I wanted to make some speakers, but there are several very nonstandard concepts jumbled all in there together, so I wanted to consult the experts to see if I am totally insane.
Firstly, the speakers are mainly for small-stage PA use, like cofeehouse-style guitars, vocals, poetry and some background music. 100 watts a side at 94-96dB efficiency would be fine. I also want to take them to the Burning Man Festival and use them in my themecamp, so they have to be reasonably rugged. And cheap.
First crazy concept: I want to use a short vertical line of 4 drivers either 4", 4.5" or 5.5" tops with a single piezo tweeter. The smaller diameter will let me cross over higher (3.5K?) so essentially all the voice band will be carried by the small diameter drivers for maximum clarity. However, the near-to-far-field transition will occur in the listening area, how screwed up is that really?
Second crazy concept: I want to use a sealed box with Q of 1.0, and an f3 about 100. Then I will add a first-order Butterworth electronic hipass xover with q= .707, so (if I am right) box Q of 1 times crossover Q of .707 equals a composite third order Butterworth highpass response with Q=.707. Am I right? Can anybody tell me, if the box -3dB point is 100 Hz, what frequency should I set the electronic crossover for, and what new -3dB frequency will I end up with for my composite response?
Of course I will use a subwoofer with a matching 3rd order Butterworth lowpass for the bottom two octaves.
Third crazy concept: I want do the same for the piezo tweeter, adding a first-order R-C network to turn the natural second-order 3.5 K acoustic highpass into a third-order composite Butterworth highpass, which should also increase power handling in the tweeter somewhat. Any hints how to do that?
Fourth crazy concept: Instead of arranging the drivers TMMMM, I want to arrange them MTMMM. Why? The Butterworth has a -15 degree polar tilt when arranged TMMMM. It has a zero degree polar tilt if you arrange it MMTMM like the D'Appolito arrangement. A little downward tilt is actually good in a PA setup when the cabinets are typically over head level, so I figure arranging it MTMMM will give me some, but less than 15 degrees, of downward polar tilt. Sort of a semi-D'Appolito. Any comments?
P.S. I am thinking about Dayton 5.25" treated paper drivers with a very mellow FR curve, also the Dayton aluminum-cone woofers but they seem very peaky around 10K, also some little Goldwood 4" poly-mica cone drivers. Since part of the use might be outside, I really worry about moisture, though I've seen big sound companies field what look like treated paper drivers at big outdoor events; if it rains they just throw a tarp over it and don't seem to worry too much. How good is treated paper at resisting moisture anyway?
OK experts: please have at it and tell me just how insane I am!
Thanks
Firstly, the speakers are mainly for small-stage PA use, like cofeehouse-style guitars, vocals, poetry and some background music. 100 watts a side at 94-96dB efficiency would be fine. I also want to take them to the Burning Man Festival and use them in my themecamp, so they have to be reasonably rugged. And cheap.
First crazy concept: I want to use a short vertical line of 4 drivers either 4", 4.5" or 5.5" tops with a single piezo tweeter. The smaller diameter will let me cross over higher (3.5K?) so essentially all the voice band will be carried by the small diameter drivers for maximum clarity. However, the near-to-far-field transition will occur in the listening area, how screwed up is that really?
Second crazy concept: I want to use a sealed box with Q of 1.0, and an f3 about 100. Then I will add a first-order Butterworth electronic hipass xover with q= .707, so (if I am right) box Q of 1 times crossover Q of .707 equals a composite third order Butterworth highpass response with Q=.707. Am I right? Can anybody tell me, if the box -3dB point is 100 Hz, what frequency should I set the electronic crossover for, and what new -3dB frequency will I end up with for my composite response?
Of course I will use a subwoofer with a matching 3rd order Butterworth lowpass for the bottom two octaves.
Third crazy concept: I want do the same for the piezo tweeter, adding a first-order R-C network to turn the natural second-order 3.5 K acoustic highpass into a third-order composite Butterworth highpass, which should also increase power handling in the tweeter somewhat. Any hints how to do that?
Fourth crazy concept: Instead of arranging the drivers TMMMM, I want to arrange them MTMMM. Why? The Butterworth has a -15 degree polar tilt when arranged TMMMM. It has a zero degree polar tilt if you arrange it MMTMM like the D'Appolito arrangement. A little downward tilt is actually good in a PA setup when the cabinets are typically over head level, so I figure arranging it MTMMM will give me some, but less than 15 degrees, of downward polar tilt. Sort of a semi-D'Appolito. Any comments?
P.S. I am thinking about Dayton 5.25" treated paper drivers with a very mellow FR curve, also the Dayton aluminum-cone woofers but they seem very peaky around 10K, also some little Goldwood 4" poly-mica cone drivers. Since part of the use might be outside, I really worry about moisture, though I've seen big sound companies field what look like treated paper drivers at big outdoor events; if it rains they just throw a tarp over it and don't seem to worry too much. How good is treated paper at resisting moisture anyway?
OK experts: please have at it and tell me just how insane I am!
Thanks
For bass to mid recommend 4th order L/R which is two
2nd order butterworths cascaded, - 6dB at crossover.
You'd need two cascaded 2nd order butterworths for the bass,
but only one for the mid if you go for sealed Q = 0.7 and use
this as one section, c/o point is -3dB of the box.
I'll let others comment on the rest.
sreten.
2nd order butterworths cascaded, - 6dB at crossover.
You'd need two cascaded 2nd order butterworths for the bass,
but only one for the mid if you go for sealed Q = 0.7 and use
this as one section, c/o point is -3dB of the box.
I'll let others comment on the rest.
sreten.- Status
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