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GK MB150 question

Discussion in 'Amps and Cabs [BG]' started by Low_blow, Jan 14, 2006.

  1. Low_blow


    May 14, 2005
    I bought my MB150E-III head and an MBX112 cab about a month ago. It sounds fantastic with my YamahaTRB-5 and all other basses I plugged in, but I found that there is noticable background hiss, the hiss from the amp, not the bass (I tried to lower the preamp/master volume, then disconnected the cord, but the hiss remained). In fact, the hiss is not very loud, I can hear it only when I stop playing, but it exists.
    Is it common with these amps?
  2. Indiana Mike

    Indiana Mike

    Nov 18, 2005
    Having the ms 150s-lll head and same cab I have never had that problem. I wish I could help but I have no clue as to what your problem could be. I know mine does not hiss even with the volume/level out/input gain above 2 o'clock. I know all the talk about cheap vs. expensive cables but I use a$ 20 heavy duty speaker cable with mine.

    Not to question your ability or knowledge but I have to ask,are you using an instrument cable for the cab ? A speaker cable has two seperate wires while a instrument cable has one with a shield around it. You can ruin your speaker using an instrument cable.
  3. Low_blow


    May 14, 2005
    Thanks for your reply. I use speaker cable, of course.

    "You can ruin your speaker using an instrument cable."
    In most cases it won't. If you connect your amp and speaker via instrument cable the impedance raises and so does the amplifier load.
  4. dave64o

    dave64o Talkbass Top 10 all time lowest talent/gear ratio! Gold Supporting Member

    Jun 15, 2000
    Southern NJ
    I have the MB150S combo and there is *some* hiss even without an instrument plugged plugged in, but it's very soft. If I'm less than a few feet away and pay attention I can hear it, but it's not very noticeable. If I'm focused on something else I wouldn't hear it.

    Now, I can really hear the hiss from the tweeter in my Nemesis NSP115 cabinet. Maybe that warps my perception of the GK, but I don't think so. I just checked it without the Nemesis plugged in.
  5. Low, I tried out the same model GK head last year, and ran into the same hiss problem.

    It only happens on some electrical circuits, though. Are your outlets at home grounded, or are they two-prong outlets? I have both in my house, and the amp hissed when plugged into a two-prong outlet with an adapter. It still hissed, but not as much, plugged into one of the house's 3-prong, grounded outlets.

    I played it out a couple of times, and did not hear the hiss, even with dimmer packs in the venue.

    I bought it from RMC (was Rik's), which is close enough to me that I could go to the warehouse, and told them that I was hearing hiss in certain circumstances. The tech there plugged it in and it was fine. I still got a refund, because the hiss was bad enough in some cases to be objectionable.

    In my opinion, the power supply in the 150E and S amps is susceptible to less than optimal AC line conditions. That may be what you are running into.
  6. bassaroo


    Dec 9, 2005
    I've got the MB150 - 112. It does hiss a lot if the limiter is on - otherwise, no hiss. So, I never use the limiter.