Hi everyone,
My first post on this forum.
I'm planning to use full range drivers that are specified at 45Hz - 20kHz with Fs 45Hz, and I plan to use them full range with their obvious advantages.
Since they have Xmax 5mm and 30Watts RMS power handling with only moderate sensitivity of 88dB 1W/1m, I would like to try employing 3 of them in an array. By wiring them series/parallel, i.e. both series and parallel, it would substantially increase both the power handling and sensitivity for much greater SPLs with only a moderate decrease in system impedance making for an easy load for an amplifier.
I just wanted to know what the reultant speaker's system sensitivity would be. I believe there is a formula for it.
My first post on this forum.
I'm planning to use full range drivers that are specified at 45Hz - 20kHz with Fs 45Hz, and I plan to use them full range with their obvious advantages.
Since they have Xmax 5mm and 30Watts RMS power handling with only moderate sensitivity of 88dB 1W/1m, I would like to try employing 3 of them in an array. By wiring them series/parallel, i.e. both series and parallel, it would substantially increase both the power handling and sensitivity for much greater SPLs with only a moderate decrease in system impedance making for an easy load for an amplifier.
I just wanted to know what the reultant speaker's system sensitivity would be. I believe there is a formula for it.
Can you provide full specifications? You may have better results by using a rear loaded horn enclosure with a single driver rather than having to deal with the comb filtering effects of an array. Another possibility is to use two of them in a 1.5 arrangement where one driver is run full range and the other uses a low pass filter so that it only reproduces the bass. This would give some help in the low end where the driver is probably lacking the most and the comb filtering would not be a problem.
I'm afraid full range electrodynamic drivers have no sonic advantages, obvious or otherwise, and stacking more than one of them together will make even those properties of theirs that some people perceive as advantages vanish.
If such a multi-FR hydra
is ever created, a set of axial (?) and polar frequency responses will elucidate my point.
An externally hosted image should be here but it was not working when we last tested it.
is ever created, a set of axial (?) and polar frequency responses will elucidate my point.
The original poster should consider two configurations of his three drivers which may offer benefits. I assume that the three drivers are arrayed in the vertical plane as close as possible.
One configuration would be a two way design wherein the two outer drivers are connected in parallel (makes a 4.5 ohms impedance) for the lower frequency range and then crossed to the center driver which handles the upper frequency range. You would have a 6 dB improvement in the sensitivity for the lower band (3 dB from the second driver and 3 dB from cutting the impedance from 9 to 4.5 ohms). You also achieve double the power handling (30 to 60 watts) in the lower range which is where you generally wish to have more power handling. The upper frequency range would have the single center driver so you have 9 ohms and 30 watts power handling of a single driver. This arrangement would permit you to address any baffle step compensation (generally on the order of 6 dB more sensitivity is needed over the lower part of the band). Your crossover point also be low enough to eliminate comb line effects from the drivers (you would like less than a quarter to half wave length center-to-center spacing) for this factor.
The second configuration would be what is called a 1.5 way configuration wherein all three drivers contribute to the lower end performance of the speaker system. Thus the array of three drivers would yield 4.77 dB array gain but the interconnection method would need to be considered. Assume first the case wherein you connect all three drivers in parallel for a 3 ohms total impedance (assumes your amplifier can live with this impedance) which yields another 4.77 dB sensivitivy for a total of 9.54 dB sensitivity improvement for these drivers. Now if the two outer drivers are connected in parallel and then the center driver is connected in series with those two for a 13.5 ohms impedance. For 13.5 ohms you would have a loss in sensitivity of 1.76 dB so the net total sensitivity gain is only 4.77 -1.76 = 3 dB. The third way to connect these drivers is to series connect the outer two drivers (18 ohms) and then parallel that with the center driver for equivalent of 6 ohms. That has 1.76 dB improvement due to impedance sensitivity for a total of 4.77 + 1.76 = 6.53 dB.
The 1.5 way arrangements would all assume that you run the center driver full band while the outer drivers would be rolled off over the higher frequency range to prevent combing and to achieve baffle step if needed.
Equations are in my line array paper at:
http://audioroundtable.com/misc/nflawp.pdf
One configuration would be a two way design wherein the two outer drivers are connected in parallel (makes a 4.5 ohms impedance) for the lower frequency range and then crossed to the center driver which handles the upper frequency range. You would have a 6 dB improvement in the sensitivity for the lower band (3 dB from the second driver and 3 dB from cutting the impedance from 9 to 4.5 ohms). You also achieve double the power handling (30 to 60 watts) in the lower range which is where you generally wish to have more power handling. The upper frequency range would have the single center driver so you have 9 ohms and 30 watts power handling of a single driver. This arrangement would permit you to address any baffle step compensation (generally on the order of 6 dB more sensitivity is needed over the lower part of the band). Your crossover point also be low enough to eliminate comb line effects from the drivers (you would like less than a quarter to half wave length center-to-center spacing) for this factor.
The second configuration would be what is called a 1.5 way configuration wherein all three drivers contribute to the lower end performance of the speaker system. Thus the array of three drivers would yield 4.77 dB array gain but the interconnection method would need to be considered. Assume first the case wherein you connect all three drivers in parallel for a 3 ohms total impedance (assumes your amplifier can live with this impedance) which yields another 4.77 dB sensivitivy for a total of 9.54 dB sensitivity improvement for these drivers. Now if the two outer drivers are connected in parallel and then the center driver is connected in series with those two for a 13.5 ohms impedance. For 13.5 ohms you would have a loss in sensitivity of 1.76 dB so the net total sensitivity gain is only 4.77 -1.76 = 3 dB. The third way to connect these drivers is to series connect the outer two drivers (18 ohms) and then parallel that with the center driver for equivalent of 6 ohms. That has 1.76 dB improvement due to impedance sensitivity for a total of 4.77 + 1.76 = 6.53 dB.
The 1.5 way arrangements would all assume that you run the center driver full band while the outer drivers would be rolled off over the higher frequency range to prevent combing and to achieve baffle step if needed.
Equations are in my line array paper at:
http://audioroundtable.com/misc/nflawp.pdf
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