Power Supply Noise in Clyde Deluxe Wah with Curious Fix

[drummer4gc]

Hey all, I've got a predictable problem with an interesting fix that I'm hoping to understand better.

I have a cheap 9v regulated adaptor - not our favorite name brand, works reasonably well most of the time, but is certainly not high quality. When using it with my Fulltone Clyde Deluxe, I get a ton of noise when the pedal is in the heel position, and it is reduced significantly when I come up from heel-down a little bit. Noise all but disappears when I use the pedal with the battery. No real surprise.

However, the Clyde deluxe has an "Input Gain" knob, which essentially lets you dial in resistance in series with the input signal. With the gain turned all the way up, the resistance goes to 0, and the power supply noise disappears. When even a touch of resistance is dialed in, the noise returns full force.

Clearly the noise is due to the power supply - what I'm wondering is, why does it disappear when I kill the series resistance?

Thanks!
Matt

[PRR]

Power is fed from supply to first amplifying device's input, to set a DC bias.

If the power is crap, you get crap at input.

If the input is fed from a "solid" source, some of that crap is absorbed by the source.

As you add series resistance, the source absorption is spoiled.

While there are other techniques, a key tool in Audio is non-crap supplies. Add filtering to this one, or buy something better.