Best 12AX7 for cleanest sound/optimum headroom

Discussion in 'Amps and Cabs [BG]' started by Cantstandsya, Aug 31, 2002.

  1. Cantstandsya


    Jul 27, 2001
    Fontana, CA
    The Sovtek 12AX7 in my SM400S seems to clip/distort too easily and is very muddy on the low end.Any suggestions?
  2. CS


    Dec 11, 1999
    The Sovtek 12AX7WXT was a very high gain valve. The WB is lower gain and not very impressive. I like the EH (BTW they are made by Sovtek). My favourite 12AX7 (or ECC83) is the Mullard. But they are expensive and I have no experience of them in your application.

    You are going to have to experiment

    You might want to PM this guy
  3. jokerjkny


    Jan 19, 2002
    NY / NJ / PA

    unless you've heard another SM400 that sounded tighter, it could just be the tone of the pre with your cab and bass. there are sooo many other factors besides the tube, tho a tube swap could be the magic pill.

    but if you're looking for a new tube, i've got some suggestions.

    btw, yea, the Sov's are known for their gainy tone. and i'm not a real fan of them in any amp, guitar or bass. same with EH's tho, they can be a bit better.

    IMHO, what you're looking for is a 5751. its a tougher spec'ed military version of the 12AX7. known to have high headroom, and 70% less gain. nice chimey highs, and great for slap. most 5751's are good from RCA, JAN Sylvania, JAN Philips, etc. its hard to find a bad brand due to the high military tolerances.

    another good one is a JAN Philips 12AX7. my fav tube for its good overall tone, and relatively cheap price. bright high end, tough and steely sounding mids, and good tight bass response. but, get 'em while they're hot cause i heard a shortage is looming.
  4. Chuck M

    Chuck M Supporting Member

    May 2, 2000
    San Antonio, Texas
    I've tried various tubes in SWR preamps and have settled on 1950's RCA blackplate 12AX7's as being the best sounding IMO.

    The Philips 12AX7 mentioned by Joker is actually a tube manufactured by Sylvania and I have seen the tube marked: Philips, Sylvania 12AX7(A, 7025), RCA 12AX7A (7025) and it was also sold by Groove Tubes as the 12AX7A. This tube sounds very nice (huge improvement over the Sovteks) and has nice definition in the highs and lows but does have a bit less clarity than the RCA blackplate that I prefer.\

    My experience with 5751's is that the gain is frequently higher than 12AX7's even though the spec calls for 70% of the gain of a 12AX7. The tone is less detailed and somewhat warmer sounding in the highs than most NOS 12AX7's. They sound good but are not my first choice.

    5751's would be a good choice if you want to tone down the overall brightness and detail in an SWR amp.

  5. I beleive that much of what you are hearing could be FET's clipping? I had a SM400 and never had a decent tone from it. I opened mine up and saw row after row of IC chips....I don't think that preamp design utilizes the tube much? I read that somewhere, I could be wrong of course.
    The WA's that Chuck mentioned are terrific in an SWR preamp, I like the EH's in my Mesa for their "snarl." I have a set of 5751 black plate, trip mica JHS that I will be trying soon as well. A set of Ei 12AX7's were less than impressive....
  6. KB


    Jan 13, 2000
    Chapel Hill, NC
    My favorites in my SM500 for the best sound to me are the Jan Philips 12AX7 and the Ei Elite 12AX7. However the 5751s do give a slightly cleaner sound, probably due to less gain.
    The Jan Philips 12AX7 was kind of rich sounding (what I like) and the Ei had more bottom and low-mid growl.

    I have a Jan Philips 5751 for sale (real cheap) or trade for one of the above types. The sound just didn't do it for me the way the Jan Philips 12AX7 does. It may not be the least noisy of tubes (the ones for lowest noise I found were the EH, and JJ/Tesla).

    I also have the original GT 12AX7 that came with the SM500 and a new JJ/Tesla for sale (also very all 3 and I'll make it a real good deal and maybe they will have the sound you are looking for :) )

    As always the tone is what i hear. I've been trying lots of tubes lately in my SM500.