A piezo tweeter made by a good manufactor, CTS,Motorola
handles between 30 w rms-100w rms,depending on the model.
Also the Powerline series handle 400w music [by Tungsten bulb and PTC resistor, protection].
What i'm wondering is why do most piezo tweeters,although you can use them without a crossover; are used with a 2w 22 ohm resistor or 20w/10w 8 ohm resistor[the white wirewound ceramic block type].
Is the resistor added to increase the power handling of the driver?
Is the resistor used to lower the sensitivity of the driver to match the bass driver?
Or is the resistor used to protect piezo from super high frequency resonance peaks that occur in modern amps.
By the way i've got 2x CTS powerline KSN1142 piezo tweeters protected to 400w,2x [2 watt, 22ohm] resistors,2x CTS KSN1151A abs horns,2x Eminence Beta 15 150w rms.
This is driven by a poweramp which is 2x 200w rms into 8 ohm.
And my application is small venue use.
Also as my piezo is 92 db 1w/1m and my bass driver is 98 db 1w/1m.As my bass driver is more efficent than the tweeter,shall i add a resistor to the bass driver,or is this not recommended,also do you think a Graphic Equaliser would help overcome the difference in sensitivity,if i boost the highs and leave the rest at flat postion.
handles between 30 w rms-100w rms,depending on the model.
Also the Powerline series handle 400w music [by Tungsten bulb and PTC resistor, protection].
What i'm wondering is why do most piezo tweeters,although you can use them without a crossover; are used with a 2w 22 ohm resistor or 20w/10w 8 ohm resistor[the white wirewound ceramic block type].
Is the resistor added to increase the power handling of the driver?
Is the resistor used to lower the sensitivity of the driver to match the bass driver?
Or is the resistor used to protect piezo from super high frequency resonance peaks that occur in modern amps.
By the way i've got 2x CTS powerline KSN1142 piezo tweeters protected to 400w,2x [2 watt, 22ohm] resistors,2x CTS KSN1151A abs horns,2x Eminence Beta 15 150w rms.
This is driven by a poweramp which is 2x 200w rms into 8 ohm.
And my application is small venue use.
Also as my piezo is 92 db 1w/1m and my bass driver is 98 db 1w/1m.As my bass driver is more efficent than the tweeter,shall i add a resistor to the bass driver,or is this not recommended,also do you think a Graphic Equaliser would help overcome the difference in sensitivity,if i boost the highs and leave the rest at flat postion.
Hi Bull,
I expect the resistor is to match the output level to the other drivers which are normally much less efficient than the tweeter. Otherwise the speaker would end up sounding really shrill.
Phil
I expect the resistor is to match the output level to the other drivers which are normally much less efficient than the tweeter. Otherwise the speaker would end up sounding really shrill.
Phil
Piezos present a capacitive load, so often the resistance
is a polite way of keeping the power amplifier from getting
unduly excited.
It does not much affect the level in the audio band.
The resistor actually will roll off the high frequency response,
and you might adjust this down as low as 2 ohms or so
if you find that it improves the sound.
is a polite way of keeping the power amplifier from getting
unduly excited.
It does not much affect the level in the audio band.
The resistor actually will roll off the high frequency response,
and you might adjust this down as low as 2 ohms or so
if you find that it improves the sound.
Bull:
We have had discussions on Piezos before. Here a few links to previous discussions, as well as an important "Application Note" from Motorola.
http://www.ctscorp.com/pzt/speakerappnote.htm#hints
http://www.diyaudio.com/forums/showthread.php?threadid=3005&highlight=piezo
http://www.diyaudio.com/forums/showthread.php?threadid=2978&highlight=piezo
If you hook up 2 piezos rated at 92 dB @ 2.83V/1 Meter together in parallel, (+ to +, - to -), then you have a unit that plays at 98 dB @ 2.83V/1 Meter.
The KSN 1165A has a nice response for this purpose. Goes down to 2,000 Hz. And they are not expensive.
We have had discussions on Piezos before. Here a few links to previous discussions, as well as an important "Application Note" from Motorola.
http://www.ctscorp.com/pzt/speakerappnote.htm#hints
http://www.diyaudio.com/forums/showthread.php?threadid=3005&highlight=piezo
http://www.diyaudio.com/forums/showthread.php?threadid=2978&highlight=piezo
If you hook up 2 piezos rated at 92 dB @ 2.83V/1 Meter together in parallel, (+ to +, - to -), then you have a unit that plays at 98 dB @ 2.83V/1 Meter.
The KSN 1165A has a nice response for this purpose. Goes down to 2,000 Hz. And they are not expensive.
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