Hello All,
1. I am considering buying a pair of 2-way PA speakers which use a piezoelectric tweeter and a 94 dB sensitive wide band 12" driver. I have experienced the 12" drivergoing well up to 11,000 hz when used alone, so i suppose that in the 2-way configuration the system would be without any inductor in series with the 12" wide band.
Is it possible to use a 2 watts/channel amplifier to drive these speakers in a 16' x 22' living room?
2. The same question for a pair of 2-way PA speakers which use a 2nd order crossover for both drivers?
Some guidance from you all would be greatly helpful in proceeding with the decision.
Thanks in advance! 🙏
Sincerely,
sujat
1. I am considering buying a pair of 2-way PA speakers which use a piezoelectric tweeter and a 94 dB sensitive wide band 12" driver. I have experienced the 12" drivergoing well up to 11,000 hz when used alone, so i suppose that in the 2-way configuration the system would be without any inductor in series with the 12" wide band.
Is it possible to use a 2 watts/channel amplifier to drive these speakers in a 16' x 22' living room?
2. The same question for a pair of 2-way PA speakers which use a 2nd order crossover for both drivers?
Some guidance from you all would be greatly helpful in proceeding with the decision.
Thanks in advance! 🙏
Sincerely,
sujat
It should work as long as you don't want to play loud, uncompressed recordings of impulsive sounds. Does the piezo tweeter have a series resistor and is the impedance of the loudspeaker in accordance with what the amplifier can drive?
It s better to put at least a capacitor in serial with the piezo tweeter, from experience.
Otherwise there will be some overlapping in the reproduction and the frequencies at say 5-10Khz
will be reproduced by both speaker, not counting that the tweeter will be uselessly fed relatively low
frequencies wich could destroy it, dont count only on its supposed impedance increasing in the lower
part of the register.
Otherwise there will be some overlapping in the reproduction and the frequencies at say 5-10Khz
will be reproduced by both speaker, not counting that the tweeter will be uselessly fed relatively low
frequencies wich could destroy it, dont count only on its supposed impedance increasing in the lower
part of the register.
A piezo tweeter is capacitive except near its resonance frequency, so don't you just create a capacitive attenuator (voltage divider) with a series capacitor?
No, because the impedance of the capacitor is low at the higher range of the spectrum, it s negligible quantity
compared to the tweeter s impedance, beside in this case the woofer has large bandwith up to 11Khz, he can
use a relatively high cut off frequency.
FTR the piezo tweeter of my Roland Cube 60 for keyboards busted despite a 33R resistance in serial that was implemented
by Roland, i replaced it with a Motorola and did use a capacitor in serial and removed the resistance, it worked well and never failed despite a severe treatment as in some songs i used a distorsion pedal to approach the sound of a fuzzed guitar when doing solos, you can imagine the amount of high frequencies it endured with quasi square waves.
Edit : I also had the belief that they were resistant after reading some technical reviews, but in practice
I witnessed scores of piezos that were destroyed, these are actually much less robust than what is told here
and there.
compared to the tweeter s impedance, beside in this case the woofer has large bandwith up to 11Khz, he can
use a relatively high cut off frequency.
FTR the piezo tweeter of my Roland Cube 60 for keyboards busted despite a 33R resistance in serial that was implemented
by Roland, i replaced it with a Motorola and did use a capacitor in serial and removed the resistance, it worked well and never failed despite a severe treatment as in some songs i used a distorsion pedal to approach the sound of a fuzzed guitar when doing solos, you can imagine the amount of high frequencies it endured with quasi square waves.
Edit : I also had the belief that they were resistant after reading some technical reviews, but in practice
I witnessed scores of piezos that were destroyed, these are actually much less robust than what is told here
and there.
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I would suggest it depends upon the quality of the 12" driver and the Piezo.
I have PA speakers in a room with 12" Eminence Beta 12s, Motorola KSN1038A tweeter, can't recall the crossover but I used an air core inductor for the 12".
