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Attn: tube gurus. Can a tube socket itself become microphinic?

Discussion in 'Amps and Cabs [BG]' started by XtraLongScale, Jul 30, 2009.

  1. Jul 30, 2009 #1
    XtraLongScale

    XtraLongScale

    Oct 6, 2005
    Holyoke, MA
    The situation is this: I was testing a bunch of 12AX7s in my Peavey VB-2 to see if they're all operational (I don't own a tester and this was my only available option) and in the process, the overdrive channel became very hissy and microphonic. My immediate thought was the tube was bad, but when switching the tube the problem was still present and still the same after I put in yet another different tube. My clean channel, which I use exclusively works perfectly but I was really starting to dig my OD channel with my new tube of choice. Could all that tube rolling have disrupted something in the signal path? I always made sure the chassis was completely cooled down between carefully installing and removing the tubes, but I'm still a rookie when it comes to this kind of thing. No doubt I'll have to take it to a tech, but I'm hoping there's at least a slim chance that it's something I can fix at home and if not, I can at least learn why this came to be so I can avoid this situation in the future. Any and all input is greatly appreciated. Thanks.
     
  2. Jul 30, 2009 #2
    throbbinnut

    throbbinnut

    Jun 20, 2000
    georgia....georgia........geor
    It might be the socket, but odds are it's the solder joint from wire to socket terminal. If that's a bad solder joint, it could cause that.

    Whack the crap out of your amp and see if it makes a difference. Seriously. If it's a bad connection somewhere - even internal to a capacitor or resistor - a mechancial shock can make it worse or better. Then of course you fix the bad connection once you trace it down.

    Chris
     
  3. Jul 30, 2009 #3
    John Wentzien

    John Wentzien

    Jun 25, 2007
    Elberta, AL
    Artist:TC Electronic RH450 bass system (original test-pilot)
    Does the tube socket mount to a circuit-board?
     
  4. Jul 30, 2009 #4
    John Wentzien

    John Wentzien

    Jun 25, 2007
    Elberta, AL
    Artist:TC Electronic RH450 bass system (original test-pilot)
    Be careful fiddling around inside a tube amp...There is enough juice stored in the caps to kill you DEAD...Even if it's unplugged!
    Use a wooden chop-stick for poking around.
     
  5. Jul 30, 2009 #5
    XtraLongScale

    XtraLongScale

    Oct 6, 2005
    Holyoke, MA
    Touching the caps was definitely the furthest thing from my mind. I enjoy living too much to want to do that ;) Besides, the chassis' already back in the head enclosure and I'm too lazy to take it back out (that's the only way I can access V1 & V2 - no way to access them from the front = whattapain). So I gave 'er a couple "Irish kisses", as in a few good whacks and the OD channel's still plenty hissy but it's not microphonic anymore when I tap the chassis. As far as the sockets themselves, I think they're mounted directly to the chassis although I haven't taken a peek beneath in a while but that's one issue (board flex) I recall looking for when i initially got the head. I did some reading in the TB archives and read of caps going microphonic - another thing to consider.
     
  6. Jul 30, 2009 #6
    John Wentzien

    John Wentzien

    Jun 25, 2007
    Elberta, AL
    Artist:TC Electronic RH450 bass system (original test-pilot)
    My guess would be one of the connections to the tube socket,,,either a cold solder joint or a short.

    Especially if it started doing this right after you were changing the tubes.
     
  7. Jul 30, 2009 #7
    XtraLongScale

    XtraLongScale

    Oct 6, 2005
    Holyoke, MA
    Seems logical to me :cool: In any event I'll take it to a tech since I don't want to leave anything to chance. I can still gig with it fine on the clean channel but I can't wait to get that OD channel back in business. It sounded so good after the tube swap. Much obliged for the input.