Squeel in a Soho-similar amp

[arjepsen]

Hey.
I built an amp a bit similar to the 65 amps soho.
But I have some issues with it:
If I use my strat neck pickup (in particular) and max the volume and treble, I get a squeel. This is only WITHOUT the bump circuit or the +/- boost engaged.
I'm assuming that I got oscilliations somewhere.
I have tried putting 10k grid stoppers on the V2A grid, and on the pi input. It dampened it a bit, but did not fix it. I run a shielded wire from volume to V2A and also from treble to the cap into the PI - didnt fix it.
Interestingly, if I switch the OT leads to the el84 plates, the squeel a not as loud, and higher pitched, but still there - and also when only lightly plucking the strings, it sound like it's farting out.... but if I understand correctly, in an amp like this with no NVB, switching the OT leads shouldnt change anything?
I will try to upload a pdf with the layout.
Hope you guys have some insight

[Stevem]

The first thing to try is to shorten the length of your stage to stage grid wires by making your plate wires longer and putting the down stream coupling cap right on the tube socket.



Can you post up a few good clear gut shot photos?

[arjepsen]

It's a bit of a mess, due to me trying various things to fix it, but here are some gutshots.