips NOS there
Did it end up being fairly quiet when idle?
Yes, and that was one of my biggest concerns with stuffing this all in there....I want to believe that the separate power supply and separate power board had something to do with it,,,,but my buddy that helps me with play testing/tweaking was very surprised with the low noise...it does hum/hiss, but nowhere near what it could if it was poorly made...
Maybe a studio recording would do justice, but what an amp sounds like live is much different than a studio produces. The demo is great and I can tell what it sounds like.
Yeah,,,I was just hoping that they would have some better equipment that would be capable of harnessing the power...I have the input vol. on my little field recorder on 7 (out of 100) and it still clips...I don't like the demo clip, but it's all I've got so far.
But you're one of the guys that I was worried about,,,so if you say it's good, then it's good. :thumbsup:
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So what are we?!?!?! Chopped liver?
Wow.....that is positively the last time I am positive about anything remotely positive that may surround your negatively biased aura - and I am positive about that... :lipsrsealed:
Thanks a lot ex-pal... :m13
Jim
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But you're one of the guys that I was worried about,,,so if you say it's good, then it's good.
So what are we?!?!?! Chopped liver?
Don't be so sensitive....there's no place for that here...this isn't the Oprah Forum!
Who's to say you weren't on the list?
I'm pretty sure Ed can hear the difference between 2 gnat farts at 100 yards ....that's what makes his opinion matter to me....if he would have PM'd me and said "Yo man, that sounds like crap,,,what are you smokin' up there?",,,I would've tried again. If you would've said it, it would've been Jim being Jim.
Me and you suffer form the same 1K ringing that makes us not be able to differentiate between a plane flying overhead and someone flushing a toilet upstairs.....so when you say it's good, it's no different than being told that the sound of a train coming to a screeching halt is pleasant.
Get over yourself!.....sheeesh :rolleyes:
Thanks a lot ex-pal...
Well that was not surprisingly,, short-lived
And you have earned yourself a new nickname : CL (Chopped Liver)
Which is, again, not-surprisingly,, the opposite of LC.
So as kind, caring, considerate, funny, talented, handsome, intelligent, honest, and just an all around great guy that I am....(I know this because it says so on my birthday cards every year)
You sir, are the opposite.
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Hey, I've heard some very melodic screeching train stops - so there!
As far as the toilets flushing, plane overhead, 1K ringing.... Are you talking about a Tele?
What ARE you smoken up there? Hey, I'm still trying to be positive here!
CL :m8
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Great to watch the build progress. Also very cool to see the input/interest from the very learned seasoned builders to the newly interested. With all of the different trades that are here has anyone come up with anything like using pipe conduit and stuff like that. My first build was a take on that because I saw so many Supros-those split chassis little hot rod jobs.
This build of yours mirrors very closely what I would like to have as my next project. I'm a big fan of the tone only knob. Being a big fan of pedals, having a boss heavy metal pedal with the concentric knobs, the odd 1,2,3 tube screamer all set differently, od of choice...fuzz...all flavors of gain would be there.
But gigging, and pedals are growing tiresome-not the playing, but hauling my own rig. Hauling a small amp, with all the gain I'd ever need and being able to turn up or down from just my volume on my guitar is becoming extremely attractive.
All my friends are from N.Y. and Rangers are spoken...especially Hendrick Lundquist if you're talking to my girl Jeanette.
This move has been really tiresome, and having all my stuff from the shop all boxed up- some in the old storage some in new storage and some at the new place is almost de-moralizing...but its a ray of light to live my amp building life vicariously through yours. Keep it up...The Gain, that is.
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