Pink Purple Fuzz (Bearfoot, BJFE) oscillation problem

[Solder of Destiny]

I built the three-knob Pink Purple/Fuchsia Fuzz from this stripboard layout:

I used an MPF4393 in Q1 and an MP38A in Q3. I used 1n4001 as D1 and D2. Everything else is as in the layout (or at least that is my belief).

The pedal works but I'm getting oscillation in the higher reaches of the fuzz pot with the Nature in certain spots. The oscillation persists even with guitar volume rolled all the way off.

It's the same issue as another forum user experienced in this post. They never found a solution.

Here are some photos of my build. It's in a test box I've successfully used many times so I know the 3pdt switch, jacks, power and grounds are wired correctly and working.

Other people who've built the effect from the same source as me have reported similar oscillation problems in the comments there, so I'm guessing it might be an issue with the actual layout rather than something I've done wrong, but others in the comments report their builds are working well with no oscillation so I dunno.

Maybe some experienced fuzz builders here have some suggestions for fixing oscillation issues in general that I could try? Or perhaps can see an issue with the layout itself.

 

[Solder of Destiny]

Anybody out there?

 

[jwin615]

Could try a few things. Try touching a 20-220pf cap between lugs 1-2 and lugs 2-3 of the nature pot with the pot positioned to a section where it oscilates.
Could also try adding a miller cap to Q2.

 

[Solder of Destiny]

Could try a few things. Try touching a 20-220pf cap between lugs 1-2 and lugs 2-3 of the nature pot with the pot positioned to a section where it oscilates.
Could also try adding a miller cap to Q2.

Thanks for the suggestions. The only cap I have in that range is a 100pf and it doesn't really help, although it does change the pitch of the whistle a bit!