ABY-X Pedal issue

[Jimi W]

Hi,
A while ago I built a custom amp switching pedal for a friend. It's an ABY pedal following the Bigmans layout with an extra output for a 3rd amp (amp X). I wired it so the input signal goes to a switch (switch x) and then straight through to the ABY circuit. When switch X is pressed the signal also passes to the X output. When the X switch is off the X output is sent to ground. I was surprised it worked but he said it was fine and there were no ground/hum issues.

It's been fine for weeks but he's now added a phase shifter in front of amp X and when switch X is off he says he can hear the phase shifter effecting some off the background hum/noise.

Any ideas what's going on and how I can fix it. I'm guessing the X signal that has Ben sent to ground is getting back into the signal chain.

Cheers Jimi

[slacker]

There's nothing wrong with your switch. It's probably just his phaser is noisy and even though your switch is grounding the input it's phasing its own hiss and sending that to the amp.

[Jimi W]

Cheers for the reply Slacker. I've come to that conclusion too. I thought the phase signal was being heard through all 3 amps but it turns out it's just the one amp. I could always come up with a way of killing the signal after the pedal rather than before. That'd sort it.
Going to go and witness the 3 amp setup this week. Complete over kill in my eyes!
Jimi