Amp whining?

Discussion in 'Amp Central Station' started by ComingApart, Sep 10, 2004.

  1. ComingApart

    ComingApart Tele-Meister

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    Hey guys, my SF Twin has developed a noticeable whine to it. It doesn't change with volume or reverb level, or anything like that.
    All the tubes are tight in their sockets.
    It's sounds sorta like that alternator interference whine you'll get on a poorly grounded car audio system.

    Any ideas guys?
     
  2. simonc

    simonc Friend of Leo's

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    Re Amp Whining

    Yeah I hear a Whining With my amps too, usually if Im thinkn of gettin a new one any my girlfriend is sayn...do you really need that amp? its so expensive etc etc.... ;)


    but seriously, you might want to check out the transformers, sounds to me like maybe a winding is slightly loose and vibrating, this can cause a whining sound, i havent had this experience from a guitar amplifier though, actually from a 20 year old tv set.
     
  3. jjmantele

    jjmantele Tele-Holic

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    Could be parasitic oscillation or a microphonic tube. Try it with the pre-amp tube(s) pulled out. Start from the right and try pulling out one at a time. Put on standby when pulling. Power tubes get very hot. When it stops, it has something to do with that stage. Then try a "new" tube in that socket. If it is still there it's not the tube.

    However, if you have a master volume (that's working properly) and the problem occurs with it turned all the way down, the problem is not in the pre-amps. Same with the reverb knob/circuit.

    You can also tap on the tubes glass with the eraser end of a pencil and listen for noise thru the speaker. MV knob would need to be "on" for testing the "small" tubes here. If one tube offends it may be the culprit. I've had fairly new power tubes and preamp tubes that were microphonic. The tap test isolated them.

    Also try other wall outlets in the house to rule out interference.
     
  4. jumpnblues

    jumpnblues Friend of Leo's

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    Amp Whining...

    ...check the batteries in any pedals you're using. Low batteries in some pedals will sound exactly as you describe. It's a cheap fix if that's the problem. 8)
     
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