Weird Issue w/ Noise - Polarity Problem?

Discussion in 'Amp Tech Center' started by stephent2, Jul 10, 2020.

  1. stephent2

    stephent2 Poster Extraordinaire

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    So I have one amp, a custom built unit based on a 5F11 that has something strange going on. Plugged straight into the amp, when I turn the volume knob on my guitar up and down, coming through the amp, it sounds like a dirty volume pot!!

    Guitar plugged through any other amp I have, doesn't do it,.. so I'm sure it's the amp and any guitar that I plug in, same issue,.. turn the guitar's volume up and down, sounds like a dirty volume pot on the guitar. Plugged into two other amps I have, no problem.

    Any ideas? oh,.. all new tubes.
     
  2. Gardo

    Gardo Tele-Holic

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    I had a problem with static when my fingers moved across a tele pickgaurd ,a wipe with a dryer sheet was a quick temp fix. But in the amp ? ,that's a strange one.
     
  3. schmee

    schmee Doctor of Teleocity Silver Supporter

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    It can be a sign of some other things going on. Sometimes scratchy pots on the amp are not pot problems at all, but stray electrical stuff inside the amp showing up when you turn the pot.

    If it's static as Gardo mentions, you need to shield and ground the guitar properly. But it should do it in other amps also then.
     
  4. stephent2

    stephent2 Poster Extraordinaire

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    as I mentioned, any guitar (mine are very well shielded) into this one amp will give the same results, same gtr into my other amps, no issues. So, it's not the guitar, it's the amp. And the strange part is, turn the volume knob on the gtr, it sounds like it's a dirty guitar pot, but the issues is the amp. I'm guessing has to do w/ a ground or polarity issue.

     
  5. D'tar

    D'tar Friend of Leo's

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    Did you build it? You may have DC voltage on your inputs which is not a good thing! Do you have a multimeter. you can check by clipping the leads, red to tip and black to sleeve, on one end of a guitar cable. do not use hands to hold the clips on. Then turn on the amp and plug the other end of the cable into the input. have your meter set to read dc voltage. start with the highest setting and work toward the lowest setting on the meter if not auto ranging.
     
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