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Retube an SVT 3 Pro?

Discussion in 'Amps and Cabs [BG]' started by dbillow, Mar 28, 2006.


  1. dbillow

    dbillow

    Mar 28, 2006
    Raleigh, NC
    I just bought this amp for $450 on eBay.

    http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7400624128&rd=1&sspagename=STRK:MEWN:IT&rd=1

    I think I got a good deal but I am thinking that maybe I should just retube it from the git-go to start with as good a sound as I can get. This is my first tube amp. My questions are: how do I tell if the tubes are in need of replacing? What tubes do you recommend? is it hard to do myself (I'm fairly handy with basic electronics). What is bias adjustment and should I get a pro to do that for me?

    Thanks!:D
     
  2. chaosMK

    chaosMK

    May 26, 2005
    Albuquerque, NM
    Hi-fi into an old tube amp
    The SVT-3 has a tube preamp and a solid state power section. If it sounds like crap the moment you plug into it, you might have a burnt out tube, but that is unlikely because preamp tubes have a pretty long life. If you really dont like the sound of it from the get go, you could consider retubing. Also, preamp tubes will not need bias adjusting. Good luck with it!
     
  3. I JUST RETUBED MY PRO 3 AND IT MADE A WORLD OF DIFFERENCE COMPARED TO WHAT I WAS USED TO HEARING.
    AND ALSO I HAVE USED THIS AMP SINCE NEW FOR 5 YEARS
    BEFORE I RETUBED. NOTHING TO CHANGING THEM, JUST MAKE SHURE YOU PUT THE 12AU7 BACK IN THE SAME SOCKET THE ORIGINAL CAME OUT OF AND THINGS WILL BE FINE. BY THE WAY I REPLACED ALL WITH GROOVE TUBES ON THE 12AX7(4) AND A JJ ON THE 12AU7.
     
  4. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    Sort of....

    The power section actually has tubes for the drive, and SS only for the stage that drives the speaker..... all "gain" is tube in both pre and poweramp.

    So, there is some reason to consider changing the tubes in an older unit. Older meaning several years. If the unit seems to have low gain or low power, and it isn't due to EQ or tube drive settings, it might be a tube.

    But, preamp tubes in general last for years, and even the 12AU7 driver tube shouldn't "wear out" in a hurry.

    If you like trying different tubes, be my guest. That isn't a problem. The tubes in that unit need no biasing, as mentioned by a revious poster.
     
  5. dbillow

    dbillow

    Mar 28, 2006
    Raleigh, NC
    Thanks guys for all your input!
     
  6. Hawkeye

    Hawkeye Canuck Amateur

    I bought my III pro used so I just changed out all of the preamp tubes with Electro Harmonix. The amp definitely became quieter (less background hiss) than with the collection of one GT, some no-names etc. that were in the unit when I received it.

    The amp played cleaner and had less harsh break-up too. Try the EH's or maybe JJ's. You could always go with some Amperex, Telefunken, Mullard NOS for the 12AU7, but NOS 12AX7's are starting to get pretty expensive. I just went with premium new.
     
  7. interesting topic...
    i've been playing an svt proIII regularly since around 91-ish? i think(it was the style manufactured before the one shown in the ebay ad-with the block lettered logo)
    anyway, i have never replaced the tubes and i've never really had a comparison reference...it sounds like bass to me... but i wonder if i should be concerned about replacing the tubes just because they are getting old...i've been used to the way the amp sounds for so long, i'm wondering if i'd hear a dramatic difference in the sound, clarity, punch etc. if i replaced them?
    or is it a case of "if it ain't broke, don't fix it." ?
    interesting...

    thanks for reading this.
     
  8. flash99

    flash99

    Jun 8, 2005
    New York City
    I changed mine a few years ago and the sound did improve. I got mine in 1995 and it had all lower end Sovtec tubes (I think they ship with Groove Tubes now). A few years ago I changed all the 12AX7s to the military spec Groove Tubes (5751s maybe?) which run cleaner and I changed the 12AU7 to a basic Groove Tubes 12AU7. The sound got a little bigger and cleaner and I was able to drive the gain a little more without distorting.
     

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