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    Dual control bias modification for ST-70


    Posts : 4
    Join date : 2015-01-10
    Location : Sendai, Japan

    Dual control bias modification for ST-70

    Post by lorne on Mon Jan 12, 2015 3:54 am

    Greetings Brother & Sister Dyna Fans: after being a guest for some time, this is my first post — an inquiry.

    I bought my 1960's vintage ST-70 from a friend back in '89. I moved to Asia in 1993, so it was stored for years. When it finally caught up with me in Japan, I decided to rebuild it. I got half way and — life happened. So it parked for some years. Now I am hot to get it running once again. It will be teamed up with a Melos 1+1 tube preamp. (They make for a perfect marriage!)

    I have kept my '70' as close to stock configuration as possible but for these essential changes: (a) the upgraded PA-060-S power transformer, and most importantly here (b) a Triode Electronics (USA) capacitor board.

    QUESTION:Has anyone installed the Dynakit's Dual Control Bias kit with the Triode cap board?

    This kit allows for each output EL-34 or whatever to be biased individually — one tube on either side is initially biased, and the remaining two balanced in turn.

    Best regards to all — Lorne

    Posts : 30
    Join date : 2010-10-05
    Location : North Shore,Ma.

    Re: Dual control bias modification for ST-70

    Post by dmag on Sat Jan 31, 2015 4:08 pm

    I'm running them on two ST70's. Both have stock driver boards,one from Dynakitparts. They work as advertised.
    Be sure to read his description carefully. The bias procedure is a bit different than your description.

      Current date/time is Wed Jun 20, 2018 3:32 am