MXR phase 45 clone

[peterg]

I'm building a mxr phase 45. I haven't matched fets yet but plugged it in to check progress. I'm getting a loud whine when the effect is on and in the background when on bypass with fets in the sockets or not. The 250k trim pot, which I'm going to narrow doen to 10k and outboard, has a tight range and the speed pot seems to be doing what it should. Any ideas about the noise? Its even there with tha amp at 0.

[brett]

Hi
If it's there when the amp is at 0, and we assume that the amp isn't faulty, the pedal must be injecting a heap of interference via the earth/ground (the amplifier amplifies the difference between the signal and ground, so if there's no signal, but an unstable ground, there will be lots of output). However, this is unlikely if the ground of the amp is good (ie actually connected to mother Earth and VERY stable), so be careful with that amp. If the ground is poor, it has the potential to go live.
cheers

[peterg]

Thanks Brett. Got that issue sorted out. Bad soldering! Need to start a new post re weird grounding...