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Terrible tube replacement story!

Discussion in 'Amps and Cabs [BG]' started by Davidoc, Jun 23, 2003.

  1. My SVP-pro preamp has been buzzing, and after taking it into the shop a while ago under warranty, they removed alot of the buzz. I ordered a set of replacement tubes from lord valve (4 chinese NOS ax7s and a AU7.

    I put in the new tubes. The sound is a bit different, I can't say wheather I like it better or less, but the sound is definitely different. The buzz is as loud as ever! Also, I open it up to check stuff out inside, and the AU7 in slot 4 is burning hot and CRACKED. That's right, cracked. Two pieces instead of one. (this is after a few minutes worth of playing. I take it out carfully, and just replace it with the ax7 that was in there before (dumb tech people replaced it with the wrong type hoping I wouldn't notice.)

    Anyways, so now I guess I have two choices of tubes, and I'm stuck with the AX7 that was in there before in slot 4 instead of a proper AU7.

    Both cases leave me with just as much buzz as before (although the buzz tone is different with the new tubes, but it's at the same volume. This sucks dick.
  2. Schwinn


    Dec 4, 2002
    Sarasota, FL
    Wow Davy...you've had the worst luck with your amp! Even though I like my SVP, if I were you and had the problems you've had, I would ditch that thing! Seriously, it's not worth the trouble when there are other preamps out there.

    By the way...I solved my noise issue by keeping the master only halfway. It's only noisy when the master and gain are turned up too high together. But you've probably already tried that...anyway, good luck searching for a new preamp!
  3. There's gotta be something wrong in your amp's power supply, or some other major problem. Even the crappiest of tubes oughta hold up better than that, that's a PREAMP tube for gawd's sake. Not meaning to dis your tech...well I guess I am dissing him...something major is wrong. Take it somewhere else before you fry something else...Also see if you can talk to Psycho Bass Guy or Throbbinut here in this forum, they're more qualified than I.
  4. Paul A

    Paul A

    Dec 13, 1999
    Hertfordshire U.K!
    To be honest, suspect the tubes.
    Chinese tubes are only any good as lightbulbs.
    Get some decent tubes in there!
    Sovteks or JJ's should do the trick!

    Oh BTW The "Buzzing" fault is most likely to be with the filter capacitors on the main power supply.
  5. Thanks for the input guys!

    This isn't so bad after all. The cracked AU7 (which was actually an exception-not chinese, a phillips) is easy replaced with one of the AX7s that was originally in the preamp. This in combinaion with the naturally higher gain of these tubes allows me to cut the poweramp, yet retain the same volume level. When the poweramp gain is cut, less buzz comes from the preamp into the speakers. Overall, I guess this has improved the buzz situation.