aye, makes sense. Just wondered if was kind of the nature of the beast so to speak.
To some extent, yes, if you're getting noise and buzz. This is the quietest one I've made ...
http://www.youtube.com/watch?v=EA85cFCrt-ENote the first comment on the video:
"Lotta noise."
(To be fair most of it's at the end when I put a single coil guitar right in front of the speaker ...)
However, "outta control" from your description sounds like maybe you mean it's ... oscillating, maybe? Making weird gurgly noises at the highest gain settings and choking up? What pickups are you using and are they high output? I can't guarantee that you've built it properly if it's oscillating, but of course, if you're only getting the problem at max gain -- don't turn it all the way up! The best thing this pedal does is edge of breakup/touch sensitivity, where it's clean much of the time and then snarls when you dig in. It's not what I think of as a "linear" overdrive that simply distorts more as you turn up the gain, more like a gating fuzz that doesn't distort until it hits a certain point and then it's all fuzz all the time. Think of the gain knob as more like a control for setting how low the threshold for that breakup will happen.
And a metal enclosure will provide shielding, but only if it's grounded. There are grounding schemes and modulation pedals that will be okay in a plastic enclosure, but I'd never go plastic for a high-gain circuit.
