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Fender '65 Twin Reverb Reissue - Noise Issues

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by leond, Aug 16, 2005.

  1. leond

    leond Member

    Messages:
    303
    Joined:
    Jan 4, 2002
    Location:
    Uxbridge, MA
    I recently took delivery of a one year old '65 Twin Reverb Reissue. The amp is in perfect condition and all stock (including the tubes). While the amp sound very good, there are two issues that I don't think are quite correct.

    1. With the foot pedal plugged in and the reverb on, the amp hums. If the pedal is unplugged, the hum stops. If the pedal is plugged in but the reverb is turned off (from the pedal), the hum stops. If the pedal is plugged in and the reverb is on and I touch the pedal, the hum stops.

    Could the problem be the pedal or the amp? The only other thing is that my house has crappy electricty (no grounds). Could it just be bad electricty?

    2. While I'm playing, it seems like if I play certain frequencies, I'll get a distorted sound (and not like good power tube distortion). Or almost like an electronic gurgling. It doesn't matter how loud I'm playing and the gurgling will sometimes continue after the note has died down.

    I tried tapping the preamp tubes and they made no noise. When I tapped the power tubes, I heard the gurgling noise. It was louder on one of the tubes than the other but they all made the noise.

    Is it time for new power tubes? Or is there something else wrong?

    Thanks for any help,
    LeonD
     
  2. unclej54

    unclej54 Guest

    your reverb hum sounds like a grounding problem. if it is it could be the input jack or inside the pedal or actually the cable itself. you might take the pedal cover off and visually check the wiring. see if there are any loose wires. check the solder connections closely and see if they are all bright and shiny. if the ground wire looks dull it could be a cold solder. if the cord has a molded tip it will be hard to check..if it unscrews you can check the wires there. if it's the input jack ground you'll have to decide if you're comfortable pokin' around in it.

    oops, i just saw the my house has no ground part..why don't you take it to someplace that is grounded and see if that corrects it before you do the above?

    as for the gurgling it does sound like you might want to replace the power tubes. if they've been played hard for a year they're about ready anyway.

    good luck.
     
  3. leond

    leond Member

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    Location:
    Uxbridge, MA
    Thanks for the replies guys.

    I pulled the bottom off the footswitch. Everything looked good under there. I'll take the switch to a store and try it in another Twin and see if that amp hums.

    I have an old set of 6L6s hanging around the house that I can put in and try. My guess was that it's the tubes. I've already started looking around for replacements and how to bias the amp.

    Thanks again,
    LeonD
     
  4. Blue Strat

    Blue Strat Member

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    Location:
    Sterling, VA (not far from Washington DC)
    What they said.

    To test the power tube situation, you can safely remove the supsected problem tube (and it's counterpart from the other pair on the opposite side of the 4 tubes, if you like) and try again.

    No harm will come of this (you'll have half the normal power output) and you'll know for sure whether or not that tube is a problem.
     
  5. leond

    leond Member

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    Location:
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    Is that the same as saying either the two outside tubes or the two inside tubes?


    The odd thing is the amp looks like it was never played (although I'm sure the outside condition of the amp is no indication of the condition of the tubes). And the fact that all the tubes make the noise when I tap them; one however is worse than the others.

    LeonD
     
  6. Blue Strat

    Blue Strat Member

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    Location:
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    Yes, 2 inside or 2 outside (though in reality, either one from the left side and either one from the outside would have the exact same effect).

    Concentrate on the worst tube. Tubes have been known to be defective or noisy right from the factory. Trust me.;)
     

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