Loud buzz coming out of my cab

Discussion in 'Amps [BG]' started by mikechenko, Nov 13, 2013.


  1. mikechenko

    mikechenko

    Joined:
    Nov 25, 2012
    Hey everybody, I have a 70's era Fender Bassman 70 head that I have set up with a 15 inch Carvin cab. I let the head warm up a bit plug in and play and after about 5 mins I get a loud buzzing sound that comes out. Not a feedback noise, just a loud buzz that no matter what setting the volume is at, its always louder. Turn off the standby switch and goes silent, wait a few minutes, turn it back on and I'll play and it'll do it again. Any ideas?? Thanks in advance for any feedback.
  2. B-string

    B-string Supporting Member

    Joined:
    Nov 21, 2008
    Location:
    Lake Havasu City, Az USA
    1) Power supply filter caps too old and need to be replaced. 2) An output tube that is failing (if "red plating" this is very dangerous to the amp head).
    Have that amp head looked at by a good tube amp tech NOW before you have expensive damage and a dead amp.
  3. mikechenko

    mikechenko

    Joined:
    Nov 25, 2012
    Thanks! This head was given to me, for free, and has worked great for a year. Never dealing with tube amps before, how much, ballpark, would replacing tubes cost and general maintence on an older piece of equipment run?
  4. B-string

    B-string Supporting Member

    Joined:
    Nov 21, 2008
    Location:
    Lake Havasu City, Az USA
    Well first, don't replace tubes that are not bad. You may have some vintage tubes that are still fully serviceable and should be kept in the amp.
    Pay for a bench fee to have it checked (usually between $50 to $75) that will find what is wrong, general maintenance and what is needed instead of just throwing money away. Figure a total re-cap on it will be around $200 or less. Tube prices vary a lot depending on brand so find out what is needed first.
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  6. BassmanPaul

    BassmanPaul Gold Supporting Member

    Joined:
    Aug 25, 2007
    Location:
    Toronto Ontario Canada
    +1 If you look at your output tubes when the Hum is present see if one or both of the plates are showing red hot. This is not the heater at the centre of the tube's structure but rather the grey metal forming at the outside.
  7. The comments here are directed at your amp but your OP says the buzz is from your cab. If from the cab, I've had one where one of the internal braces came unglued and made a horrible buzz. I just added some glue and a few well-placed screws and that solved that. Is your buzz from the cab or the head?
  8. nashvillebill

    nashvillebill

    Joined:
    Oct 13, 2002
    Location:
    Nashville TN
    We're addressing the amp because the OP said "no matter what setting the volume is at" so we are assuming he doesn't mean a vibration-related buzz.
  9. B-string

    B-string Supporting Member

    Joined:
    Nov 21, 2008
    Location:
    Lake Havasu City, Az USA
    Unless the cab also buzzes when the amp is off? The OP did state it stopped when in standby so the cab is only reproducing what is sent to it.
  10. B-string

    B-string Supporting Member

    Joined:
    Nov 21, 2008
    Location:
    Lake Havasu City, Az USA
    Not a cab problem :)

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