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Vox AC15 problem?...

Discussion in 'Glowing Bottle Tube Amp Forum' started by justrfb, May 20, 2015.

  1. justrfb

    justrfb TDPRI Member

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    Hello All.
    I am working with a Vox AC15 amp that has a peculiar problem I am hoping you have an idea as to what might be going on... It is a year or two old, all the tubes glow (so I don't think it is a tube issue...) but it is barely audible when playing and one channel is slightly louder than the other... Don't take louder to be loud at all, both channels are just barley audible no matter what I do to the volume or any other knob. I don't believe it is a speaker issue either. Any ideas please? Thanks for your help.

    Sincerely,
    Rich
     
  2. KyAnne

    KyAnne Tele-Afflicted

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    Assuming you've checked your input cable and instrument, I'd start at the power supply.
     
  3. jhundt

    jhundt Doctor of Teleocity

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    try another speaker and speaker cable, too...
     
  4. clintj

    clintj Friend of Leo's

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    Swap tubes anyway. The majority of the time a working amp starts acting weird is tube related. Even if that's not it, you'll need a spare set of tubes at some point.
     
  5. Iceman

    Iceman Tele-Holic

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    This. I don't think that just because a plug is glowing that is not faulty.
     
  6. Wally

    Wally Telefied Ad Free Member

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    El-84's are gone....definite possibility.
     
  7. robrob

    robrob Poster Extraordinaire Ad Free Member

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    I'd start with the tubes. Do you have any spares or can you borrow some tubes to swap for troubleshooting purposes? At the very least move the 5 12AX7's around and see if the symptoms change. If they don't you can rule out preamp tubes.
     
  8. pete-strych

    pete-strych Tele-Holic

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    If your output tranny went, your volume would be super low (that is a worse case scenario for your wallet). Did you blow any fuses? Last time my AC15 clone was popping fuses, the rectifier tube went bad. Same thing happened with my old Champ's rectifier tube. Any crackling noises before the volume went away? My buddy's AC30 did that after the output tubes (7+ yrs old) just bit the dust. Does your model have an EF86 preamp tube--they can be unstable (yet, I've never had a problem with one)?
     
  9. justrfb

    justrfb TDPRI Member

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    Thank you and I am sorry for the delay in responding to your suggestions and help... I do appreciate your suggestions and will have time to look at the amp soon... I will start by checking all of your suggestions and will report back what I see/find. Thanks again.

    Sincerely,
    Rich
     
  10. zook

    zook Friend of Leo's

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    If you can safely check the voltages that will give you an idea of what is wrong.
     
  11. MadJack

    MadJack Friend of Leo's Silver Supporter

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    Most of the time the issue is with tubes. Just because the tubes glow only means the heaters in them are working. You say it's a year or two old, so the power tube are a definite possibility. It could be one of the preamp tubes or the phase inverter tube.

    Another possibility is the pins are loose in the socket. The sockets can be tightened with a small jeweler's screwdriver. (With amp off an unplugged, of course!)
     
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