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Less than one year old MB Fusion Problems.

Discussion in 'Amps and Cabs [BG]' started by powellmacaque, Jan 26, 2012.

  1. I've been using my MB Fusion pretty solidly for under a year now (into an MBE 115). I went to play the other day, and the tubes warm up, I get the distorted (but not like a blown speaker) sound of my bass for about a second, and then my sound fades away to nothing within a matter of seconds.

    I really don't want to have to send away to GK, but I think it is under warranty still so I might have to. This is my only head so I'm kinda s.o.l. either way here. Could this be an easy fix?
  2. BassmanPaul

    BassmanPaul Gold Supporting Member

    Aug 25, 2007
    Toronto Ontario Canada
    Take the amp back to where you bought it and use the warranty. It's what it's for.

    Edit: Trying to fix it yourself will void that warranty!
  3. Oh I know that, I was just trying to see if maybe what I was describing could be something simple like an AC chord failure or something like that. I got it from musician's friend, so would I have to send it back to GK (I didn't take out an extra warranty, but it's only been 8 months).
  4. username1


    Dec 28, 2005
    alberta canada
    I would bet its a tube but they are a pain to change in that amp. You have to remove a small curcuit board and the transformer to have room to take out the tubes "i did it on mine" so i would take it back because it might void your warrantee.
  5. wave rider

    wave rider

    Jan 5, 2005
    Try running an instrument cable between the FX send and return jacks just to eliminate a dirty jack as the culprit.

  6. OK, so I ran straight from my bass into the FX return jack, and it worked (obviously without any pre-amp interaction of course).

    What does that mean?
  7. What wave rider meant: connect FX send and FX return with a short patch cable.

    Some MB users have experienced problems with dust in the connectors between pre and power-amp sections.

    If patch cable gives you your amp back then you have that problem.
  8. Ran patch cables from send to return, plugged into the input, got nothing.
  9. BassmanPaul

    BassmanPaul Gold Supporting Member

    Aug 25, 2007
    Toronto Ontario Canada
    Send it to GK while you still have a warranty. Anything else and you could be faced with the full cost of the repair!.
  10. Gorriot


    Nov 26, 2013
    Hi everyone, new to this forum.

    Same problem here with MB Fusion I think.
    I bought one about one year ago and had some pan issues (never stop, start when turn the amp on etc..) and after two "send-back" to where I bought it (big internet seller in europe) they gave me another one... but not a new one. Front where buttons are not exactly the same in the new I had, no white line as I had with the first one.

    And now a problem, "bzzzz" when I turn the master and one time sound disappeard. I connect a jack between effect send in and out as said but the buzzzz disappear only if one side is not completly engaged in the hole... my sound disappear unfortunatly too when doing that.

    If someone as ideas and know this problem thanks to reply because my big internet seller keep the amp several weeks to work on it (and didn't find anything befaore I add an exchange with a Gallien Krueger Technicians who seem to convince them to change the amp) and I have only one... and need it.

    Thanks in advance.
  11. JxBass

    JxBass Supporting Member

    Aug 5, 2008
    I had a similar problem with my Streamliner 900 awhile back. Jeff Genzler asked me to plug straight into effects return and it was clean. It confirmed that it was a bad preamp tube, replacing it fixed the problem.
  12. Dave Curran

    Dave Curran Lilduke

    Jul 27, 2013
    Sub'd as this is a great diagnostic technique.
  13. A previous thread on changing tubes in the MB500 or MB800 says to remove the cover and the three tubes are right there on top. Nothing has to be removed. Someone who has one might give some input here. One is on my GAS list for now.

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