The 12" needs some bass EQ, but actually the sound is very good, sweet treble and a lot of impact and realism as the 12" can move some air.
Currently it's driven from 150W MOSFET amps each side, but they are pretty sensitive - just make sure the box is good, for most 12" PA speakers the box may need to be quite big.
I have PA speakers in a room with 12" Eminence Beta 12s, Motorola KSN1038A tweeter, can't recall the crossover but I used an air core inductor for the 12".
The 12" needs some bass EQ, but actually the sound is very good, sweet treble and a lot of impact and realism as the 12" can move some air.
Currently it's driven from 150W MOSFET amps each side, but they are pretty sensitive - just make sure the box is good, for most 12" PA speakers the box may need to be quite big.
Oh and look up online about crossovers to piezos, a little knowledge and research is useful for them. They are actually very low distortion - that is, the good ones, less fatiguing than domes at volume sometimes.
The piezotweeter itself is also a capacitor, so if the impedance of the series capacitor is negligible compared to that of the tweeter at high frequencies, the same holds at low frequencies.
The series resistor is mainly there to keep the amplifier stable, as far as I know.
High level BASS is what blows piezo tweeters. Overexcursion results, literally ripping the lead wires off the piezo disk. It will also distort the high frequencies being reproduced at the same time. So if you have a limited amount of power (2 watts, or even 60) the piezo is safe without a crossover. You won’t drive them to damage or severe distortion. They SOUND better across the board with a proper 4th-order-acoustic crossover between woofer and tweeter, but then again anything does. Most low end PA speakers don’t have “real”, proper slope crossovers on both woofer and tweeter - even with regular VC-driven tweeters. Only a high pass of some sort on the tweeter to prevent damage.
These low end PA speakers, even with no crossover on the tweeter do ok in PA duty if the high level low freqency is being handled by subwoofers, or as instrument amps where it isn’t trying to pump out bass.
These low end PA speakers, even with no crossover on the tweeter do ok in PA duty if the high level low freqency is being handled by subwoofers, or as instrument amps where it isn’t trying to pump out bass.
Agree but the total impedance at relatively low frequencies being high the amp loading will be low as well, FI is the respective
impedances at say 5KHz is 4R for the capacitor and 8R for the total impedance will be 12R at this frequency.
At high frequencies the loading will be high but will be limited by the devices parasistic resistance that is in serial with
the capacitance as well as the parasistic inductance of the capacitor assuming it s an electrochemical capacitor.
As said both the capacitor and the tweeter have parasistic resistance in serial, even high capacitances like 1000uF
exhibit this behaviour, to wich should be added the parasitic inductance of the capacitor, that s why single supply rail
amps that use a big capacitor in serial with the speaker do not need an inductance in serial with the speaker to be stable
since it s already built in within the decoupling capacitor.
well, where are you gonna sit?, at what distance? is 97db at 2w, but minus 3db for every meter of distance you add. in a room a find something around 75db to be a pleasant room volume, and 85 is considered loud, and everything above to be too loud neighbor annoying levels. 2w is enough for the guys with low power tube amps.
I would expect that you have enough power. Try this test to find out
https://www.diyaudio.com/community/...h-voltage-power-do-your-speakers-need.204857/
Brian
https://www.diyaudio.com/community/...h-voltage-power-do-your-speakers-need.204857/
Brian
That means you just made a capacitive attenuator that attenuates the signal to 2/3, about -3.5 dB, rather than a high-pass filter. For a first-order high-pass, you would have to shunt the piezotweeter with a resistor and put a capacitor in series with the combination (and possibly another resistor to keep the amplifier stable). At least that's the simplest solution I can think of.
Anyway, the thread starter is unlikely to blow up a PA tweeter with a 2 W amplifier.
It's essentially a piezoelectric ceramic capacitor with a diaphragm and a horn attached to it.
