tube Question

Discussion in 'Amps and Cabs [BG]' started by seansbrew, Oct 16, 2001.

  1. seansbrew

    seansbrew Supporting Member

    Oct 23, 2000
    Mesa AZ.
    I am looking for a replacement tube for my SM-500 head.The head has one 12ax7 in the pre-amp. I was wondering if anyone has experience whith NOS tubes,like Telefunken,Mullard etc?I have the Chinese made tube right now.
  2. Tapp


    Aug 29, 2001
    USA, Mississippi
    As far as tubes go: The Telefunken and Mullard are usually the cream of the 12AX7 crop with RCA following shortly behind. You have your Amperex and Brimars in the same league but they're rare.

    Now, when you apply this knowledge in context with a certain design, it's not so easy to say who sounds best. Some modern manufacturers (Mesa being one) design they're gear around the "limitations" of Chinese tubes and these can actually sound better in these situations. I do not know the goals of SWR. I recommend using your ears and not a pre-conceived notion that a certain tube must certainly sound better.

    I hope I helped a little.

  3. VicDamone


    Jun 25, 2000
    The volume 8 number 2 issue of bass frontiers (Chuck Rainey on the cover) has an interesting artical by Kurt Kurosawa. In the end he picks the Sylvania JHS 5751 also tagged 5751WA, JG 5751 which comes in a white government contract box.

    To further complicate your selection simply going by the numbers is not enough. You have to match the construction of the bottle to determin its origin.

    If you find any of these Majic tubes let us know were to get'um.
  4. VicDamone


    Jun 25, 2000
    So Donne...where can I get a couple?
  5. I have the Eden Navigator preamp that came with a Sovtek 12AX7WA. So, believing that this tube was average, I set out to find superior tone. I have a Mullard(Original), bought a Telefunken, Jan phillips, NOS G.E.7025, RCA 12AX7A,Sylvania ECC83/7025,and a Sovtek 12AX7WB.

    The Jan and Sylvania sounded the most solid next to the original Sovtek WA. The Sovteks come in a lot of amps now, and I believe that amps are now being voiced around this tube.

    Opinion: Mullard, Tele, EH, Amperex are more for the high gain you would want for guitar, not bass. For me, I want a solid, LOW gain, clean tube with full sound.
    I am using the Sovtek 12AX7WA in all my preamp applications now, even my vintage stuff.

    They cost about $10.
  6. boogiebass


    Aug 16, 2000
    Interesting observations about the Sovtek, Bob. Not sure all the tubes you cite are "more for the high gain you would want for guitar" but I think you may be onto something here. Thanks.
  7. CS


    Dec 11, 1999
    Groove Tubes have a number system to determine gain. I have to be careful here but all they really do is match and grade Sovtex and i think JJ or Svet valves and badge them up. I have used GTs in guitar amps and they are comparable to Sovteks.

    ECC83's as us Brits call them are widely available and used in many amps. Directly comparing Sovtek WXT's to some old Mullards I had in a dead amp the Mullards are lower gain.

    The advantage of this application is that there is only one ECC83 (whatever) whereas I have 5 in the Vox and 3 in the Trace Elliot (I dont even know whats in the Trace).

    Try for a list of NOS v modern valves and a detailed comparison test (albeit with guitar) of ECC83's (and others).

    I would try a few valves. BTW I recently gave some preamp valves to a guitarist mate who had Chinese OE valves in his Laney. We put two high gain Sovteks in the lead channel and a Mullard in the clean one. THe lead channel did improve but the clean channel was greatly improved. It was no longer harsh and seemed purer.

    Anyway at some point you are going o have to bite the wallet and buy some valves.
  8. Chasarms

    Chasarms Casual Observer

    May 24, 2001
    Saint Louis, MO USA
    I see NOS 12ax7s all the time on ebay. Sometimes the boards are so saturated with them you can get a great deal.

    Personally, I haven't found the single-tube preamps in hybrids to be significantly affected by the choice of tube. The differences are fairly subtle. Although there is a more noticable difference in the multi-tube preamps.

    Other than that, I would suggest trial and error. The beauty of a tube lies in its imperfections. So you can get five tubes from the same maker and they will sound different. Just try them til you are happy.
  9. Please excuse me, I should have been clearer.
    It has been a while, but the Sylvania and Jan Phillips were low gain. The NOS stuff was maybe slightly higher, and the Mullard & Telefunken were higher or went into clip easier.

    I would also like to note that I hear a lot of "Tube sound and quality" language is directed toward GUITAR amp sounds, not necesarily the associated frequency range of bass, and sounds that are desirable for bass.