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Piezo high quality mikes

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  • Richard Lee
    ... I m only a beach bum pretending to be an ex-speaker & microphone guru. I ve never made a piezo mike; only some noisemakers & ultrasonic sources. I have no
    Message 1 of 5 , Aug 2, 2006
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      >(Listen to Richard Lee's comments on the types of piezo transducers, though, He either really knows his stuff or if not, he has me quite buffaloed! ;)

      I'm only a beach bum pretending to be an ex-speaker & microphone guru.

      I've never made a piezo mike; only some noisemakers & ultrasonic sources.

      I have no experience at all on stuff you stick to guitars etc.

      >But if used, like electret film, PVDF film should produce very good mikes. Anyone heard of developments on this front? I remember at least 1 AES paper by Mitsubishi (I think)

      >Manfred, have you seen those balloons which play music? Made from PVDF film. The film is rather thick but if you can get some, its worth trying as a diaphragm for your mike. No need for polarizing voltage and LOADSA output.

      These comments are only from a theoretical study. I've never made one of these but the operating principle is so obvious that I'm surprised no one has done anything in the last 15 yrs. What I don't know is how stable it is over time etc. Yarsley (?) the original PVDF film manufacturers, were hoping to target the (new at that time) mobile phone market.

      PVDF film gives a voltage if you poke it. If you use it as the diaphragm of a condensor mike, when the diaphragm moves, you get volts out. But MUCH more than with an electret. The motion is controlled by all the other stuff that is important in a condensor mike which Manfred was kind enought to detail recently, is in the B&K paper that Eric put in our Files section, but best of all in a pdf book from the Neumann website.


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    • Mike Darling
      FWIW, I ve only heard of PVDF being useful in ultrsound transducers & hydrophones. The guy that taught my electroacoustics class worked for B&K doing
      Message 2 of 5 , Aug 2, 2006
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        FWIW, I've only heard of PVDF being useful in ultrsound transducers &
        hydrophones. The guy that taught my electroacoustics class worked for
        B&K doing hydrophone work, so if there had been an application in
        microphones as we like to use them, I bet he'd have said something.

        -mike

        --- In micbuilders@yahoogroups.com, Richard Lee <ricardo@...> wrote:

        > These comments are only from a theoretical study. I've never made
        one of these but the operating principle is so obvious that I'm
        surprised no one has done anything in the last 15 yrs. What I don't
        know is how stable it is over time etc. Yarsley (?) the original PVDF
        film manufacturers, were hoping to target the (new at that time)
        mobile phone market.
      • Richard Lee
        ... hydrophones. The guy that taught my electroacoustics class worked for B&K doing hydrophone work, so if there had been an application in microphones as we
        Message 3 of 5 , Aug 2, 2006
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          >FWIW, I've only heard of PVDF being useful in ultrsound transducers &
          hydrophones. The guy that taught my electroacoustics class worked for
          B&K doing hydrophone work, so if there had been an application in
          microphones as we like to use them, I bet he'd have said something.

          I'm not sure you've got this right. Piezo transducers are good for ultrasound which includes hydrophones.

          But PVDF transducers are VERY low acoustic impedance. Almost useless for these applications.

          Unless the piezo coeffs for PVDF have increased by an order of magnitude in the last 15 yrs. they would only be interesting for toys. eg the balloons.



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        • Michael Darling
          You re probably right - now that I think about it I believe we were using the PVDF sensors at work (shock and vibration measurement) and piezo was the big
          Message 4 of 5 , Aug 2, 2006
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            You're probably right - now that I think about it I believe we were
            using the PVDF sensors at work (shock and vibration measurement) and
            piezo was the big thing in the class. It got rebranded as a
            "biomedical imaging" class right after I registered for it...

            -mike

            On Aug 2, 2006, at 4:34 PM, Richard Lee wrote:

            > I'm not sure you've got this right. Piezo transducers are good for
            > ultrasound which includes hydrophones.
            >
            > But PVDF transducers are VERY low acoustic impedance. Almost
            > useless for these applications.
            >
            > Unless the piezo coeffs for PVDF have increased by an order of
            > magnitude in the last 15 yrs. they would only be interesting for
            > toys. eg the balloons.
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