FX5X Squeal

[VanWhy]

So, not sure if this is just normal for this circuit but, I'm getting some annoying squealing at high gain.

I built this to the FX-55B Supra Distortion specs. A buddy of mine really wanted this for nostalgic purposes.

I first had the A500k in for the gain but all the Distortion was only at the last 5% of the range. And when it got to maxed out it squealed like crazy. Not very usable. I swapped the A500k for a C100k and it made the range more usable but its still squealing at the end of the range and especially maxed. Went back to the A500k and hate it.

I installed shielded cable, no change. Changed to a buffered bypass, no change. I did change the IC's for TL072IP's and it made a little difference but still squealing. Seemed to alter the tone slightly too (at least perceived).

1. Is this normal for this circuit? It doesnt seem like a super high gain circuit.
2. Is there something I can do to tame the gain? Component value change?

Or am I wasting my time and just stuff the box with a TS808 and tell him its a FX55B?

Video of the squealing. TL072 in IC1 with C100k Gain pot. Using humbuckers

 

[RICHB555]

I built one a few months back and I get the same results with mine at full gain, so could be normal for the circuit. I can even get it to do what you did in your video with moving the gain and tone knobs when ringing out chords. I noticed I can temper the squeal by limiting ringing notes or chords and just play steadily. Seems like it could be a pretty high gain pedal so that might explain the squeal prolonging notes at the highest gain setting.

I have an original DOD Supra Distortion somewhere but couldn’t find it to A/B with the clone.

Hope this helps!

 

[jimilee]

Are your connections to your stomp board shielded as well? That is a big source of oscillation right there. I built a pedal last week and had to remove the stomp board. That worked for me.