Just curious - does the PP/SE control go all the way to SE, i. e. can it completely remove the drive from one tube? I would love to try this on an amp, but everything I've got right now is class AB, and the bulid/mod fund balance right now is pretty close to $0
The SE/PP control is basically shunting signal from one tube to ground and is pretty simple to implement. It involves 3 resistors, one pot, and some wire. We've talked about it here before and over on the 18watt.com. Look at the Vajra schematic in the downloads section on 18watt.
With only one tube receiving signal, you are effectively running in single ended mode. This would Class AB SE, which is where most SE guitar amps run.
OK. Thanks for your reply. Sounds like implementation of this is much as I imagined it, but for whatever reason I assumed that it would sound like poo unless the SE tube was biased hot enough to run class A.
My education in electronics left out two very important facets relative to amp construction - tubes and tone. I caught up on tubes on my own, but I'm still trying to figure out what good tone looks like on paper. This is something I'll definately try, as soon as there are a few cents in the above-mentioned budget.
