IC input biasing? Problem.

[jrc4558]

I'm trying to build a hybrid of Red Fuzz and MXR Dist+. That is red fuzz with shunt diodes. I tried the input biasing through the voltage divider (as on the original Red Fuzz) and tried input buiasing with a resistor to voltage divider (as on MXR). I both cases I'm gettin really nasty (in a bad way) gated, spitting distortion sound for about .5 sec and the it just stops. No decay, nothing, just silence.
My question is this:
can it be an input biasing issue? All op-amps I used so far were J-fet input, like LF351, TL071 and such...

Thank you.

[spongebob]

Hard to tell, can you post a schematic?
here for example: http://www.imageshack.us/

If you can measure V/2 at the opamp input then check the feedback loop, is the resistor/cap to ground connected correctly for example?

[jrc4558]

Either like this:
http://www.generalguitargadgets.com/diagrams/rodentsc.gif

or like this:
http://www.generalguitargadgets.com/diagrams/red_fuzz_sc.gif

[niftydog]

voltage measurements will tell you if the biasing is working correctly. Measure the voltage at the biased pin and at the other op amp pins and get back to the forum.