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GK MB800 problem?

Discussion in 'Amps [BG]' started by Stumper, Dec 11, 2013.

  1. Stumper

    Stumper Guest

    Likes Received:
    Hi guys, I yesterday received a used GK MB800 head to power my SWR workingman's 4x10. I set it up, following the User Manual, put the master at 12 o clock and adjusted the gain. It sounded great initially, but a few minutes in, the signal faded out to nothing. Turned the amp off, then back on, and it worked fine for both an active pickup and passive pickup basses. Now I find that flipping the mute switch on will mute the signal, but when I flip it off again the signal does not return. Any ideas? Thanks!
  2. B-string

    B-string Supporting Member

    Nov 21, 2008
    Likes Received:
    Maybe a damaged or sticky mute switch. Shipping damage claim?
  3. Jim Carr

    Jim Carr Dr. Jim Gold Supporting Member

    Jan 21, 2006
    Likes Received:
    I have one of these. How quickly did it fade out? The pots on those heads are pretty easy to turn, so if the head was on the cabinet, the vibration may have turned the levels down. Has the gradual level drop happened again? A thermal shutdown would be almost immediate, I think.

    Any more info?

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