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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

    Another wall voltage question.

    Dave_in_Va
    Dave_in_Va
    Dave_in_Va


    Posts : 446
    Join date : 2013-04-02
    Location : Mid. VA
    • Post n°1

    Another wall voltage question. Empty Another wall voltage question.

    Post by Dave_in_Va Wed Aug 12, 2015 2:38 pm

    I have a VTA ST70 (thanks Sal) and a VTA SP/PH 10 (thanks Troy) that sounds great.
    I have about 122/123 volts at the outlet. I also have a bucking transformer that will knock this down to about 115v.

    Does it make any difference which voltage I chose to use?

    Thanks in advance.
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    Bob Latino
    Bob Latino
    Bob Latino
    Admin


    Posts : 3276
    Join date : 2008-11-26
    Location : Massachusetts
    • Post n°2

    Another wall voltage question. Empty Re: Another wall voltage question.

    Post by Bob Latino Wed Aug 12, 2015 2:47 pm

    Dave_in_Va wrote:I have a VTA ST70 (thanks Sal) and a VTA SP/PH 10 (thanks Troy) that sounds great.
    I have about 122/123 volts at the outlet. I also have a bucking transformer that will knock this down to about 115v.

    Does it make any difference which voltage I chose to use?

    Thanks in advance.

    Hi Dave,

    Using the amp at 122 - 123 VAC may shorten tube life a bit. It will raise the DC voltages inside the amp somewhat higher than normal. I would try the amp at 115 VAC with your bucking transformer. If it sounds OK, I would use it with the bucking transformer. Tube life will be extended and the amp will not produce as much heat. You may lose 2 or 3 watts of power but you probably won't notice the very slight loss of power.

    Another idea is to substitute a 5U4 for whatever rectifier you are now using (without using the bucking transformer). The use of a 5U4 will drop the DC voltages in the amp and extend tube life a little. This rectifier substitution also comes with a very slight loss of power. ..

    Bob
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    Dave_in_Va
    Dave_in_Va
    Dave_in_Va


    Posts : 446
    Join date : 2013-04-02
    Location : Mid. VA
    • Post n°3

    Another wall voltage question. Empty Re: Another wall voltage question.

    Post by Dave_in_Va Wed Aug 12, 2015 4:37 pm

    Hi Bob,
    Thanks for the info. I just hooked up the bucking transformer*. The bias dropped on each tube about 4-5 mV. Re-biased and everything still sounds gorgeous.
    Man, I love this gear.

    * I paid the big bucks for a NOS Mullard 5AR4 so I'm gonna use it no matter what ;-)
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    • Post n°4

    Another wall voltage question. Empty Re: Another wall voltage question.

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