Ampeg V4B no volume on input two?

Discussion in 'Amps and Cabs [BG]' started by corinpills, Oct 29, 2017.

  1. corinpills


    Nov 19, 2000
    Boston, MA
    Well, here's new thing out of nowhere. I usually use input two on my old V4B simply because it has a bit less hum. Starting just yesterday, there's almost no volume on that input. If I crank the volume knob all the way up on the amp, a bit of bass comes through. There's no crackling or spitting as I turn the knob, so I don't think it's a dirty pot. Relatively new tubes that were biased by my tech (I'm waiting for it to cool down before I pull the 12ax7 in the pre). Assuming the tubes are OK, any of you have any ideas? Volume pot just wore out? That doesnt seem likely.
  2. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Good chance it is the pre-amp tube. V1 is channel 1; v2 is channel 2.

    One step at a time. Assuming the tube is alright, check the gray shielded wire that runs from the channel 2 pot to the board. Sometimes the wire breaks at one of the ends. It could be that the tube socket needs to be cleaned with deoxit. Many possibilities.
    corinpills likes this.
  3. corinpills


    Nov 19, 2000
    Boston, MA
    Thanks for the suggestions. I'm going to check that out when I get home from work.
  4. BassmanPaul

    BassmanPaul Inactive

    Put V2 into the V1 socket and V1 into the V2 socket. See if the problem follows the tube.
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