Tube for Preamp

Discussion in 'Amps and Cabs [BG]' started by David Vega, Dec 18, 2005.

  1. David Vega

    David Vega

    Aug 28, 2002
    Puerto Rico
    Hi all!
    What brand a model of a good tube for the SVP-BSP. I want high gain, warm tube sound. This preamo wll hold only one tube. The one installed is a Electro Harmonix, 12ax7

    Any thoughts
  2. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    SW, OK
    The EH that's already in it is pretty good for Rock (there may be some variation in the quality of the tube itself, though).

    Telefunken ECC83 are usually higher than average gain and (from all reports) very good tone.

    I like the balanced sound of Jan Philips 12AX7WA.
  3. fremenblue


    Jan 8, 2003
    Eugene, Or.
    Any other tube choices/preferences? I'm in the same boat with the same preamp.
  4. A9X

    A9X Inactive

    Dec 27, 2003
    Tube sonic signatures are massively overrrated, so don't waste your money or time.

    Any tube, eg a 12AX7 that provides more gain, is no longer a 12AX7. Mu should be close to 100, and it's damnably hard to get a tighter grid spacing to make it higher, so I don't believe the new TFK gain claims until I see it on the bench.
  5. Crabby


    Dec 22, 2004
    I have a new EHX 12AX7 in my SWR Bass 350 and it is a nice sounding tue. There was a brand X tube in the amp when I got it and it hummed a bit, The new tube took care of the hum and the tone seemed more open and somehow cleaner with the new tube.
  6. fremenblue


    Jan 8, 2003
    Eugene, Or.
    I've got two tubes on order. One is a Tung Sol 12ax7. The other is a Sovtek 5751 SRV Tube, I believe it is the same as a 12au7, suppose to help tame an overly "gainy" amp. If it doesn't work well in my BSP preamp I'll try it in my Mesa/Boogie 400+.
  7. Tim1


    Sep 9, 2005
    New Zealand
    Hi Fremenblue - put the 12AU7 in the driver position of your 400+ and you will never look back. It is a revelation.
  8. fremenblue


    Jan 8, 2003
    Eugene, Or.
    Looking at the back of the amp, which would be the driver position? I'd love to retube the whole dang thing and have a bias pot put in. I've just never been happy with the amp, not for what it cost me. It may yet find itself replaced with an SWR Super Redhead.
  9. amos


    Oct 23, 2003
    SE Portland Oregon
  10. A9X

    A9X Inactive

    Dec 27, 2003
    A 12AU7 is not the same as a 5751. A 5751 may be substituted for a 12AX7 for decreased gain with no modification to the circuit. Mu (intrinsic gain of tube) is 100 for a 12AX7 and 70 for a 5751. Actual gain in circuit will be lower.
  11. fremenblue


    Jan 8, 2003
    Eugene, Or.
    Thanks for straightening me out! :bassist:
  12. A9X

    A9X Inactive

    Dec 27, 2003
    A pleasure sir.
  13. mrpackerguy

    mrpackerguy Supporting Member

    Jul 3, 2004
    Madison, Wisconsin
    The EH's have not let me down with my Kern.
  14. svp


    Mar 12, 2007
    A Ruby will warm it up, but I don't know as far as increased gain. Last time I checked there were only like 3 companies in the world that made the tubes that all the other companies stick their decals on.
  15. mark roberts

    mark roberts Supporting Member

    Nov 13, 2004
    Lawrence, KS
    GT ECC83/7025
  16. musicelectronix


    Jul 8, 2007
    Hüstın, TX
    Lead Designer, Zeibek Boutique Pedals
    my 2 cents, EH is an OK tube, average quality with very good price, 3 of the 10 I got had noise issues. They are made by Sovtek, Russia. Jan Phillips and regular made in Holland Phillips are really good, but they are a bit pricy and you need to find NOS tubes for both. Older Tesla tubes are the best, but they go around $80.

    I just ordered a couple of new Teslas - also known as JJ - and Mullard reissues, I can report back in 2-3 days I guess. Their price is around $8-10 for JJ and $15-20 for Mullard Reissue.

    For the technical perspective, I say go with 12ax7/ecc83. 12ua7 will have more headroom, hence lesser gain.
  17. A9X

    A9X Inactive

    Dec 27, 2003
    The 12AU7 will have less gain because it has less gain: mu=20. It will usually not bias up correctly/well in a cct designed for a 12AX7.
  18. musicelectronix


    Jul 8, 2007
    Hüstın, TX
    Lead Designer, Zeibek Boutique Pedals
    be that as it may :)
  19. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    +1...almost. Replaced the stock EH 12AX7 with a NOS Brimar (made in England). It warmed the Demeter up a bit but, in the larger scheme of things, the overall change was not profound. Not a complete waste of time / $$$ as I've learned from the experience.

  20. fremenblue


    Jan 8, 2003
    Eugene, Or.
    I've put a Tung Sol 12ax7 in my SVP-BSP just today and am very pleased with the results. The clean side is sweet as Texas Tea and the drive side is much more manageable now. I plan to use the same tubes in my 400+.