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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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    Does heater phase matter?

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    bobgroger


    Posts : 18
    Join date : 2021-02-12

    Does heater phase matter? Empty Does heater phase matter?

    Post by bobgroger Sat Feb 20, 2021 2:38 pm

    Working on the ST-120 today. I started wondering since there are 2 6.3v heater windings does the phase matter between the windings, and even between the tubes? I am thinking that since the tubes are indirectly heated probably not, but it seems the hum could be additive or cancelling depending on how it is wired. Am I overthinking this?
    Bob Latino
    Bob Latino
    Admin


    Posts : 3279
    Join date : 2008-11-26
    Location : Massachusetts

    Does heater phase matter? Empty Re: Does heater phase matter?

    Post by Bob Latino Sat Feb 20, 2021 3:41 pm

    bobgroger wrote:Working on the ST-120 today. I started wondering since there are 2 6.3v heater windings does the phase matter between the windings, and even between the tubes? I am thinking that since the tubes are indirectly heated probably not, but it seems the hum could be additive or cancelling depending on how it is wired. Am I overthinking this?

    Bob,

    On the octal output tube sockets pins 2 and 7 are the filament or heater pins. When the manual tells you to connect the two twisted wires to pins 2 and 7, it does not matter which wire is connected to pin 2 and which wire is connected to pin 7.

    Note 1 - if there was a difference, then the assembly manual would mention the difference.

    Note 2 - If the manual does not mention about twisting wires, then it is unnecessary to twist the wires.

    Bob

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