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previous: Joseph Futral This is my first foray into an amp ... -- 10/10/2000 6:59 PM View Thread

Re: Looking for feedback

10/10/2000 9:52 PM
Scott Swartz
Re: Looking for feedback
"1. The plate voltage at the PI tube seem kind of high. Since I am looking for more overdrive sound, should I try to lower these? How?"
The split load phase inverter you are using should drop 25-30% of B+ across each resistor (47K on your schem). Try increasing them to maybe 68K for a higher drive voltage.  
"2. I've never tried to work out a fixed bias amp, everything else I have built have been cathode bias. This amps bias circuit seems just a tad different from what I have sen on other schematics. Any thoughts?"
Looks pretty standard to me, but the cap should be rated 100VDC.  
"3.The power filter caps' values seem small when compared to some Fender or Marshall amps. What difference does this make?"
More capacitance gives a little tigher bass, I prefer about the range shown on your schem  
"4. The power tubes are Svetlana 6L6GC so they can handle the voltages, but do I really want them this high with what I am looking for out of this amp? Is the only way to affect this significantly to change the power tranformer?"
Lower B+ will distort easier if thats what you are looking for.  
For a Full wave rectifier you can put a 50W zener in the CT lead and drop some voltage, not sure if you can do this with a bridge, I'd have to think about it, or maybe someone else knows how.  
You are running the SV6L6GCs at 23 watts dissipation, which may be a little hot.  
[QUOTE]5.Any other thoughts? Feel free to email me  
directly if you prefer[/QUOTE]  
If you want more distortion, you could cascade the preamp stages, use master volume, switch stages in and out, and use a DPDT to switch between the two tone stacks for the Fender/Marshall EQ changes, etc.  
Or maybe this  
Gain(first stage from Fender preamp)  
Cathode follower+Tone Stack  
A switch or relay would select the Fener or Marshall path  
Check out Boogie or late Marshall schems, you'll see similar approaches