Hi.
Being each resonant to a single frequency; could piezoelectric transducer thin discs work at a wider response by paralleling many different sizes, a tiny, an almost tiny, a small, a medium, a large and a largest ? Would their Bode plot just superimpose?

 

That is an interesting concept.

 

Motorola managed to get a single element to work over about 3 octaves, but it wasn’t exactly a flat response. Given the shape, one would expect a series of resonant frequencies governed by a first order Bessel function.
This is the original paper, but it’s behind a paywall at AES.

• Title: A New Type of Tweeter Horn Employs a Piezo-Electric Driver
• Author / Affiliation: Jonathan R. Bost, Motorola, Inc. (Franklin Park, IL)
• Publication: Presented at the 49th AES Convention, September 1974 (Paper Number 977).

 

Many years ago I had a MOTOROLA (I think it was) Record player that had electrostatic TWEETER speakers and electrodynamic midrange and bass speakers. Strictly monophonic, since stereo was not yet "The Big Thing"! The frequency response was quite good at moderate sound levels, but the highend fell off at higher volume levels.

 

Electrostatic is not piezoelectric.

 

My concern about a piezo speaker that looked like those brass discs is the very sharp resonence.
I have seen a piezo tweeter but i would not choose to purchase one.

 

My concern about a piezo speaker that looked like those brass discs is the very sharp resonence.
I have seen a piezo tweeter but i would not choose to purchase one.

Certainly not for hifi. They make good alarm sounders. A real one is just a collection of those very sharp resonances!

 

Of course, it is entirely possible to attach a piezo driver to a NON-RESONANT diaphram, which must be how the tweeter speakers must work. I am not familiar with the details of piezo tweeters. I understand the principle, but not the details.

 

Of course, it is entirely possible to attach a piezo driver to a NON-RESONANT diaphram, which must be how the tweeter speakers must work. I am not familiar with the details of piezo tweeters. I understand the principle, but not the details.

The don't look much different. I think there might have been a very light sponge attached to damp the worst of the resonances, but it's a while since I last took one apart.