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svt4 pro - sounding a little farty

Discussion in 'Amps and Cabs [BG]' started by jcroxford, Jun 3, 2018.


  1. jcroxford

    jcroxford

    Jan 7, 2017
    Sacramento CA
    So I just scored an svt4 pro with 2 pr410hlf cabs. When I was testing it out (in stereo) I didn't notice any issue, but then when I got it home and hooked up the bridge mono cord, it was lacking in power and distorted sounding. At first i though I made the cord wrong, but double checked it, and it was right.

    So I then tested out each amp side on its own, and its the B side amp. A side is clean w/ lots of power. B - farty, very low power.

    I was hoping maybe it was just a tube. So I bypassed the preamp, plugging a sansamp RBI in. A side fine, but B-Side same issue.

    Does this sound l like anything that can be fixed at home or easily? Or am I facing the repair shop. Any advice would be appreciated. THX!
     
  2. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    No, this is not a home fix. The B channel power amp has a failure which is why you also experienced the symptoms in bridge mode (which places the amps effectively in series)

    Fins an Ampeg authorized service tech and it should be a straight forward repair.
     
  3. jcroxford

    jcroxford

    Jan 7, 2017
    Sacramento CA
    Thanks. I will try and find a service center around town.
     
  4. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    See if Rainbow Electronics is Ampeg authorized.
     
  5. BasturdBlaster

    BasturdBlaster

    Feb 19, 2012
    Crandon WI
    My SVT4 did something similar to this and in my case it was the preamp in/ poweramp out jacks that needed to be cleaned. Maybe try some short patch cables in the FX loop and the preamp in/poweramp out loop on the "B" side of your amp.
     
  6. One of my 4pros had a cold solder problem. Maybe this could be part of the problem on yours.
     
  7. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
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