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    triode switch on st-120/bias pot location



    Posts : 37
    Join date : 2011-09-04

    triode switch on st-120/bias pot location

    Post by pscottlowe on Tue Feb 07, 2012 8:51 am

    I have an st-120 on its way(built july 2011 with all the options) when this amp has the triode switch in the old bias pot location how do you set the bias in other words where are they located and what is the setting? my original st-70's are .156 but you know that.are there four (one for each) or two ( one for each pair)I thank you for the help, Scott

    Bob Latino

    Posts : 2383
    Join date : 2008-11-26
    Location : Massachusetts

    Re: triode switch on st-120/bias pot location

    Post by Bob Latino on Tue Feb 07, 2012 9:13 am


    Switch the switches to the pentode/ultralinear mode by moving the switches toward the power transformer. The bias setting is .550 volts DC for each output tube. There is a small potentiometer near each output tube that you adjust to get the correct bias setting. Email me at and I can Email you the full ST-120 wired amp owners manual. The owners manual has a more detailed explanation on setting bias on the VTA amps.


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