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Replacement 12AX7?

Discussion in 'Amps and Cabs [BG]' started by Sonorous, May 13, 2006.

  1. Sonorous


    Oct 1, 2003
    Denton, TX
    What are some good 12AX7s to put into my recently acquired used SWR SM-400s? It's currently got a Groove Tubes in it, and while I don't know how old it is, I have noticed something distorts for a few minutes every once in a while and then goes away. I'd like to replace the tube to see if this helps at all.

    So what are some different characteristics of different types of 12AX7s? (I'm not really sure what I'm looking for because I don't know what tubes do to the sound, I'd like to hear some descriptions first and then pick) Do preamp tubes really have anything to do with the sound at all, or should I just try to find the cleanest one?

    What about a good place to order them from?
  2. RevGroove

    RevGroove Commercial User

    Jul 21, 2002
    Burlington ON Canada
    Manager, Account Services: Long & McQuade Ltd. (Burlington); MTD Kingston Basses International Emerging Artist; Bartolini Electronics Emerging Artist
    Can't say enough good things about the ECC83S I put in my hybrid head, great low end, nice overdrive, can't ask for more!
  3. Groundloop


    Jun 21, 2005
    "I have noticed something distorts for a few minutes every once in a while and then goes away"

    Yikes!! My advice. Get thee to a tech pronto. I'm by no means a tube expert, but in my experience being around amps, if a tube is problematic, it's always a problem, the problem doesn't come and go as you describe.

    The SM400S originally shipped w/ Groove Tubes in them, so there's a chance that yours has the original tube. But, there might not be any reason to replace it. There's a lot of conflicting opinion about preamp tube life. Some people retube every few years with "regular" use, some people say replace it when the tube gets microphonic. I've got a Trace Elliot RAH300SMX that's about to celebrate it's 10th birthday, and it still has the original Trace branded tube in it. No problems.

    Since all my bandmates cancelled our jam tomorrow, I'm going to take the time to swap the tube in my Yorkville XS800. I've bought both a JJ/Tesla ECC83S (which in the Yorkie is supposed to take some of the edge off the TubeDrive circuit, and in general make the whole thing fuller and warmer), and an Electro Harmonix 12AX7 because, well, just because. If it doesn't work in the Yorkie, I'll find a home for it somewhere. I should have some opinions to post tomorrow, but they won't be specific to your SM400, but they might be helpful.

    In the meantime, check out http://www.tubedepot.com/

  4. Kenny Allyn

    Kenny Allyn

    Mar 25, 2006
    The "Telefunken" ... is THE one you want, but they are really rare and hard to get ... I have some in a Ampeg guitar amp, made a dramatic difference.

    this is a good alternative

  5. Steve


    Aug 10, 2001
    The SWR stuff I have are some of the most tube sensitive front ends I've encountered. Telefunken is definatly the name that worked for me.

    They're not all that hard to find but thay dang sure ain't cheap. $50+
  6. Sonorous


    Oct 1, 2003
    Denton, TX
    How much of a difference is there between the ECC83s and the Telefunken? Is it worth the extra money, or is the ECC83s close enough to make the extra $40+ better off in my bank account?

    Thanks for the tube suggestions everyone, and thanks for the advice Groundloop. I think I'll end up spending the $10 on the JJ/Tesla and if I still get distortion then I'll see a tech. SWR has had awful repair service for a while, and I'd like to avoid it if possible.
  7. paulraphael


    Apr 13, 2006
    If you heard me play, you'd stop reading what I write.
  8. Groundloop


    Jun 21, 2005
  9. Planet Boulder

    Planet Boulder Hey, this is a private residence...man

    Nov 10, 2001
    6,482 feet above sea level
    I once had impure thoughts. Oh, and I pluck my ear hair.
    SMASH has done EXTENSIVE tube testing and he helped me pick some tubes in the past. I recommend PMing him...
  10. EricF

    EricF Habitual User

    Sep 26, 2005
    Pasadena, CA
  11. Phantasm

    Phantasm I Still Haven't Found What I'm Looking For.

    Sep 16, 2002
    New Orleans, LA
    Call Butch at www.bayoucables.com and ask him about preamp tubes. Butch is a bass player himself and has some great suggestions!
  12. paulraphael


    Apr 13, 2006
    If you heard me play, you'd stop reading what I write.
    anyone with too much currency loading them down should try some amperex tubes. i borrowed a pair of the 12au7s from a friend for my stereo. they were actually too tubey for my tastes ... huge, blossoming low end, thick, harmonically rich mids, and a rounded top. great for some music, but too thick and syruppy in general.

    good news that i didn't like them ... a matched pair usually goes for over $150. but i'm thinking they might be just the thing for bass, if you like an uber-vintage sound.

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