Amp vibration noise?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by khudson, Jul 28, 2005.

  1. khudson

    khudson Member

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    Aug 27, 2004
    Location:
    North Carolina
    I have a noise/vibration/rattle (?) that eminates from my Germino Masonette when I hit the lower frequencies. I have narrowed it down to one of the power tubes. When I pluck a low note, reach behind and hold that tube, the noise stops, but when I let go, it appears again. I have tried readjusting the tube to make sure it seated correctly. So far no luck. Is something loose? Is it the tube socket? How do I fix this annoyance that is ruining my tone?

    Also, I've noticed amp hiss louder than normal, even without any pedals connected - guitar straight into amp. Any suggestions to troubleshoot? Just a slightly microphonic pre-amp tube?

    Thanks...
     
  2. TheAmpNerd

    TheAmpNerd Member

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    I guess first is, it is a mechanical noise or coming
    through the speakers?

    If speakers, try different power tubes.
    OR, Swap tubes in scoket and see if it moves
    or stays the same. That will tell you something.
    Well be warned, pedals eat pre amp tubes.
    So if you damaged one, stick another one
    in and go. Too much drive/gain will do it
    from a pedal, I've had many a good tube
    ruined from jammers over driving the pre amp.

    Try that and let us know what you found out.
     
  3. Holden

    Holden Guest

    I've had this problem before as well and I've had some simple solutions that worked for me and might for you too. On my amp it was the wire tube holder making the vibration. I bent them slightly outward and away from the tube so that they wouldn't touch the side of the tube and rattle. Also if you have a head try putting a towel between the amp and cab to reduce the vibration. Both of these suggestions have worked for me in the past but also I have had to replace tubes because I couldn't stop the rattle any other way. Maybe you have already tried the two suggested tips but if not give it a shot!
     
  4. khudson

    khudson Member

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    Aug 27, 2004
    Location:
    North Carolina
    Thanks for the responses. I am thinking it is either tubes or chassis /cabinet vibration or both. On the masonette, there are no "wire cages" for the tubes. It is a 1x12 combo. The tubes just sit in the sockets. I think it is a loose grid plate on one of the power tubes. I contacted Greg and that is his first thought to check. I just don't have any backup 6v6's on hand at the moment. I have some new power tubes on order, so I will keep you posted. Also, I replaced the V1 pre-amp and the hiss was reduced. I had no idea that pedals eat them up like that, but it does make sense now that I think about it.
     
  5. unclej54

    unclej54 Guest

    when you said that it stops when you hold the tube it made me think that it could also be loose contacts in the tube socket..it's an easy fix if you know how to bleed the electrolytic caps..if not you stand a real good chance of frying yourself so you might want to get some help.
     
  6. khudson

    khudson Member

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    Aug 27, 2004
    Location:
    North Carolina
    After experimenting some more last night, I swapped the power tubes out w/ new JJ 6v6's. Much better. Still a little buzz and hiss present - swapped out the 1st pre-amp tube. Also, took off the lower back panel, which was slightly vibrating- aah, much better! I will put the panel back on when I get some foam strips. Basically, the pre-amp tube was microphonic and the power tube had a loose grid plate. Now the amp is sounding sweet again! I appreciate everyone's feedback. Thanks...
     

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