Plate voltage is too low on output valves.

[6267]

I've got 6ma on each screen (or 5 on 1 and 1 on the other, shared screen R), they're not 6v6s, but damn close construction wise. 10ma isn't unacceptable though, it's just a bit high. The screen has a lot to do with the distortion characteristic, though, so if it sounds good stop worrying . The tubes will either live or die now, that's between them and their creator. 3w on the screen is a bit high though. You could try 1.2-1.5k, or even try using a shared R. What do the screens draw with the PI tube pulled?

[phylomatic]

Update

Sorry, it's been a while for a follow-up. Haven't played too much, took a detour working on an old GE record player amp and a couple of pedals, not to mention moving homes in the middle of all that. Anyway, I finally bought different tubes. They are Fender/Groove Tubes that are actually matched Electro-Harmonix so go figure. Much, much, much smaller than the JJ/Tesla's. The JJs are almost the same size as the GZ34, actually they are bigger I think..maybe not. The EHs aren't much bigger than the Mullard (new stock) 12ax7s.

As far as my "problem", more like a quirk/possible problem, there appears to be difference now. The screen resistors now have two watts each. The plate voltage also went up about 15 Volts and the voltages everywhere else went up a bit. It does appear that the JJs are just different animals. Sonic wise I can't tell a difference, well, loudness wise I can't tell much of a difference. The GT/Fender/EH tubes do tend to muddy up when the tone knobs are extreme one way or the other.

I haven't tried just one resistor on the screen yet. I will actually probably do that before I do anything else.

On an opinionated side note, I'm not a big fan of the Groove Tubes. The size of the JJs invoke a little confidence I suppose. It's not just the size of the glass tubes either, the components inside are much larger. The JJs also have a more prominent little electron square on the side of the glass, even though that probably doesn't make a difference, just an observation. I guess I took notice because it was a bit alarming at first. Hopefully I'll get another chance to fiddle with it this weekend and I'll provide another update. I'll probably get to recording some examples, just so I can share with someone that cares. The wife and the cats don't care a whole bunch...

[rockon1]

Dont know a lot about this stuff but Im wondering if perhaps you tried another type of 6V6? I do know a bit about tubes. The JJ is a "freak" amongst 6V6's. It can handle plate voltages of 500v similar to many 6L6's. It also biases up low often compared to others. I like to call it the JJ6VL6. Just a thought. Bob

It does appear that the JJs are just different animals. .

...

Well I do know a litle I guess! FWIW- I love the JJ's because they are freaks. I use them where no other 6V6 dare tread-in amps with 450 volts on the plates. Relatively speaking all the ones Ive tried draw a lot less current than thier counterparts. Great little tubes though. Bob