Dismiss Notice

Psst... Ready to join TalkBass and start posting, make new friends, sell your gear, and more?  Register your free account in 30 seconds.

SWR preamp tube replacement

Discussion in 'Amps and Cabs [BG]' started by brock29609, May 12, 2004.


  1. brock29609

    brock29609 4 strings, 2 wheels

    May 11, 2003
    Greenville, SC
    Based on recommendations I've read in old threads, I bought an Electro-Harmonix replacement tube for my SWR 550X (12AX7EH). However, I prefer the tone of the original tube (which is damaged). Anyone know what the stock 12AX7A tube is, and where I could find an exact replacement?
     
  2. Weren't they using Rubys?
     
  3. tornadobass

    tornadobass Supporting Member

    Nov 20, 2000
    Iowa City, Iowa
    Endorsing Artist: Black Diamond & SuperSensitive strings
    I think they were Groove Tubes...which means it could be several different tubes with the GT label.

    I like JJ/Tesla ECC83 in my SWR SM-400 amps.
     
  4. brock29609

    brock29609 4 strings, 2 wheels

    May 11, 2003
    Greenville, SC
    The original tube in mine has no markings. That's why I ask.
     
  5. How do you know when to replace a tube?
     
  6. Finger Blister, could you give some preliminary hints to how this tube sounds. I have a sovtek 12ax7lps in my SWR Bass750 right now, and it's good, but I somehow feel it could be better. Please relate your thoughts on the GT 12ax7m

    Thanks :)
     
  7. brock29609

    brock29609 4 strings, 2 wheels

    May 11, 2003
    Greenville, SC
    My head is a 550x, which only came out in the last year, right? I believe the original owner bought the head about 7 months ago.
     
  8. gbenner

    gbenner

    May 20, 2001
    ocean, new jersey
    "How do you know when to replace a tube?"

    Big Ben, preamp tubes last a lifetime, or so. I sold an old Fender Bassman 50W amp from the 60's about a year ago. The preamp tubes were still going strong. You'll change pre tubes for a different sound before one will fail. Now power tubes are a different story.

    George
     
  9. Did you know that the GT 12AX7M is a Chinese tube? Check out the pics here. That doesn't mean it will sound bad; they've been making good KT88's for close to a decade now. I also strongly disagree that all Chinese and Russian preamp tubes suck. With any tube, it depends heavily on the application. BTW, you can get the same 12AX7M from Ruby for half the price of the orange painted one and Ruby has the same six month warranty, and IMNSHO, screens their stock MUCH better than Hype, I mean Groove Tubes.
     
  10. Thanks FB, I'll look forward to it.

    Psycho, whats the "name" of the Ruby equivalent of the GT 12AX7M? If it's half the price, I wanna get one of those instead. Btw. whats your take on the 12AX7M (soundwise)?
     
  11. I doubt it's called the 12AX7M. It's probably the 12AX7 referred to above. There are two new Chinese 12AX7's listed in their catalog. I have yet to try one, haven't bought a 12AX7 in three or four years, but I've never really cared for Mullards in bass amps anyway.
     
  12. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    I bought a whole bunch of gear off Jack Read including a replacement tube for my SWR GP. We were going to put a GE 5-star 6201 in but his last ones of those had noise problems so he sent me a NOS triple mica 5751 which sounds great! In Jack's own words "rich, smooth and clear". Talk about making the GP sound seriously big and fat, instead of the somewhat brash growl it had before.

    Alex
     
  13. secretdonkey

    secretdonkey

    Oct 9, 2002
    Austin, TX
    I decided to try a 12AX7-M -- I liked what FB had to say about them. I only had a few moments yesterday to pop it in and test it out, but so far -- very good. Definite change in the character of the amp - seems punchier and "tubey-er", with the high end tamed just a tiny tad and given more character, which it really needed, IMO.

    Got a gig tonight and Friday to really decide. FB, I'll PM you with further impressions after that, but so far the "M" looks like a big winner.

    :)
     
  14. brock29609

    brock29609 4 strings, 2 wheels

    May 11, 2003
    Greenville, SC
    I compared my stock tube to photos on the internet, and it looks like my SWR came with a Tesla (JJ) 12AX7. Mine doesn't have the markings on the outside of the glass, but the guts are identical.
     
  15. tornadobass

    tornadobass Supporting Member

    Nov 20, 2000
    Iowa City, Iowa
    Endorsing Artist: Black Diamond & SuperSensitive strings
    Is that actually the JJ ECC83? That's what's in my SM-400S and it has a good combination of full tone, punch, and clarity. Groove Tubes relabels those and you can buy them with the JJ label as well.
     
  16. PM me too :hyper: (...or post your impressions here)
     
  17. Maybe is, maybe not. Following Lord Valve's raves for the last few years, it seems there is variation from year to year and even lot to lot in new production tubes. I recommend buying from a reputable dealer who tests the tubes before sales. I've found the following to have both good reputations and service:
    http://www.nebsnow.com/LordValve
    http://www.kcanostubes.com/

    Other folks probably have their favorites as well.
     
  18. brock29609

    brock29609 4 strings, 2 wheels

    May 11, 2003
    Greenville, SC
    yes.

    I ordered one from electron-valve.com. Anyone delt with them? From their website...

    All of our tubes are guaranteed to perform as described. We fully test each and every tube to ensure this reliability. The warranty for NOS (New) tubes is 90 days from date of purchase. Used tubes have a warranty of 45 days from date of purchase. If your tube fails and is within these warranty periods, we will replace, refund or credit your account, depending on current stock.
     
  19. That's by no means a definitive answer. Notice:
    Sounds like someone doesn't want to make a firm commitment to EITHER position. Who is this "Myles S. Rose" anyway?