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Markbass 121H - Combo Head 2 - Problems with pre/power Amp?

Discussion in 'Amps and Cabs [BG]' started by Chris Bold, May 23, 2020.

  1. Chris Bold

    Chris Bold

    May 23, 2020
    Hey guys,

    my 'used to be' intermittent problem with this Combo just turned permanent.
    It has happened maybe 1-2 times in the past 2 years, for a couple of hours .. then went away.

    The amp makes a strong background noise, sort of like a distorted ringing .. don't know. The sound of the bass does come through, and doesn't seem very distorted. (of course, ringing/noise is still there). This happens indifferent of whether a bass is plugged in or not. Gain / Master Knobs (or any other ones) don't influence the level of the 'noise'

    I've uploaded a video (Tweeter is disconnected, as i first thought it was on it's way out. With tweeter on, noise is only louder) with the sounds its been making. Please have a look and let me know if the issue is familiar or something .. :)

    Thanks for the help!
    Last edited: May 23, 2020
  2. Doufuss


    Mar 4, 2009
    I had one of those. Loved it. It blew up. The authorized repair facility here couldn't fix it due to parts not being available.

    The end.

    Hope you have better luck than I did.
  3. Chris Bold

    Chris Bold

    May 23, 2020
    Oh snap. Sorry to hear that & really hope i can find a decent fix for it.

    Otherwise .. it shall be the first and last MB. (despite tone..)
  4. Doufuss


    Mar 4, 2009
    Don't give up yet. Worse comes to worst you could pick up a new head (new to you/used) and it'll fit right in the opening. You'd have to takeoff the cover IIRC. Other guys have done it, see this thread. Markbass Combo head replacement

    That's a great sounding cab. Really nice and smooth and very broad frequency response. I used mine with both a 112 markbass cab and the 210 cab and it sounded huge.

    Really wish I had kept it, but I flogged it cause I was miffed about the head. Dumb.
  5. Chris Bold

    Chris Bold

    May 23, 2020
    Thanks Doufuss! : ) Will definately try to get it fixed. It's been my go to for small sessions/jams/shows exactly due to the response & sound + the 'enourmous' weight.

    I come from the 'guitar world' originally, and I'm used to less than stellar reliability from old tube amps, which crack up here & there every now and then, but that's fine, it's what they are and their analog tech is easier for me to fix. The MB i've bought new in order to not even think about things like repairs. Just a pick up & go.

    Will keep you posted, atm i'm looking for a good tech in my area to have a look at it.

    Cheers & stay safe
    Doufuss likes this.
  6. PhatBasstard

    PhatBasstard Spector Dissector Supporting Member

    Feb 3, 2002
    Las Vegas, NV.
    Any of the Little Mark series heads will retro fit into that cab.
    They all use the same internal frame.

    Remove the top 4 mounting screws of the cab.
    Slide the (unplugged) old head out/forward.
    Remove the top plate from the new/replacement head.
    Once the plate is off, you may have to remove some of the foam strip,
    on either side of the internal frame,
    that's covering the holes for the combo's top 4 mounting screws
    (You'll see where they are on the old head).
    Slide in the new/replacement head until the first one of the mounting screws lines up.
    The other 3 should now be a breeze.
    Plug everything back in.

    I've done this on several of their combos with several of their Little Mark
    or Combo Head (a rebranded LM II) or Combo Head II (a rebranded LM III) amps.
    Kaplan and Doufuss like this.

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