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Field Coil Speaker

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  • Field Coil Speaker

    One question: Is it dangerous to touch a field coil speaker? PM speakers should not be dangerous, but I always wondered if my old M2 field coil speaker has a deadly voltage. I made a back panel for the upper (TWG) part of my m2. But if touching the speaker could kill someone, I should do the same for the lower part.

    greetings Christian
    1958 B3, 1960 M3, 1953 M2 converted into M3, 2x Leslie 122, Ventilator II, Viscount Legend Solo

  • #2
    The short answer is no. The long answer is - maybe - if the insulation to the wires is degraded, or if the wires have been cut / spliced poorly.

    The large field coil is one part, and has two wires going into and out of it. Those two wires vary in color (usually gray and brown, or something dark) and should not have any exposed terminals.
    -- On the back end of the field coil is a pancake-like "hum bucking" coil. That one does have exposed terminals. It connects to one or more of the voice / ground terminals of the amp. It does not receive high voltage so touching it is not necessarily dangerous.

    If the wiring is in good condition with no cuts or exposed insulation, there is no need to be worried of a shock hazard from touching the field coil or its wiring. Making a back cover that hides the entire back of the organ is a good idea though, as long as there is some ventilation for the tubes.


    • #3
      The maximum voltage across a field-coil in an M-series spinet is around 100 Volts DC. The wires to it are all insulated, and there is an insulating sleeve around the field coil. I would say that it's generally pretty safe, but I'm sure one of our other members will come along and tell you that it's highly dangerous since there are different cultural mindsets about such things, particularly in Europe.

      I've worked around these things for years while they're powered up and have never had a problem.
      I'm David. 'Dave' is someone else's name.