Depth noise?

[khenegar]

I noticed that when I change my phase switch setting on my depth sub a thumping noise comes out of the speakers in the depth! My other depth does not do this! If anyone has a depth could u see if yours does this! Thanks

 

[Brad225]

None of my 4 Depth i's thump.

 

[Nutshell]

My Depth only gives a loud thump when I remove the mains plug from the power strip. I always unplug the IEC first, which doesn't cause such a noise.
But otherwise: no noises.