A Squealing PRRI

Discussion in 'Amps and Cabs' started by vashondan, Aug 15, 2018.

  1. vashondan

    vashondan Supporting Member

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    Of late my PRRI begins making a squealing noise. Doesn't start right at first and will come and go. What might be causing that? I've never had that happen with an amp before.
     
  2. ReddRanger

    ReddRanger Supporting Member

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    Microphonic preamp tube is my first guess.
     
  3. RJLII

    RJLII Member

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    I had a Blues DeVille that did that. Whistled like a tea kettle after being on for 15 minutes. Dealer was clueless. Called me everything but an honest man. They finally owned up to it and made it right. This was prior to me (and them apparently) having a clue about tubes.
     
    Last edited: Aug 15, 2018
  4. vashondan

    vashondan Supporting Member

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    Did it come that way or did it develop over time and they fixed it?
     
  5. vashondan

    vashondan Supporting Member

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    Is your warranty shot on an amp if you swap speakers?
     
  6. Blue Strat

    Blue Strat Member

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    Try tapping lightly on each preamp tube, one at a time, with the amp on and the volume up. If any cause a very noticeable ringing sound, that's probably your culprit.
     
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  7. Blue Strat

    Blue Strat Member

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    Not if you can swap back to the original speaker.
     
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  8. RJLII

    RJLII Member

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    I bought it new in ‘94. It was one of the first American made 4X10 versions. It started squealing right away. I was clueless, they were clueless. They made it right eventually.
     
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  9. vashondan

    vashondan Supporting Member

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    I’ll give it a try. Thanks.
     
  10. vashondan

    vashondan Supporting Member

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    @Blue Strat - Gave that a try, nada!

    Turned it on, turned it up, got a slight squeal for a couple of seconds and nothing after that. Left it on for 30 minutes. Tapped the tubes and no noise. Nevertheless, it's happened on more that one occasion. Hmmmmm?
     
  11. Blue Strat

    Blue Strat Member

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    Are you trying it with no guitar plugged in? If not, it could be microphonic pickups. If it happens again try unplugging the cable into the amp's input. If it goes away when you do that the problem is not the amp.
     
  12. vashondan

    vashondan Supporting Member

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    Good idea. It hasn’t been happening the last few days for some crazy reason. If (when) it starts again I’ll try that.
     
  13. Frosted Glass

    Frosted Glass Member

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    I retubed the preamp of my bassman with some NOS 12ax7s yesterday and had the same problem. A whistle - sort of like a feedback tone - that would come and go.

    I simply swapped V1 and V2 around and its gone.

    I think V1 is more sensitive to tubes with microphonic problems.
     
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