The Dynaco Tube Audio Forum

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The Dynaco Tube Audio Forum

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


2 posters

    AC Balance

    VikeMan
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    VikeMan


    Posts : 3
    Join date : 2010-11-21
    • Post n°1

    AC Balance Empty AC Balance

    Post by VikeMan Sun Nov 28, 2010 10:43 am

    So the VTA70 board has an AC balance feature, which I understand should not be adjusted without the right measuring equpment. But what exactly does this feature do, and if different driver/splitter tubes are rolled in, would it need to be adjusted? TIA!

    ---VikeMan
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    Bob Latino
    Bob Latino
    Bob Latino
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    Posts : 3262
    Join date : 2008-11-26
    Location : Massachusetts
    • Post n°2

    AC Balance Empty Re: AC Balance

    Post by Bob Latino Sun Nov 28, 2010 11:58 am

    VikeMan wrote:So the VTA70 board has an AC balance feature, which I understand should not be adjusted without the right measuring equpment. But what exactly does this feature do, and if different driver/splitter tubes are rolled in, would it need to be adjusted? TIA!

    ---VikeMan

    Hi VikeMan,

    The AC balance control adjusts phase splitter section of the VTA driver board. If you set the AC balance as outlined in the VTA board manual you will be fine. By setting the AC balance control in the CENTER as outlined in the manual, you presume that the two output tubes you are using are a matched pair and exactly half the audio signal is sent to each output tube of the pair. The signal in each output tube is 180 degrees out of phase with the other tube of the pair. Do not worry that "you don't have it right" or it might be "off a little". I have misadjusted it slightly on purpose and could hear no change in the sound of the amp. There is no need to really "fine tune" this control even if a different phase splitter/phase inverter tube is rolled in.


    Bob
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