12DW7 Preamp Tube - Where Would You Use It?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Electric I, Aug 7, 2006.


  1. Electric I

    Electric I Member

    Messages:
    3,015
    Joined:
    Sep 17, 2005
    Came across this oddball tube just recently & gotta wonder:

    With it's 'contradictory' triode gain ratings (one half is 100, while the other is 20), where would you use it?

    Which half of the tube gets hit with signal first?

    Could the tube be likened to a stacking of od/dist pedals - as in one having the gain fully cranked & the other with the gain turned down?
     
  2. PaulM

    PaulM Member

    Messages:
    177
    Joined:
    Nov 28, 2005
    Location:
    Wild Wild West
    Andy at THD says its his favorite driver tube in the univalve. You can check his posts on it on the old univalve board.
     
  3. trdlasvegas

    trdlasvegas Member

    Messages:
    167
    Joined:
    Aug 30, 2005
    Location:
    Las Vegas
    If I'm not mistaken, I think it was used in early Ampeg SVT's.

    -Tony
     
  4. Jon Silberman

    Jon Silberman 10Q Jerry & Dickey Gold Supporting Member

    Messages:
    35,863
    Joined:
    Jan 3, 2002
    Location:
    Northern VA
    I'm using one in my Tone King Continental. The tube is split, on side serves as gain stage 3 for the lead channel, the other is the trem driver. I run the 20X side to the lead gain stage (for a more authentic tweed tone as opposed to "tweed on steroids"), the 100X side to the trem.
     
  5. Jeff West

    Jeff West Member

    Messages:
    803
    Joined:
    Mar 26, 2003
    Location:
    Houston, TX
    Cool for plug-in in V1 of two channel AC50; you get the stock 12AU7 gain structure on the Normal/Bass Channel, and higher gain AX7 blasting on the Lead.

    Pins 1,2,3 are the lower gain, AU7 triode; 6,7,8 are AX7 half.
     
  6. Electric I

    Electric I Member

    Messages:
    3,015
    Joined:
    Sep 17, 2005
    Great info, everyone. Thanks a lot.

    How do you think it'd react in a V1 position where it solely feeds the tone stack?
     
  7. mc5nrg

    mc5nrg Supporting Member

    Messages:
    8,045
    Joined:
    Mar 15, 2004
    Location:
    DC, Philly, Asquared, Upper Michigan
    Stock in some amps like certain Magnatone models.
     
  8. donnyjaguar

    donnyjaguar Member

    Messages:
    4,232
    Joined:
    Nov 4, 2005
    Location:
    Canada
    I think that tube was designed for use as a Voltage Amplifier and a Williamson Phase Splitter in one bottle. I'll guess that's what the W is for in the name.
     
  9. dewman

    dewman Gold Supporting Member

    Messages:
    5,749
    Joined:
    Nov 23, 2005
    Location:
    NC
    ampeg V series amps, one half is a 12AU7 and the other half a 12AX7.
     

Share This Page