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Select power transformer for guitar rack preamp

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  • Select power transformer for guitar rack preamp

    Hello!

    How do i select a power transformer for a rack preamp project?

    Im thinking about using 6 to 8 preamp 12ax7 preamp tubes, it also has about 3 or 4 relays.

    what is the normal voltage used by relays?

    I think that 12ax7 heaters work it 6.3 VAC, right?

  • #2
    This might help.

    http://www.audiomatica.com/tubes/12ax7.htm

    Typically, 12AX* tubes are wired parallel filaments and operate at 6.3V and 300mA per tube. That doesn't mean you can't run series filaments if you like. There are all sorts of relays out there with different voltage and current specs. Best thing to do is look up the datasheet for the relay you intend to use.
    "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

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    • #3
      When you say 6 to 8 12AX7 tubes, do you mean 12 to 16 triodes, or just 6 to 8 triodes ?
      WARNING! Musical Instrument amplifiers contain lethal voltages and can retain them even when unplugged. Refer service to qualified personnel.
      REMEMBER: Everybody knows that smokin' ain't allowed in school !

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