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Old 17th February 2009, 01:58 AM   #41
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Hi Maduras,

Thanks for the response.

After a brief un-tamed listening, the low frequency limit of these drivers is surprising. They're mated to a wave guide designed for car audio use. Probably 2" tall by 18" wide with 6" throat length & ~90 deg horizontal dispersion.

The characteristic sound is a bit "splashy", and similar to smaller Motorola piezos I've dealt with in the past. It's easy to feel the vibration of the inexpensive plastic waveguide. Obviously, there's room for improvement.

They are very, very efficient. And very intriguing.

Oddly, as much as I detested these drivers 20 years ago, now I feel compelled to give them a chance.
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Old 17th February 2009, 03:35 AM   #42
maduras is offline maduras  Canada
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Default piezo

Hi Tim

The EV horn is cast alluminum and wont vibrate like the one you got.My problem was with the plastic housing of the piezo it self.

Cheers

Maduras
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Old 17th February 2009, 10:24 AM   #43
pos is online now pos  Europe
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Interesting discussion!

Has anyone tried to use these small piezos (such as the small KSN1016) as supertweeters above 8 or 10khz, actively crossed over ?

How do you think they would compare to JBL 2405 or the like?

Here you can find some frequency responses and even some polar plots.
The KSN1056 looks impressive in this regard!

http://www.piezosource.com/general/P...ducts_list.htm
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Old 17th February 2009, 05:59 PM   #44
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Default Nice web page on piezos

I found this web page about the Motorola/CTS line of piezos which actually explains how they work. They use the term "momentum drive principle" to describe it. This link pretty well covers everything we have discussed here in this thread, including crossovers, parallel/series arrangements, notch filters, and the theory of operation.

http://www.pulsardevelopments.com/pr...l/piezoan.html


These experiments have got me thinking that it should be possible to make a simple and pretty compact Phy style tweeter out of one of these cheap piezos if you have a lathe and can fabricate a housing that will enclose the disk at one end and provide a rim to hold the edge of the diaphragm at the other end. I will start working on a "MyPhy" tweeter soon. Prototype to made in PVC since it is inexpensive and reasonably damp.
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Old 17th February 2009, 06:27 PM   #45
HK26147 is offline HK26147  United States
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Quote:
Has anyone tried to use these small piezos (such as the small KSN1016) as supertweeters above 8 or 10khz, actively crossed over ?
Perhaps no group has tinkered more with piezos than the Bill Fitzmaurice forum. His designs use large numbers of them.
Numerous individuals has run piezos actively BUT always with a resistor to stabilize the load to the amp.
On more than one occasion an amp has gone into ultrasonic oscillation and failed, because of the capacitive nature of piezos, when a resistor was NOT included.
Piezos are capable of reproducing signals well above human hearing.
Indeed they are used for that purpose as ultrasonic bug, bat and vermin repellent.
They should be limited to 25 - 27V.
Users of piezos in Pro Sound report their limitations vs compression horns.
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Old 5th August 2013, 11:58 AM   #46
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I'd like to have a Piezo roll in (12db / oct) at approx 10khz... how might I do this ?
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Old 5th August 2013, 12:30 PM   #47
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Originally Posted by clubsport911 View Post
I'd like to have a Piezo roll in (12db / oct) at approx 10khz... how might I do this ?
In general, you put a resistor in parallel with the Piezo Tweeter, and design the crossover to that resistance.

Though 10khz is pretty high. As the frequency goes up the impedance goes down on a Piezo. In the past, I've seen impedance charts for Pieso tweeters, so I know they exist, but that was a long time ago and I don't remember the details.

As some point the impedance of the Piezo is going to get low enough that the impedance is going to be a blend of the Piezo and the resistor.

Can you explain why you would need to cross as high as 10khz?

I spoke about how I did this in an earlier post, and I think someone posted a link confirming my use of a resistor to control the impedance of the Piezo and allowing it to be used with a standard crossover network.

Steve/bluewizard
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Old 5th August 2013, 03:31 PM   #48
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Thanks for the reply. Long story short, I'm looking to add a "supertweeter" concept to one of my audio systems and thought to use a Piezo unit (they have v good HF performance). I have tweeters now but I dare bet they fall off at moderate freqencies. In effect, its supplementary treble only.

Rgds
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Old 5th August 2013, 08:05 PM   #49
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Frugal-phile | Piezo Tweeter Crossovers | J Risch

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