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Piezoelectric Speakers

M

MRW

Jan 1, 1970
0
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
speaker?

Thanks!
 
R

Rich Grise

Jan 1, 1970
0
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 speaker?

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!
Rich
 
M

MRW

Jan 1, 1970
0
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.
 
B

Bob Masta

Jan 1, 1970
0
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
speaker?

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
though.

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
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
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