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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


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    Power transformer primary line voltage rating for M 125 amps.

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    Frank111


    Posts : 105
    Join date : 2015-02-23
    Location : Minneapolis/StPaul Area

    Power transformer primary line voltage rating for M 125 amps. Empty Power transformer primary line voltage rating for M 125 amps.

    Post by Frank111 Wed Dec 12, 2018 1:59 pm

    What is the actual line voltage rating for the power transformers in the M-125 amps? What voltage have they been designed for?
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    BNR_1


    Posts : 111
    Join date : 2013-06-11

    Power transformer primary line voltage rating for M 125 amps. Empty Re: Power transformer primary line voltage rating for M 125 amps.

    Post by BNR_1 Wed Dec 12, 2018 4:43 pm

    I don’t know what the tranny was designed for incoming voltage but I recall the optimum range is 117 to 121V AC with 118 as the sweet spot.
    Bob Latino
    Bob Latino
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    Power transformer primary line voltage rating for M 125 amps. Empty Re: Power transformer primary line voltage rating for M 125 amps.

    Post by Bob Latino Wed Dec 12, 2018 8:12 pm

    Frank111 wrote:What is the actual line voltage rating for the power transformers in the M-125 amps? What voltage have they been designed for?

    The power transformers on all the VTA amps are rated for a nominal voltage of 120 VAC but will work fine from about 115 VAC up to 122 VAC. If your line voltage is over 122 VAC, you should run the amps off a variac. If you do run your amp off a variac, I recommend set the output on the variac to about 118 VAC.

    Bob

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    Frank111


    Posts : 105
    Join date : 2015-02-23
    Location : Minneapolis/StPaul Area

    Power transformer primary line voltage rating for M 125 amps. Empty Re: Power transformer primary line voltage rating for M 125 amps.

    Post by Frank111 Thu Dec 13, 2018 11:17 am

    Bob,

    Thanks for clearing this up for me. I've been running my M-125 amps using the copper solid state rectifier and 4 Tung-Sol KT-120 tubes per amp and have not have any issues.
    My line voltages runs pretty much around the 120 volt point. So I should be ok as I am now without resorting to any voltage reduction devices.

    Also, I'm going to keep the simplicity of not installing the automatic bias board. I don't mind checking the bias now and then, and I'm not a tube roller either.

    So far, been very happy with the M-125 amps, and have recommended them many times. Still the best quality and value out there.

    Frank.

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