question about piezos...

[tnptruck]

Hi I was wondering if someone could help me figure out which resistor to put on this piezo tweeter that I am running with an 8 in dayton classic woofer.

This is the woofer: Dayton Audio DC200-8 8" Classic Woofer 295-310


The piezo: Goldwood GT-400CD Bullet Piezo Horn Driver 270-069

I put a 4.7 on the piezo and it soundfine but im not sure if im getting the midrange frequencies. What would be a good resisitor to use in this setup? and how do the resistors affect piezos?

thanks

 

[Inductor]

Here are some notes on piezos crossovers.
Using piezo tweeters wisely: a "how to" - AudioKarma.org Home Audio Stereo Discussion Forums
AudioRoundTable.com: Pi Speakers => Peizo tweeter use help

 

[godfrey]

Piezo tweeters are capacitive (in this case about 300nF), so it makes sense to me to use a crossover something like this:

 

[picowallspeaker]

Aren't piezos like supertweeter ? Or at least, in hi-fi I think they should be used like supertw ...
There's a design that uses a Ciare pt 383 as a regular tweeter and a Motorola
piezo, used above 10 KHz ( well, the Ciare tw is not 'regular', being mid-hi sensitivity and having a big dome ...)

So, the midrange...

 

[Fast Eddie D]

Piezo tweeters are capacitive (in this case about 300nF), so it makes sense to me to use a crossover something like this:

Bingo. Cookie cutter off the shelf crossovers will not provide the desired results with a piezo tweeter.

 

[godfrey]

Using just a single resistor in series with the tweeter doesn't help the tweeter at all, it just protects the amp from possible instability at ultrasonic frequencies. You can use a piezo tweeter like that, but it's better to use a proper crossover as shown above. That keeps the bass and most of the midrange out of the piezo, thereby improving power handling and reducing distortion.

 

[godfrey]

Aren't piezos like supertweeter ?

The one the OP linked to claims a frequency response of "1800-30000 Hz", but a lot will depend on the horn it's used with.

 

[picowallspeaker]

The piezo must have a Bessel-Chebichev nature, I suppose

 

[godfrey]

Huh?

 

[picowallspeaker]

Uh ?I was just checking : the Motorola KSN1016 is similar to what i thought ( 94 dB/W/m , 3k5-27 KHz ) and the Goldwood must be similar to the KSN1025 which is 90 dB and 1k8-30 KHz frequency response ( indeed ...my question was about power response ratio )