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12AX7 / 7025 preamp tubes...which are best?

Discussion in 'Amps and Cabs [BG]' started by Mad Subwoofer, Apr 30, 2002.


  1. I want to swap my preamp tubes in my Mesa M-2000. there are so many to choose from...Chinese, Russian, NOS, Yugoslavian...EH, GT; which ones for deep, rich detailed tone?
    Thanks!
     
  2. VicDamone

    VicDamone

    Jun 25, 2000
    My favorite so far has been the Sylvania Gold Brand 5751 with three grey mica plates. I'm still looking for a Sylvania JHS 5751.
     
  3. In the same thread, whats a good high gain, noisy 12X7? I only use the tube channel of my preamp for distortion and want something more, umm..., screeching than the tube that is in there.
     
  4. RedGrange

    RedGrange

    Jun 11, 2000
    Springfield, IL
  5. That link looks very useful , thanks. I need a tube that will make my preamp larger and "deeper" sounding...totally subjective I know.
    VicDamone; why do you prefer those tubes and what did you replace? What was the difference in sound for you?
     
  6. lneal

    lneal

    Apr 12, 2002
    Lee County, Alabama
    FYI:

    The 5751 is an industrial version of the 12AX7A. It has a high shock rating (600 G's!!) and low noise. It also has less gain (lower output) than the 12AX7A.

    The 7025 is a low noise version of the 12AX7A. It was designed for use in high fidelity audio circuits.

    This is according to the RCA receiving tube manual. I can't really offer much help on the new production tubes, but I do know my way around NOS tubes pretty good.
    Any good GE or RCA 12AX7A or 7025 should give you nice, fat tone. The JAN (military) versions are more durable. 7025's usually go for a little less $$ than 12AX7A's. Of course the holy grails of tone are the old Telefunken and Mullard tubes, but IMO they are overpriced and the difference is not really worth the extra dough.
    If I can be of further assistance, let me know!
     
  7. VicDamone

    VicDamone

    Jun 25, 2000
    I currently use an Eden Navigator preamp for its three balanced outputs. It's a flexable preamp tone wise but it's set flat ninty precent of the time. It came with an Eden branded 7025 which has a very smooth tube grind/overdriven tone. In fact I barely noticed it's effect while using the electric basses. It wasn't until I accidently had the tube blend turned up while using my Realist pickup/upright that I noticed the tube effect.
    After reading a very well done artical in Bass Frontiers volume 8 number 2 (Chuck Rainey cover) by Kurt Kurosawa, I decided some experimentation was in order. Using Kurts list I located a single 5751 Sylvania Gold Brand at a flea market. The difference in character between the 7025 and the 5751 is quite substantial. Much more dirty grind with more of a full body or bottom. They'er supposed to have less overall output than the 7025 or 12AX7 but I'm not hearing it.
     
  8. Hugh Jazz

    Hugh Jazz

    Sep 13, 2001
    Atlanta, GA
    I'd be very interested in these results.
     
  9. Well golly, that sounds just about right? Less gain I can handle...more "booty" I need, not volume. Grey plate, Sylvania Gold brand. $40 most places I've checked, but they are out there. That would be your suggestion?
    Here is that Kurosawa article I think; http://www.audioasylum.com/audio/tubes/messages/39285.html
    Thanks Vic. And Ineal.
     
  10. i've replaced the tube in my Hughes & kettner tubefactor overdrive pedal with a Russian Sovtek 12ax7 , and it sounds even better now than it sounds like with the standard tube ( can't remember the brand atm ), and the russian sovtek was only $ 15 over here.
     
  11. CS

    CS

    Dec 11, 1999
    UK
    The Sovtek EH's have more 'booty'
     
  12. Johnny BoomBoom

    Johnny BoomBoom Supporting Member

    Jun 8, 2001
    Glasgow, Scotland
    I've only ever had a 12AX& in my Marshall g**tar amp! I changed the stock Marshall valve for a Sovtek one - sounds very nice. The Sovtek valve was quite cheap at the time - £5 ($7) but that was about 6 years ago!
     
  13. lneal

    lneal

    Apr 12, 2002
    Lee County, Alabama
    Mad Subwoofer:
    The tube on the right is a Sylvania JAN (Joint Army-Navy) military version. Nice. It was probably made by Philips. The one on the left is a GE, even nicer, IMO. I think you could probably find some NOS if you look around, but at that price they would be worth having to experiment with. That seller is a good person to deal with, too.
     
  14. VicDamone

    VicDamone

    Jun 25, 2000
    Yeah, thats the Kurosawa artical, and those are 5751 tubes but I can't tell from the photo exactly what they are. I think Ineal has identified them correctly.

    In my search I ran into many of the JAN Sylvania's and bought a couple. They'll get you into the ballpark tone wise, the Gold Brand is only slightly fuller and more refined to my ears with my gear. Frankly, with tubes, results can vary somewhat due to the differences in preamp design etc.

    Keep in mind these 5751's are a more industrial or heavy duty tube. They sounded terrible in my Hi-Fi preamp.

    If anyone finds a stache of the tubes Kurosawa mentions in his artical let us know.
     
  15. I'm using EH tubes in my SVP-PRO and am pretty happy with the tone.
     
  16. TheLarch

    TheLarch Supporting Member

    I slapped some Electro-Harmonix replacement tubes into my Ampeg SVT-3Pro (4 x 12AX7 and 1 x 12AU7) about a year ago and I've been pretty happy with the results. The EH's are nicer than the Sovtek's that came standard. It's hard to quantify the sound change, but it seems as if there is extra warmth without being boomy.
     
  17. A tube afficianado guy has just told me that I'd best stick with a 12AX7 for my Mesa preamp because that is what it was designed to work best with? He said while the 5751's were good they offer only 70% of the gain and may not "jive" with the M-2000. I don't think It would be a problem but those tubes ain't comin' cheap.
    Thoughts...?
     
  18. lneal

    lneal

    Apr 12, 2002
    Lee County, Alabama
    Hey Mad Subwoofer:

    I almost forgot! I have used a Sovtek 12AX7LPS in my Trace pre and they are very nice! As I said, I don't know much about the current production tubes, but these were recommended by no less than Lord Valve. They have nice, long plates (better for bass IMO) and they are harmonically very nice. In spite of the good luck with the Sovtek, I am still leary of new tubes. So much re-branding and other things. The only reason I bought it was so I wouldn't ruin my good NOS'ers. Had to go back to my trusty old GE though! Try the Sovtek 12AX7LPS--you might like it too!
     
  19. Umm..God; so many choices, my head is starting to spin. So you recommend I go down to the store and try those Sovtek 12AX7LPS first. this may sound a little silly Ineal but could you give me a list 1-4 of which i should try?