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Piezoelectric Speakers

Discussion in 'Electronic Basics' started by MRW, Feb 8, 2006.

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  1. MRW

    MRW Guest

    Hi all,

    Has anyone ever dealt with piezoelectric speakers? I was reading an
    article and it mentioned using Class D amplifiers to drive the
    speakers. I thought that piezo speakers relied more on overall voltage
    swing to produce instead of the actual current draw to drive the
    speaker. How does a Class D amplifier provide more "oomphf" to a piezo

  2. Rich Grise

    Rich Grise Guest

    It doesn't. It just wastes less "oomphf" inside itself than a class A or
    AB or B amp does. At the speaker, they've got the same oomphf.

    The class of the amp isn't related to the speaker technology, except to
    the extent that the speaker has to make sound when presented with the
    electron faeries from the output amp. ;-)

    Hope This Helps!
  3. MRW

    MRW Guest

    Thanks, Rich! :)

    After reading National's text on piezo speaker technology, I was just a
    bit curious why a class D would be used to provide the voltage swing
    that the speaker needs. From my basic understanding of class D, there
    is a comparator hook up to two MOSFET connected together. The class D
    text also stated that the voltage drop at the output when one of the
    MOSFET is on should be zero or close to the bias voltage. I was
    actually expecting more of a bridge tied load amplifier to provide the
    high voltage peak to peak to produce a louder sound.
  4. Bob Masta

    Bob Masta Guest

    I recall many years ago when "digital audio" was the
    latest craze, that some people were talking about
    making honest-to-god digital speakers (not "digital-ready").
    One idea was to have have the speaker integrate the
    pulse-width-modulated amp output, with the inertia of the
    speaker providing the integration... perfect for class D.
    I don't see how piezos would have any advantage here

    The wilder idea was to have arrays of little on-off transducers
    that could be driven with binary weighting to produce
    the desired overall displacement. Piezo might be a
    good match for this, but not class D... in fact, the amp
    would just be one power switch for each digital bit.
    I guess you would have needed 16-channel speaker cables.
    (Now THERE'S a concept that the Monster Cable people
    would love!)

    Best regards,

    Bob Masta

    D A Q A R T A
    Data AcQuisition And Real-Time Analysis
    Home of DaqGen, the FREEWARE signal generator
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