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Trainwreck...built one...a ton of gain 2B expected???


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9/25/2000 2:38 PM
Trace
Trainwreck...built one...a ton of gain 2B expected???
I'm sure I'm in the minority here and I'll get a ton of flack for this (to be expected)...  
 
I tried the TrainWreck circuit and as much as I hate to say this (keep in mind I have a great amount of respect for Ken) but I'm really not sure why people would spend in and around $5K for this tone(?) Am I the only one who feels this way??? I know tone is in the eye (or ear) of the player...perhapes I expected something different! (ha, ha)  
 
The lack of the grid stopper/input resistor (typically 68K) seems to be a source of what makes the amp "loose" and "gainy-grainy-slushy." Even with a 33K in this spot the amp sounds better but still very "gainy."  
 
If I had to compare this to another type of design I would say it sounds similar in tone when you lift the tone stack from ground on a Fender amp. It's pretty darn similar in tone (odd I know).  
 
I tried a "Matchless" Master volume (ala-spitfire) and the preamp just mushes up really quickly, so much so that I was shocked.  
 
Now I know that this amp is NOT a Master Volume design however people will crank the little devil up and you'll still end up with the same thing but when the EL34's (or whatever) start to break up it will be even worse.  
 
Has anyone else run into this??? I really wanted to like this circuit because of all the talk and I do respect Ken very much. I think the .001 (I believe) coupling cap works well with low plate voltages but it could be bumped to arond a .02 if there's more than 450V on the plates (I should say that's my opinion!! ha,ha)  
 
Now I'm NOT trying to stir up a flame war here!!! (ha, ha) I'm looking for other people's experiences to see if I'm way off base here, well you get the idea....just keep the gasoline way from the matches!!! :)  
 
Trace
 
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9/25/2000 9:24 PM
Joe L

quote:
"The lack of the grid stopper/input resistor (typically 68K) seems to be a source of what makes the amp "loose" and "gainy-grainy-slushy." "
 
 
Maybe we are using different guitars or different volume levels but that just doesn't describe what mine sounds like. I am using a .0047/150K after the second stage and mine gets very plexi sounding with the guitar (Strat with Rock Van Zandts) on 10 and the amp on 4. The parts I chose were for the highest definition with smoothness in the high end and I am using Seimens EL34s for the outputs. My HV is 422v on the EL34s and the preamp tubes are OS RCAs. I tried a 5 * GE 5751 in the front end and that was even better for the clean sound but a bit dark when cranked.  
 
To describe mine I would have to say spanky sweet high end with dynamics that can hurt you when clean morphing into Plexi brown when pushed with lots of tendency to feedback. It definately distorts from back to front.  
 
I'd say keep playing with it. Component selection is ULTRA important with this amp. Much more than anything I've ever played with.  
 
..Joe L
 
9/26/2000 12:49 AM
Mitch

Joe,  
Did you do the wreck that was the one that said very early EVH sounding?
 
9/26/2000 1:18 AM
Joe L

No. Mine is somewhere between A1 and A4. The EVH sounding one looked too bright for me. And of course me being not so bright, it wouldn't have been a good match :-)  
 
..Joe L
 
9/26/2000 6:50 AM
BWilliamson

quote:
"really not sure why people would spend in and around $5K for this tone(?) Am I the only one who feels this way???"
 
 
kinda have to agree with you here--I wasn't as impressed as I thought I should have been. The gain was over the top, but I couldn't coax much of a clean thru this amp.  
 
Now, the original schem was supposidily based on the Callaham clone, reading Mook's West Coast Amp-Shootout. The description of that amp is it's just a gain machine.  
 
So I'm guessing we're missing something. According to Holger(if I'm remembering correctly) when he showed the schem to KF, we were really close--but not quite. I personally think that's what we are missing.  
 
When preparing my clone up, thinking about your tweaks for Marshall's--mainly the MV. I thought playing with the 3rd stage cathode resistor might help control some of the gain. It does seem to tame the beast a bit, I don't think it sounds as good as it should.  
 
