previous: BWilliamson q{really not sure why people would ... -- 9/26/2000 6:50 AM

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

9/26/2000 2:10 PM

Trace

Re: Trainwreck...built one...a ton of gain 2B expected??? 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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BWilliamson q{It doesn't alter the amp all that... -- 9/27/2000 1:57 AM