Bad MPF102 FETs cause static in Prof Tweed?

[armstrom]

I built a Professor tweed kit from OLCircuits and it produces a lot of static. It sounds like an FM radio tuned close to a station but not right on it. (The guitar tone can be heard through the static, but the static is still pretty loud). The static disappeared when the FETs drain voltages were way out of whack (less than 2.5V or more than 7V)  the closer I got to the bias voltage the worse the static got.

I had a hell of a time biasing the fets. Less than half a degree turn on the 100K trimpot would cause the voltage at the drain to jump from 2.5 to 7V. This happened on all three FETs. On a hunch, I tried replacing all three fets with J201s (OLCircuits provides three of these in the kit also). These were MUCH easier to trim out with the pot behaving as I would expect it to... And... the static is gone. However, I think all 201s produce too much gain for this pedal.

Could all three MPF102 FETs be bad? That seems unlikely, but I guess it's not out of the question. I'm at a loss as it seems everything else is working fine (as evidenced by the fact that the pedal works with the J201s)

Any advice would be much appreciated.

-Matt Armstrong

[armstrom]

I just wanted to post a follow up... After further experimenting with the all-J201 professor tweed circuit I've noticed a fair amount of background hiss. (Not horrible like the static I was getting, but noticeable) Is this typical of the professor tweed circuit? I know tube amps hiss, but I thought a lot of that was from the use of AC to drive them. I would like to eliminate this hiss if at all possible.

-Matt