1. Please take 30 seconds to register your free account to remove most ads, post topics, make friends, earn reward points at our store, and more!  

Tube recommendation for SVT-II?

Discussion in 'Amps and Cabs [BG]' started by Whoopysnorp, Sep 9, 2008.

  1. Whoopysnorp


    Feb 5, 2006
    I've had a sextet of Svetlana 6550s in my SVT-II for about four years now. They haven't seen real heavy use--regular rehearsal use for probably 2-3 of those years, and maybe about 15-20 gigs total--but I'm getting pretty weak volume now. I have to turn it up past halfway to get it even kind of loud (through an SVT410HLF cab), and they are breaking up about halfway up the dial (that part could be normal I guess). Seems like they should have lasted longer, but I get the impression these are budget 6550s. Does anybody have any recommendations for power tubes for these amps? Current production, please, unless you can find a NOS tube that sells for ~$200 a sextet.
  2. Whoopysnorp


    Feb 5, 2006
    Forgot to mention that I've been running it sitting on its side next to the cab on the advice of the previous owner, who said it would always blow fuses when he had it sitting on top of his 8x10 (presumably due to vibrations). He played it loud, though, and surely my 4x10 won't rattle the amp quite so much, so I'm planning to have it on top of the cab in the future. However, is there any way this could have increased wear on the tubes?

    There have also been a few occasions where it was switched on and taken off standby without a load connected, due to a third party removing the speaker cable without telling me. I always made sure to switch it back to standby and correct the problem immediately, and my impression was that output transformer damage due to this kind of use would just kill the amp entirely, but is there any way my volume drop could be due to an OT problem?
  3. You need a rebias, not new tubes.
  4. It is possible that a strong enough vibration could interrupt the relatively low voltage of the bias, either at the base/socket connection or in a cold solder joint, and put the amp into momentary runaway, blowing the fuse. Just get some foam or use a couple of folded bath towels between your amp and cab. There's no excuse to take the chance of damage with solutions that easy and cheap.

    Unless you were playing through it at the time, there was no danger.
  5. Whoopysnorp


    Feb 5, 2006
    On occasions where this happened, I actually tried to play a couple of notes through it before realizing what was going on.

    I would love it if this turned out to be the case! I have the means to bias amps, so I can give this a try. When I retubed it last, I had the shop bias it, and I don't really know how they set it.

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.