Fuzz Face squeal. Why is this?

[Focalized]

I just built this vero SI Fuzz Face. I get a squeal when the Fuzz is 80% +. I get this with my BYOC Ultimate Fuzz too. Is there a fix for this?

Also that layout uses A pots. I used B pots for now. Does that make much of a difference if i'd want to keep that fuzz maxed?

[tcobretti]

The pots don't effect it.  Si FFs will oscillate if the HFE of the transistors is med or high.  Use lower gain transistors and it will go away.  Another possibility is to put a 50pf  - 100pf cap across the collector and base of Q1.  You'll lose some high end, but the oscillation should go away.

[hellwood]

yeah, i feel ya. that happens to me too when my 100 watt marshall is cranked on 10 and my guitar is 1 inch from the speaker!

[rikkards]

I have the same thing with my Thor around 80% gain if I don't have the bright switch activated. Really weird. I may try a different transistor and possibly see what happens with the 150pf as recommended here

[foxfire]

yeah, i feel ya. that happens to me too when my 100 watt marshall is cranked on 10 and my guitar is 1 inch from the speaker!

you see mine doesn't start to squeal until my guitar is actually in the cab behind my speakers?