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Carvin BX500 Pre Amp Tube

Discussion in 'Amps and Cabs [BG]' started by lukelogandennis, Dec 18, 2012.

  1. When the preamp tube is engaged I'm not getting a single sound from my amp. However, when the tube is bypassed everything sounds normal. Is the tube dead? Do I need to just replace it? Or is there a bigger problem?

  2. FunkHead

    FunkHead Supporting Member

    Mar 10, 2007
    Phillipsburg, NJ
    The tube is the first thing I would try. They are cheap. It's just a 12ax7. Just pop the screws out of the top cover and remove it. The tube pulls out and just push in the new one.Very slight wiggling is okay side to side.
  3. lhoward


    Apr 27, 2003
    Western NY State
    Is it still under warranty? If it is, you might want to contact Carvin first and follow their recommendations. If they suggest testing the tube, then I'd pull it and take it to a reputable electronics shop that can test it to see if its the problem or not. The alternative is to buy a new tube (they're not that expensive) and put it in. If that doesn't fix it, then its time to contact Carvin again.

    Lloyd Howard
  4. MontanaBassDude


    Sep 20, 2011
    The other alternative is to not even worry about it. Ever. Take it from me and dozens of others, there isn't one whit of audio difference made by that 12AX7. Nothing. :meh: Run without it; one less thing to go wrong during a gig.
  5. RNV


    Apr 13, 2010
    Loxahatchee, Fl
    fEARful (I endorse them, not visa versa)
    My BX1500 pooped the bed after I got it with the same issue. Carvin replaced the intire amp under warranty.
  6. Passinwind

    Passinwind I Know Nothing Supporting Member Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Mine (Rev C) wouldn't work at all without a tube in it, bypassed or not. Later ones are not like that though.
  7. chucko58


    Jan 17, 2002
    Silicon Valley, CA, USA
    I paid for all my gear myself. Well, me and MasterCard.
    The tube is connected to the preamp board by a ribbon cable. There is a good chance the ribbon cable connectors need cleaning.

    Of course, the tube itself could be dead, but cleaning the connectors costs only a few cents' worth of contact cleaner, so it's worth trying first.