Thinking of going after the feedback resistor next to see what that does. But I keep reading how KF amps are staged so that the power amp clips right before the preamp, and that's where tha magic lies. Seem to get way too much signal from the preamp for that to be happening. Going under the next assumption that with all that signal coming from the preamp--the driver's being overloaded. Since we're not quite sure which tap or even if that 100K FB resistor is right, to me seems to be the next experimentation opportunity.  
 
quote:
"I think the .001 (I believe) coupling cap works well with low plate voltages but it could be bumped to arond a .02 if there's more than 450V on the plates"
 
 
I've posted about this ad-nauseam. But I don't like the .001 personally.  
 
But I agree with your gain assement. I currently running a 5751 for the first two stages, and a 12au7 for the third. Sounds really great, but still don't have quite the clean when backing off the guitar I really am looking for.  
 
bw
 
9/26/2000 6:52 AM
BWilliamson

I should add, I've never played a more harmonically rich or amp that reacts like this one to what your hands are doing. I really believe there is lots of mojo in this circuit when dialed just right.  
 
bw
 
9/26/2000 2:10 PM
Trace

quote:
"kinda have to agree with you here--I wasn't as impressed as I thought I should have been. The gain was over the top, but I couldn't coax much of a clean thru this amp."
 
 
That's pretty much what I've found as well. I do not hear this amp as having a "plexi" tone to it at all. I've tried all the versions (small changes in all teh versions) but it's still pretty much the same animal, which isn't a bad thing is someone wants that tone :)  
 
quote:
"Now, the original schem was supposidily based on the Callaham clone, reading Mook's West Coast Amp-Shootout. The description of that amp is it's just a gain machine."
 
 
This makes sense. If the volume is on 2 you are pretty much in the clean area (depending on the pots taper) but after that it's mighty gainy and hard to control at high volume settings.  
 
quote:
"So I'm guessing we're missing something. According to Holger(if I'm remembering correctly) when he showed the schem to KF, we were really close--but not quite. I personally think that's what we are missing."
 
 
Yeh, there's something missing (in my humble opinion) hard to describe but it doesn't sound like $5K as ar as the tone goes. It's strange and hard to put your finger on.  
 
 
quote:
"When preparing my clone up, thinking about your tweaks for Marshall's--mainly the MV. I thought playing with the 3rd stage cathode resistor might help control some of the gain. It does seem to tame the beast a bit, I don't think it sounds as good as it should."
 
 
I've played with that as well and I agree. Components are critial and I think the plate voltage will largely determine the coupling cap values (which would explain the top-end issue).  
 
 
quote:
"Thinking of going after the feedback resistor next to see what that does."
 
 
It doesn't alter the amp all that much, I should say it's not the cure to what you are looking for (ha, ha).  
 
quote:
"But I keep reading how KF amps are staged so that the power amp clips right before the preamp, and that's where tha magic lies."
 
 
I agree. The preamp is breaking up wayyy before the power amp is. With the preamp breaking up this much, then you crank the amp to get the EL34's breaking up you are pretty much left with mud (again, in my humble opinion).  
 
I've got three Les Paul Customs, 1970 Gold Top and an older Strat so it's not the guitars causing the problem. I have a gut feeling that something is missing in the schematic and it could be something very simple since this circuit is very sensitive to changes.  
 
quote:
"Seem to get way too much signal from the preamp for that to be happening."
 
 
Yep, I agree there!  
 
quote:
"Going under the next assumption that with all that signal coming from the preamp--the driver's being overloaded. Since we're not quite sure which tap or even if that 100K FB resistor is right, to me seems to be the next experimentation opportunity."
 
 
I can see your logic there but I've played with that heavily and it's not the answer in my opinion. Ken is a pretty big lover of the AC30 and the schemtic for the Trainwreck looks very similar (topology) to a bassman (not exact of course).  
 
quote:
"I've posted about this ad-nauseam. But I don't like the .001 personally."
 
 
I agree there... if the plate voltage is around low 300's then it makes sense.  
 
Trace
 

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