Bass Amp troubleshoot help?

Discussion in 'Amp Central Station' started by Chiogtr4x, Jun 19, 2021.

  1. Chiogtr4x

    Chiogtr4x Doctor of Teleocity

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    OF course, the amp's warranty just expired!

    I told my Bass buddy John ( fantastic player and great friend) I would post his amp issue here, for maybe some help?

    John has little ( but powerful) Mark Bass amp head, and pairs it up with a Mark Bass ( vertical ) 2X10" cab.
    ( I think 2 years with rig now)

    The last few weeks or so the amp is making an intermittent POPPING noise - like a HANDCLAP! Just comes and goes...

    The actual amp volume and sound do not seem to be affected when playing- no other weird noise or distortion- just this 'clap' that invades his amp. He is pissed!

    He thinks the amp needs to be played a while before this shows up.

    He took it to a local service tech; dont know what tests they do, but found nothing.

    We played last night- he used the same Mark Bass cab with his old GK head- no issues.
    20210527_131856.jpg
    Any ideas what might cause a 'slap-pop?'

    Thanks Mucho!
     
  2. Chiogtr4x

    Chiogtr4x Doctor of Teleocity

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    Me again-
    John is not a TDPRI member, but if anyone needs more info on amp symptoms from him, post it here, I can ask him...get back to you. Thanks!
     
  3. Chiogtr4x

    Chiogtr4x Doctor of Teleocity

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    Bumpo!
     
  4. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

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    My cursory thought...
    Since it is intermittent and happens after the amp is warm, it is probably a bad solder joint, or something else that can develop an arc, ie connection, resistor, cap.

    I know it is handy and customary to place the amp head on the speaker cabinet. It is not the best practice do to the vibrations.

    Edit: the Amp tech center or Shock brothers forums may get more tech eyes on this thread.
     
    Last edited: Jun 19, 2021
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  5. Chiogtr4x

    Chiogtr4x Doctor of Teleocity

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    Thanks!
     
  6. Gunny

    Gunny Tele-Holic

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    don't overlook the obvious - it might be his bass or guitar cord.
     
  7. PhredE

    PhredE Tele-Afflicted

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    Another forum that specializes in SS amps and related is Solid State Guitar
    https://www.ssguitar.com/

    There are some really terrific amps techs there.

    Edit: Also, do you know which model or the power rating -- something so we can know which model/type is involved? Sometimes, even a well targeted Google search can lead to a trail of details that point to the problem.
     
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  8. Chiogtr4x

    Chiogtr4x Doctor of Teleocity

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    Thanks, will point John ( bass player) towards this link
     
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  9. Killing Floor

    Killing Floor Friend of Leo's

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    Speaker cable? First thing I’d check.
    Scratch that, I’d check instrument cable and the jack on the bass. Then check the speaker cable.

    Cables are breakable and most people I know lean toward cheaper cables. Without knowing your friend that’s still where I’d start.

    Your story says it worked at the shop, didn’t fail when a tech had it. But let’s assume like any pro, that tech doesn’t take your friend’s cables.
    And you said in so many words it works fine and at some point it pops. That suggests a short. Good luck.
     
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  10. Chiogtr4x

    Chiogtr4x Doctor of Teleocity

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    I'm the OP

    It looks like my buddy's 'pop' issue is going on with the SPEAKER CAB!

    He switched to his old amp head and still getting 'pop' with same cab, so he's gonna get it to a shop, or check it out himself.

    Thanks!
     
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  11. PhredE

    PhredE Tele-Afflicted

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    Don't know much about Mark Bass amps/speakers, but based on your pic above I believe the cabinet in question is one like the below:

    https://www.guitarcenter.com/Markba...0-Bass-Speaker-Cabinet-8-Ohm-1274319726216.gc

    I'd pull the back off and check all wire connections. Look for any signs of wear/heat/stress on the crossover too.

    Like many bass cabinets, that cabinet uses a piezo tweeter and a crossover. Just taking a wild guess here, but a toasted crossover is the thing that I would look at first (if there isn't an obvious connection/wiring problem going on). Chasing down an appropriate replacement might take a little legwork, but should be do-able with a little time.

    *If* it proves to be the crossover, the replacement part will need to be:
    400W or greater,
    2-way (highs -> tweeter, the rest -> speakers)
    3.5kHz (3500hz)
    (I can point you to a reputable source if it turns out to be the problem and he needs one).

    Piezo tweeters are generally very cheap and readily available. The biggest hurdle is probably finding one that has similar frequency range/response and identical physical form as the stock unit. But there are lots of different types available.

    Edit: Some crossovers have fuses onboard. Also check that right away when he/you pull the back off. It might be as simple as a blown fuse.
     
    Last edited: Jun 23, 2021
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