High-gain rat's nest

[92Volts]

In time for halloween, a build to make everybody cringe 

Preamp is the Lead 2 by Brian Schmittling, John Hynes and MasonAtom at AX84. Poweramp is a normal SE with a Champ transformer. I got the PT off eBay and it limits me to 6V6ish bias current but a 6L6 sounds and looks good! I've got 385v on the output plate and 310v on the screen, similar for the preamp.

This chassis was a lot smaller than I expected! There's probably a lesson to be learned here about drawing layouts beforehand... that and using turret board.

The amp might be the quietest high gain amp I've played. One advantage of this construction method is all parts are near where they're needed and leads are short. Until something goes wrong or the builder loses his mind working on it!

This will undergo revision to tidy it up but I'm thrilled with how it sounds. Plenty of gain for heavy metal stuff-- and a lot of lower-gain sounds too. It can get fully clean, but not as well as I'd hoped. If I had more gain after the tonestack (like a PP stage with phase inverter) cleans would likely be loud enough to fully drive the output. It gets loud enough for practice now but doesn't fully drive the output while clean.

[davidwpack]

Not too shabby. Nice. I'd throw in a 12AY7 or two and see what happens.
I like the pilot light on the top too.

[92Volts]

Not too shabby. Nice. I'd throw in a 12AY7 or two and see what happens.
I like the pilot light on the top too.

Thanks!

And I might try that. I've tried a 12AX7 in place of one of the 12AU7s and it was noisier and "buzzier" though the later tube's gain is limited by their cathode resistors to the extent that gain wasn't affected that much.

Any reason you suggest a 12AY7 in particular? For another build I'm considering getting a 12AT7 for phase inverter use, though I'm sure either could work for either purpose.

[SILVERGUN]

That is daring in a high gain'er, but just goes to show how a good circuit just wants to work.
I have adopted this same technique of wiring the circuit close to it's intended path and I do believe that has a lot to do with your success. At one point I did a DR Champ by just sitting there with just a schematic, parts and some light logic and it came out just fine. It was very fun because I didn't spend a month planning, just sat down on a Fri. and had an amp by Mon.
 
Kudos to you for being brave enough to try it and congratulations on the success.
Would enjoy seeing the schematic if you get time.
Cab looks nice, did you make it?

[92Volts]

I haven't yet put the schematic together for the whole thing, but the important part (the preamp) is VERY similar to the default version (including the unusual tonestack) here: http://www.ax84.com/lead2.html

1M master volume pot, then the power amp is as simple as it gets. Biasing is a 520ish ohm resistor combo in series with a 200 ohm pot and 1 ohm for measuring.

Power supply is somewhat insane because I'm using the 570v CT winding for the output and 220v winding for the screen and preamp, I'll probably do a schematic for my own reference but somebody else building a similar amp would do it differently.

I did make the cab! With a lot of help from someone knowledgeable, while using their tools :)

[davidwpack]

Oh, I assumed being high gain they were 12AX7. Disregard my 12AY7 suggestion.