Ampeg V-4B Reissue Hum

Discussion in 'Amps and Cabs [BG]' started by Alex Huddleston, Mar 8, 2018.

  1. Hi, I just picked up a demo model V-4B reissue off of sweetwater and there is a hum coming from it. Dead silent when in standby, only very slight hum with nothing plugged in (only audible when gain and volume are dimed). Plug in a cable to the input with no instrument and the hum gets louder. Plug in a bass and it gets even slightly louder (the worst with my Rickenbacker 4003, but that has to do with the high gain single coils I would imagine). Any ideas of what could be wrong? loose preamp tube, bad power? Should I just return it? I love the the tone of it so much up until I noticed it was humming a lot.
  2. coreyfyfe

    coreyfyfe Supporting Member

    Nov 19, 2007
    boston, ma
    The input jack likely shorts to ground with nothing plugged in. If you've got no noise with the gain and volume cranked and nothing in the input but you get noise with a cable plugged in then the issue is likely somewhere between your cable and the V1 tube. Could be a noisy tube, could also be induced noise from your surroundings, especially with a rick since the coils aren't hum cancelling.
  3. Wasnex


    Dec 25, 2011

    If the amp is hum free before an instrument is plugged in, it's unlikely but not impossible the amp is the problem.

    Check the outlet for a good ground. Are your pickups humbuckers or single coils. FYI single coils pick up lots of EMF. What gain and volume setting are you using when you are playing? I don't know any amps that are dead silent with gain and volume dimed. How much does the hum vary if you move around? Try a different cable.
  4. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    Likely nothing at all wrong with your amp.

    What you are hearing is noise being picked up by the unterminated cable, and then when you plug the bass in, noise picked up by the pickups. Your symptoms match this condition pretty exactly.
    P-oddz likes this.
  5. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    Noise with the cable plugged in, but nothing connected to the far end of the cable is entirely normal. An unterminated cable will pick up noise (electromagnetic fields) in the surroundings.

    Because there is no noise without a cable, the jack shorts the input, it's almost certainly not the amp or the V1 tube.
    P-oddz likes this.
  6. Sorry to finally respond to my old thread but I think the amp is most likely fine. Plugged in my P bass and there was no detectable noise at decent volumes. I did get a very slight 60 hz buzz from the P bass --> Ampeg --> Peavey 2x15 at my drummers house for practice the other day, but I'm guessing it could be dirty power or just picking up something from the room? The amp was plugged into an extension cord and I was running a darkglass B7K into the front of it. Again, the noise was very faint, almost inaudible.

    Thank you again for the responses!
    agedhorse and Wasnex like this.
  7. AmericanFenderJazzMan

    AmericanFenderJazzMan Guest

    Jan 24, 2016
    had same problem...get a Furman power conditioner online at Reverb or Ebay,,,it kills all'll be happy you got one :)
  8. BassmanPaul

    BassmanPaul Inactive

    A power ‘conditioner’ is nothing more than a glorified power strip. It will not affect the background hum from an amplifier.
  9. BassmanPaul

    BassmanPaul Inactive

    Some hum is normal from pretty much any AC powered device. If you stand too close to the amp you will hear more hum as the instrument's pickups will react to the stray magnetic fields emanating from the power transformer.
    Last edited: May 15, 2018
    agedhorse likes this.