Amp making strang noises...

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Barefoot, Feb 17, 2003.

  1. Barefoot

    Barefoot Senior Member

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    Have a newer (about 6 months old) tube amp. Last night I was noodling around and started hearing a ragged secondary tone coming from the amp. If I plucked the D string, 5th fret the proper tone would sound and also the ragged secondary tone. Only happened from a portion of the fret board. Its happened before with different strings/frets. and I believe different guitars.

    Later the amp started putting out a fairly loud steady tone of its own. Couldn't tell where it was coming from at first but I walked around and shut off all the electrical stuff I could and the tone was coming from the amp. Cycled the amp and all is well.

    This amp has made popping and snapping noises intermittently since I got it. It made one particularly loud snap/pop just after I got it and plugged it in for the first time.

    Don't think its from the guitar. This was my old standby SAS.

    Anyone care to speculate as to what the heck is going on?
    Thanks,

    Bob G.

    Also getting an intermittent buzzing. No floresent bulbs running.
    Will try the tube tapping discussed in earlier thread.

    No Ideas??
     
  2. Barefoot

    Barefoot Senior Member

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    Problems getting worse. Definately the amp. Ragged scratchy secondary tone with 3 different guitars and 3 different cables. Worse with the SC. Worse on low E string or D string between 9th and 12th fret.

    Bass tones are causing problems with the amp. Somebody said something about tapping the power tubes. Tapped the 2 power tubes and got the ragged tone. Looks like Vickie gets call tomorrow.

    Does this sound familiar to anyone? Maybe just bum tubes?
    Ideas appreciated.

    BG
     
  3. THLH

    THLH Member

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    Can you be more specific as to what the amp is? That would help me pinpoint the problem.

    As of now, I would first pull the preamp tubes to isolate the problem. Start with the driver (closest to the power tubes) as that will tell you if the problem is in the preamp or the power section. If you don't hear it after pulling the driver, it's in the preamp, and vice versa. Then try new tubes.

    It sounds more like you might have a bad cap somewhere. That ghost tone could be coming from a bad bypass cap. The pop you heard may have been it rupturing. Those are easy to replace. If you are getting hum, that may be a filter cap, which takes a little more $ and work.

    Get back to me.
     
  4. Barefoot

    Barefoot Senior Member

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    Thanks for the feedback. I was feeling a little lonely here.

    Its a Victori-ette with a factory speaker mod to 1-10" & 1-12". New within last 6 months.

    Been so busy at work haven't had the time to call Mark at V.

    The problem has some intermittent aspects to it as well. Its less of a problem w/brighter sounding guitars like a SAS w/artist and D1 pups. Base string on the SC cause more of a problem. On the SC 5th string problem is more note specific, say 7th to 9th fret.

    I'm sure its fixable but its a pain... Thanks for any imput..

    Bob G
     
  5. John Phillips

    John Phillips Member

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    It sounds extremely like a microphonic power tube to me - but you'd guessed that anyway, so I assumed you would have tried changing them by now...

    If it's not that it may be a loose connection somewhere - it's most likely to be caused by some form of mechanical resonance since it's frequency-specific.
     

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