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Noisy PGA-04 loadbox...

Discussion in 'Electronic Basics' started by Mack North, Feb 6, 2004.

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  1. Mack North

    Mack North Guest

    I have a strange little problem with a used Palmer PGA-04 I got
    recently. (It's a speaker emulator w/ a built-in 8-ohm load; handles
    up to 120 watts rms. Transforms speaker-level output from an amp to
    line-level.) I'm running a 100-watt guitar amp in, and everything
    seems to work OK -- I get a nice, clean tone from the line-out.
    However, the unit itself seems to be trying to act like a speaker! It
    makes a very annoying noise that very obviously corresponds to the
    signal coming in (i.e., I strike a chord on my guitar and it starts
    buzzing). I opened it up and the sound appears to be coming from
    around the area where there are 3 little 12V 75W halogen bulbs that
    help dissipate power. There's some other circuitry and a little
    transformer nearby also, so I can't really say for sure that it's the
    bulbs. In any case, it is fairly loud. I can hear it from across the

    Which brings me to my question(s): can halogen lamps produce sound if
    you run an audio signal through them? Is this normal? If not, are
    there any other typical electronic components that can actually
    produce sound this loud (if not working properly or something)? If
    anybody else actually does have a PGA-04, does the same thing happen
    on yours?

    Any help appreciated, thanks!
  2. Lord Valve

    Lord Valve Guest

    Go to Google Groups and search for "magnetostriction" using
    as the author.

    Lord Valve
  3. Mack North

    Mack North Guest

    Ah that explains it. Thanks man.
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