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    filament transformer question

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    Captain Coconut

    Posts : 209
    Join date : 2009-10-13
    Age : 64
    Location : Great White North

    filament transformer question

    Post by Captain Coconut on Fri Mar 25, 2016 11:26 am

    If you were to wire a single 12AX7 with its own transformer - I know it's kinda' overkill - and it had a center tap, would you choose a 12.6VAC transformer, and wire it in series, or pick a 6.3VAC and wire it in parallel?

    I'm thinking the "best" way would be a 12.6 VAC and wire one lead to pin 4, the other wire to pin 5, ignore the pin 9 connection, and wire the center tap to star ground. Does this sound good?

    peterh

    Posts : 641
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: filament transformer question

    Post by peterh on Sat Mar 26, 2016 4:13 am

    using 12V will reduce current to half, this wil give less magnetic disturbances ( injected hum) on
    other parts. And grounding the center will have static fields cancelling, but they are seldom significant.
    Yes, it's the optimal way. The only improvement is to rectify and use DC ...

    Captain Coconut

    Posts : 209
    Join date : 2009-10-13
    Age : 64
    Location : Great White North

    Re: filament transformer question

    Post by Captain Coconut on Sat Mar 26, 2016 10:36 am

    Thanks peterh. It stands to reason that wiring a second 12AX7 in series from the same transformer would require 25.2VAC.

    peterh

    Posts : 641
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: filament transformer question

    Post by peterh on Sat Mar 26, 2016 3:36 pm

    Captain Coconut wrote:Thanks peterh. It stands to reason that wiring a second 12AX7 in series from the same transformer would require 25.2VAC.
    You have a choice to wire two 12ax7 for 12V or 24V.

    j beede

    Posts : 316
    Join date : 2011-02-07
    Location : California

    Re: filament transformer question

    Post by j beede on Sat Mar 26, 2016 4:03 pm

    Dr. Kirchhoff to the DTF... stat

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