18watt tmb works great until plugged into pedal board

[William Martin]

Just finished a ValveStorm 18watt TMB built from their layout. This probably the fifth one I’ve built and I’ve never had this problem.
Amp sounds great when I plug my guitar directly into any of the three input jacks when I go through my pedal board with an ABY box and just a reverb pedal on it makes a horrible low rumble.
I’ve checked my wiring and components and I can’t find anything amiss
Here’s a photo of it and tomorrow I can post some voltages.
Anyone experience anything like this? Any ideas?
Thanks everyone any input is much appreciated.

 

[PelliX]

Amp sounds great when I plug my guitar directly into any of the three input jacks when I go through my pedal board with an ABY box and just a reverb pedal on it makes a horrible low rumble.

Same pedalboard on another amp is fine? Eliminate which part of the chain is causing the rumble. Is the amp properly grounded, and grounded in the same way as you other (problem-free) amps? Is this rumble reminiscent of 50/60Hz hum?

 

[William Martin]

T

Same pedalboard on another amp is fine? Eliminate which part of the chain is causing the rumble. Is the amp properly grounded, and grounded in the same way as you other (problem-free) amps? Is this rumble reminiscent of 50/60Hz hum?

Thanks, ground loop rumble
All good now!
Cheers