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    Changing VTA board to lower-gain

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    myaddiction

    Posts : 15
    Join date : 2009-03-27

    Changing VTA board to lower-gain

    Post by myaddiction on Thu Aug 05, 2010 10:10 pm

    I would like to change my hi-gain VTA board in my ST-70 to a lo-gain. I have aready replaced the center tube with a 12AU7. I would like to know which resistors I change, and to what value.

    thanks,
    Bill

    Bob Latino
    Admin

    Posts : 2413
    Join date : 2008-11-26
    Location : Massachusetts

    Re: Changing VTA board to lower-gain

    Post by Bob Latino on Fri Aug 06, 2010 6:00 am

    Hi Bill,

    Below are the resistor sets for the standard gain and the lower gain driver boards. The numbers on the right side are Mouser Electronics part numbers. Some of the numbers could be out of date and changed.

    An asterisk notes which resistors are different between the two board configurations
    Unless noted all resistors are 1/2 watt
    R40 - R43 are not on the board but are the 4 bias resistors
    R44 is a 2.2K resistor that is not on the board but goes between sections 3 and 4 of your quad cap

    Bob







    myaddiction

    Posts : 15
    Join date : 2009-03-27

    Re: Changing VTA board to lower-gain

    Post by myaddiction on Fri Aug 06, 2010 7:12 am

    Bob thanks. You mention the (4) bias resistors, and the resistor on the quad cap, but there is not an asterisk by them. So I replace them also?

    Bob Latino
    Admin

    Posts : 2413
    Join date : 2008-11-26
    Location : Massachusetts

    Re: Changing VTA board to lower-gain

    Post by Bob Latino on Fri Aug 06, 2010 7:37 am

    myaddiction wrote:Bob thanks. You mention the (4) bias resistors, and the resistor on the quad cap, but there is not an asterisk by them. So I replace them also?

    No - You already have them there since you have the VTA driver board already installed.

    Bob

    myaddiction

    Posts : 15
    Join date : 2009-03-27

    Re: Changing VTA board to lower-gain

    Post by myaddiction on Fri Aug 06, 2010 8:03 am

    That's what I thought. Thanks!

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