Buzz Through Mesa M6 with Nothing Plugged In?

[j.kernodle]

I picked up a NOS Mesa Fathom head a few weeks ago (renamed the M6 Carbine).

The amp sounds great when playing through it, but if I unplug the instrument cable from the front panel I hear an intermittent crackling and buzz through the speaker cabinet.

Its almost as thought I've got a cable plugged into the amp with no instrument at the other end, but as I said, there's no cable plugged into the front panel at all.

I have nothing going into or out of the back panel except my speakon cable to my cabinet.

I guess its a short somewhere in the input jack, but on the chance anyone's had experience I'd like to hear your thoughts.

Head is still under warranty.

[WingKL]

If nothing is plugged in, it should not be buzzing. Have you checked your AC mains wiring to make sure it's correct? There could also be noise in your mains wiring. If it is neither of these then there is probably an issue with the amp. Try plugging it in somewhare else and see if you have the same problem.

[BassmanPaul]

If the amp has an effects loop try jumpering the send and return with a signal cable and see if that helps.

Paul