RAT Breadboard Oscillation / Feedback

[spargo]

I recently breadboarded a RAT, trying it both with a TL071 and NE5534.  All works well with the exception of turning the volume, gain, and tone knobs to full or close to full.  Once I hit a certain point there is an extremely loud and high pitched tone that sounds a lot like amplified mic feedback, but worse.  This happens with nothing going on with the guitar.  If I pluck some strings it goes away while the notes ring out.

I'm a bit puzzled since I've breadboarded, built and boxed up a RAT before without this issue.  I did, however, use an LM308 in the last one.  Anyone have an idea of how to rid it of this obnoxiousness?  I'm hoping to not hear "just don't turn it up that far."  What's the fun in that? 

[ode2no1]

this could have nothing to do with it...but have you tried messing with the compensation cap? maybe upping it a bit since the lm308 is way more lofi than the chips you're using.

[spargo]

The 30pF?  It's removed since these chips are internally compensated.  Replacing it makes no difference.

[anchovie]

Breadboard + High Gain + No Shielding = Unwanted Oscillator!

You may find this stops when you've got the parts soldered onto a board and mounted in a metal box. If it doesn't, use shielded wire.

[spargo]

Oddly enough, grounding pins 1 and 8 of the TL071 (which were left open) takes away the feedback.  But it does change the background noise slightly, and possible also the tone of the pedal just a bit.

Do you think pins 1, 5 and 8 should be left open without problems?

[spargo]

For the sake of science...

SOLUTION:

Even if this was just a "breadboarding issue", I was hoping to solve it to give me confidence it would not do this when boxed up.  I did.  Yes, wiring was the issue.  Specifically, I had a fairly long wire running from the 1M resistor after the voltage divider across the board to the input cap.  Grabbing it with my hand made the high pitched squeal go away and induced a loud, low buzz.  Moving the voltage divider network across the breadboard close to the input cap fixed the issue. 

[ode2no1]

weird...today i opened up my rat clone and decided to try a couple different chips in it since it just hasn't been doing it for me lately. i only ever use it in ruetz mode and the lm308 just sounded too saggy. i wanted something tighter/punchier. the tl071 ended up winning out over the lm308 and tl070. funny thing is, just for kicks i flipped the little dpdt that goes from ruetz to stock and i got the same crazy oscillation you described when the gain was above 2 o'clock. my guitars volume knob controls the pitch too. anyway, not really an issue since i literally never use it in stock mode, but i remembered this thread and just wanted to share haha.