The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Dynaco VTA tube amp kits, all Tubes4hifi.com products and all Dynakitparts.com products


    12AU7 vs 12AT7 in VTA boards

    Share

    Guest
    Guest

    12AU7 vs 12AT7 in VTA boards

    Post by Guest on Sun Oct 16, 2011 11:46 pm

    Has any one tried the VTA boards set with the 12AU7, as well as the 12AT7 in their amp/amps? Which did you prefer, Thanks[b]

    baddog1946

    Posts : 304
    Join date : 2010-02-03
    Location : Costa Rica

    Re: 12AU7 vs 12AT7 in VTA boards

    Post by baddog1946 on Mon Oct 17, 2011 9:29 am

    Depends on what you are driving with the amp and what speakers you have.

    Bob Latino
    Admin

    Posts : 2378
    Join date : 2008-11-26
    Location : Massachusetts

    Re: 12AU7 vs 12AT7 in VTA boards

    Post by Bob Latino on Mon Oct 17, 2011 11:07 am

    There is no real difference in the "quality of sound" between the VTA standard gain 12AT7 board and the VTA lower gain 12AU7/12BH7 board. The circuit is the same. It is just that 8 resistors on each channel are different and the driver tubes are different. The key thing here is the efficiency of your speakers. With normal efficiency speakers (anything up to about 93 dB efficiency) the standard gain 12AT7 board is probably your best bet. Anything over 93 dB efficient speakers, you are probably better off with the lower gain 12AU7/12BH7 board.

    Bob

    Guest
    Guest

    Re: 12AU7 vs 12AT7 in VTA boards

    Post by Guest on Mon Oct 17, 2011 11:20 am

    Bob: I am using Rogers LS3/5A's, the 8 ohm version, and/or Quad ESL 57's. I know the Quads can be difficult to drive. People with a much better knowledge of these things than I, have suggested that the 12AT7 is a more linear tube.

    Bob Latino
    Admin

    Posts : 2378
    Join date : 2008-11-26
    Location : Massachusetts

    Re: 12AU7 vs 12AT7 in VTA boards

    Post by Bob Latino on Mon Oct 17, 2011 11:37 am

    Michael,

    The 12AT7 of the standard gain VTA driver board IS a very linear tube at virtually all drive levels and is the preferred tube to use as long as you don't have 100 dB efficient Klipsch speakers or some other high efficiency speakers. As a side note, Louis Chochos, the owner of Omega Speakers in Connecticut, uses a standard gain 12AT7 driver circuit on his VTA ST-70 (at times) to demonstrate his speakers. His speakers run from 93 to about 96 dB efficiency. I am sure he also uses other amps besides his VTA ST-70 for demonstration purposes.

    Bob

    Sponsored content

    Re: 12AU7 vs 12AT7 in VTA boards

    Post by Sponsored content Today at 6:18 pm


      Current date/time is Sat Oct 01, 2016 6:18 pm