Help DIY 5E3!

[MWJB]

Whoa! You said before you could get to "5", did you change the rectifier back to NOS 5Y3?

Whoops! You're going down the road of "Shotgunning". It is possible that one of your Sozos might be defective, but all 5? Very unlikely!

If one of them was leaky you would have low dc voltage on the corresponding plate & muddy tone.

[nosetocar]

Hello.
I also think this, but I can not find the faulty one and I decided to change them all.
I also plan to change all resistance. I remeasured and many are +20% (for example, measure inputs jacks 1236 ohms). Today I played a while and have noticed the farting only when I play two bass strings together, for example a G Major on the third fret. This makes me think it is a problem of too many low frequencies. It would be a good idea to change the 0.1 mfd mfd by about 0.047?

[MWJB]

Bare in mind that low frequencies stress the amp more, so will also highlight any issue caused by too much high end (e.g. parasitics). Do you still get this farting in the Normal/Mic channel at comparable settings?

That said, sure try smaller coupling caps if you like...0.022uf accross the board might be overkill, either all at 0.047 might work, or 0.1uf feeding the 6V6 grids and 0.022uf in the preamp?

I am pretty confident that if you change all the resistors in the amp, you still won't cure the problem...most values can be halved or doubled and the amp should still work right.