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Strange amp problem. ***!

Discussion in 'Amps and Cabs [BG]' started by vlad335, May 26, 2004.

  1. vlad335

    vlad335 Supporting Member

    Apr 14, 2003
    Latrobe, PA
    At rehearsal the other day my amp lost serious power. I could barely hear it. This happened all of a sudden. I was tuning with my rack tuner on mute. When I took it off mute, I had like a quarter of the volume.

    I narrowed it down between my Alembic FX-1 and QSC PLX-1202 after bypassing everything. Swapped out all cables except the speak-ons ( Don't have spares) Tried a passive bass. Still a faint signal...

    Since the QSC LED's were barely lighting up, I changed the tube in the Alembic thinking maybe that was the problem. No dice.

    Then after a couple minutes, the volume came back.

    I don't understand. Any ideas?
  2. WillPlay4Food

    WillPlay4Food Now With More Metal! Staff Member Supporting Member

    Apr 9, 2002
    Orbiting HQ
    Maybe a loose connection in your amp and heat affected it?

    Love your avatar by the way. :)
  3. Eric Moesle

    Eric Moesle

    Sep 21, 2001
    Columbus OH
    1. Replace/recheck ALL cables - patch cords, instrument cords, speaker cords.

    2. Verify instrument source level is the same, not a pedal or preamp with a low battery, etc.

    3. QSC PLX "might" have a ribbon cable problem that exhibits this behavior, which has been identified by QSC as being some PLX models made in '98 and '99. If you e-mail QSC your serial number, they'll let you know. If so, even if OUT of warranty, they will cover the repair as well as shipping both ways. Excellent company service, as good as it gets.
  4. Ok..the volume came back, did it ever disappear again?
  5. vlad335

    vlad335 Supporting Member

    Apr 14, 2003
    Latrobe, PA
    I am certain that 1 and 2 of you post was not the problem. As for number 3, that is interesting. I will look into this.

  6. vlad335

    vlad335 Supporting Member

    Apr 14, 2003
    Latrobe, PA
    I havent tried the amp since we last rehearsed. We are getting together tonight.

    Getting ready to play out soon. I hope this doesn't happen on a gig :crying:
  7. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    What Eric said. ;)

    Vlad, send your serial number to me at bob_lee@qscaudio.com. I'll be able to tell whether your amp has a likelihood of a ribbon cable problem. And if so, I'll tell you how we'll take care of it for you.
  8. vlad335

    vlad335 Supporting Member

    Apr 14, 2003
    Latrobe, PA

    Wow! Thank you!

    I will be heading over there tonight.

    Talkbass is a great place I tells ya.