Twin Reverb RI Humming - Preamp Tube Question

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by awaywardson, Oct 3, 2008.

  1. awaywardson

    awaywardson Member

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    TRRI hums, with all controls on 0 and nothing plugged into the input jacks. Hum volume increases as amp volume knob is turned up. Very annoying. Bought this here on TGP and it just came it today.

    I did a search and i see that i could get past this by some preamp tube changes. Can I use JJ ECC83S or ECC81 in place of the 12AX_7?? Have some of these from my HRDx...

    I plugged in and while playing the hum is of course covered up by my guitar, but in a band situation where i'll be mic'd and we break in a song, i don't want "hummmmmm" coming from my side of the stage..

    what to do, what to do?

    ALSO - the HRDx had that page run by Justin Holton, or something like that. Does the Twin Reverb RI have such a page??
     
  2. awaywardson

    awaywardson Member

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  3. Dave C

    Dave C Gold Supporting Member

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    ECC83 is a 12AX7 , ECC81 is a 12AT7. Either one can be subbed in for a 12AX7 with the 81/AT7 having slightly lower gain .
     
  4. phsyconoodler

    phsyconoodler Member

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    It sounds like a couple of your power tubes may be way out.You need to have all the tubes and bias checked.If it's a preamp tube,which seems unlikely,you may find it by swapping tubes around.
    I'm betting it's a power tube issue.
     
  5. awaywardson

    awaywardson Member

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    swapped some tubes around, but noticed a loud "POP" when I put the amp on standby. still hums...
     
  6. MACWHISPER

    MACWHISPER Member

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    Have you tried doing a hum adjust on it? Check Fender user guide for instructions.
     
  7. awaywardson

    awaywardson Member

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    i swear i've never heard of such a thing. am i missing something in the user's manual??? :huh

    and right now i'm just living with it. not as noticeable when i'm gigging, but at home it seems to be more noticeable. and i've checked my outlets, my house is properly grounded. but for the moment, like i said i'm not gonna deal with it - too many other problems in my life to worry about some hum.
     
  8. slider313

    slider313 Silver Supporting Member

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    Sounds like mis-matched power tubes to me also. If they were a matched quad, one may have drifted far from the other three.
     

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