Preamps: replacing 12ax7 with 12au7?

Discussion in 'Amps [BG]' started by Seedouble, Jan 27, 2014.


  1. Seedouble

    Seedouble

    Joined:
    Feb 13, 2007
    Hi there,

    I've been using an Alesis MicTube Duo at the end of my chain for recording recently and I think it warms up the sound quite a bit.

    Since it starts peaking at 9pm on the dials, I wonder what would happen if I changed it out for a 12au7?

    I went to a local music shop and the guy said he'd never heard of anyone wanting to do anything like what I was talking about. Besides, he didn't have them in stock anyway.

    Would I really just be making it so I can turn the gain knob up higher? Would there be any real benefits to this "mod" anyway?

    Cheers.
  2. BurningSkies

    BurningSkies Supporting Member

    Joined:
    Feb 20, 2005
    Location:
    Seweracuse, NY
    Do it and find out. or alternately, you could use something slightly more gain than the AU, and use a 5751.

    I like the 12AU7 and the 5751 better than the 12AX7.
  3. scf4003

    scf4003

    Joined:
    May 2, 2004
    I've used a 12AU7 in the preamp section of Marshall, Orange and HiWatt amplifiers to reduce the gain, it works very well
  4. B-string

    B-string Supporting Member

    Joined:
    Nov 21, 2008
    Location:
    Lake Havasu City, Az USA
    I did just that for one channel on a V4-B, made it more friendly to an active bass. I kind of liked the character of the sound better as a bonus.
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  6. wcriley

    wcriley

    Joined:
    Apr 5, 2010
    Location:
    Western PA
    Disclosures:
    Uncompensated endorsing user: fEARful
    I swapped a 12AT7 in place of a 12AX7 in the "dirty" channel of a guitar amp and liked the results. Higher gain than an AU, but lower than an AX.
  7. BurningSkies

    BurningSkies Supporting Member

    Joined:
    Feb 20, 2005
    Location:
    Seweracuse, NY
    B-String suggested that I put a 12AU7 in the V1 of my Fender Twin Reverb to clean up the messy low end it had, and it worked very well. Sounds great now.

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