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Hum from old echo unit

Discussion in 'Effects [BG]' started by BoognishMang, Feb 8, 2002.

  1. How do i get rid of the hum that come from my '64 echo chamber. I get a constant hum (never changes) no matter what bass I use ( jazz or stingray).

    I know I could go ahead a get a delay pedal, but love the warmth from this old thing.
  2. ...guess i'll have to try this one alone.
  3. Paul A

    Paul A

    Dec 13, 1999
    Hertfordshire U.K!
    If it's a Tube (Valve) unit it could be several things.
    Try changing out each tube for starters.
    If that doesn't help suspect the power supply filter caps.
    Check also that it's properly "Earthed".
    Was this unit supposed to be for an instrument or a Mic?
    If it was originally for a Mic, (Vocals) you might have impedance matching problems.
  4. Ok how confident are you in electronics?

    Many of the older equipment especially Fender amps from this period, were made with capacitors that weren't exactly the best. Replace any electrolytics you may see, also replace any 100k ohm resistors too.

    If it still hums, try replacing the last transistor in the circuit, or by placing a high value capacitor (say 22 picofarads) from the collector of the transistor to the base. That stops oscillations and RF feedback.



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