A standard 22uF electrochemical capacitor has an ESR that is in the 7-30R range, a 100uF is at 2-7R, low ESR
models of the same capacitance are 1-5R and 0.3-1.6R respectively and this value increase with frequency, so a standard electrochemical has way enough ESR to balance its capacitance, there s not even the need of a resistance in serial.
models of the same capacitance are 1-5R and 0.3-1.6R respectively and this value increase with frequency, so a standard electrochemical has way enough ESR to balance its capacitance, there s not even the need of a resistance in serial.
2W average is credible, but most of the music I listen to has a fair amount of dynamic range.
Also it depends on background noise, I live in a detached house in a fairly quiet place so there is no traffic noise or 'people next door' to interfere with the quiet bits of the music.
If you listen to rock music which is produced to be listened to in a car, you will be OK with quite low power in a quiet place.
If you listen to classical music with lots of quiet passages, against the background noise of traffic or a washing machine in the next room, or even a computer fan on your desk, you may want more watts for the loud passages.
There are plenty of cheap 20W (or more) amps available. Don't rule out the 'class D' amps either.
Maybe better to have class D in its comfort zone than Class A clipping?
The other thing is, if you like the music, you will ignore imperfections in the reproduction.
Also it depends on background noise, I live in a detached house in a fairly quiet place so there is no traffic noise or 'people next door' to interfere with the quiet bits of the music.
If you listen to rock music which is produced to be listened to in a car, you will be OK with quite low power in a quiet place.
If you listen to classical music with lots of quiet passages, against the background noise of traffic or a washing machine in the next room, or even a computer fan on your desk, you may want more watts for the loud passages.
There are plenty of cheap 20W (or more) amps available. Don't rule out the 'class D' amps either.
Maybe better to have class D in its comfort zone than Class A clipping?
The other thing is, if you like the music, you will ignore imperfections in the reproduction.
2W average is actually pretty loud - by the time you drown out a washing machine with it your neighbors (or the cops) are already knocking on your door. But that does require a 20 watt amplifier. A 2W amp might get you to .2 watts average, with compressed rock/pop.
A 12” PA speaker will be a good 10dB louder (for a given watts) compared to a typical home speaker and 20dB louder than a Bluetooth smart speaker, which trades off even more sensitivity and add tons of EQ. But the PA speaker is bigger, and still thin in the bass because that kind of speaker just isn’t made to put out much low end. If you roll your own, you can make other trades in the design that just aren’t favorable commercially, and end up with a large (5 or 10 cubic foot) box that is effing loud on a 2 watt tube amp and still give you 40 Hz bass. Think 2x15 or 18, not 12”. And no, you don’t need $400 woofers to do it. Just the right ones.
A 12” PA speaker will be a good 10dB louder (for a given watts) compared to a typical home speaker and 20dB louder than a Bluetooth smart speaker, which trades off even more sensitivity and add tons of EQ. But the PA speaker is bigger, and still thin in the bass because that kind of speaker just isn’t made to put out much low end. If you roll your own, you can make other trades in the design that just aren’t favorable commercially, and end up with a large (5 or 10 cubic foot) box that is effing loud on a 2 watt tube amp and still give you 40 Hz bass. Think 2x15 or 18, not 12”. And no, you don’t need $400 woofers to do it. Just the right ones.
Thank you for your kind contribution, Marcel. 🙏
The manufacturer mentions nothing about whether they use anything in series with the piezo tweeter.
Yes, impedance wise, the speakers are rated at 8 ohms nominal, and are compatible.
Unfortunately, Wahab, this is a local manufacturer who specifies nothing about the crossover, nor do they offer any impedance plot for the piezo. How then may one determine the value of the capacitor for a 1st order point around 11,000 hz?
Your response feels quite encouraging! In fact, the large format 500 cm^2 of Sd is what tempts me.... their effortless delivery is engaging. Thank you for your kind contribution, Globulator. 🙏