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Old 15th January 2013, 03:00 AM   #11
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This is the alignment used
2xB&C 15 PS 100, VB = 300.0 L, FB = 40.0 Hz, 97.5 dB2.83Vm.
F3=36Hz F6=33Hz F12=28Hz F24=20Hz
30 Hz -13.5 mm cone displacement

I would prob. go to this one (lower freq.).
2xB&C 15 PS 100, VB = 300.0 L, FB = 32.3 Hz, 97.5 dB2.83Vm.
30 Hz -4 mm cone displacement / 25 Hz - 13.5 mm.
F3=33Hz F6=29Hz F12=24Hz F24=17Hz
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Old 15th January 2013, 05:52 PM   #12
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Default Box Volume

To be fair the internal volume is smaller than the projected 300L, closer to the ideal size/int. volume for both drivers. I calculate each (x2) handle box to be ~23.6 centimeters by 20 centimeters by 12 centimeters. (= 5.664 liters)
Fb/Internal Volume 300 L - 12 L = ~282L
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Old 16th January 2013, 05:25 PM   #13
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Quote:
Originally Posted by Inductor View Post
This is the alignment used
2xB&C 15 PS 100, VB = 300.0 L, FB = 40.0 Hz, 97.5 dB2.83Vm.
F3=36Hz F6=33Hz F12=28Hz F24=20Hz
30 Hz -13.5 mm cone displacement
Inductor,

The B&C 15PS100 has only 8mm Xmax, how many watts/volts does it take for a pair to hit that above Fb in a 300L 40 Hz Fb box?

Art
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Old 16th January 2013, 05:51 PM   #14
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Quote:
how many watts/volts does it take for a pair to hit that...
weltersys,
linking the new pics for the DIYAUDIO SUBS 2xB&C 15 PS 100
VB = 288.0 L, FB = 40.0 Hz, 97.5 dB/2.83V/m
F3=36Hz F6=33Hz F12=28Hz F24=20Hz
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Old 16th January 2013, 06:59 PM   #15
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Inductor,

My Portuguese is no good, but it looks like with 60.42 volts (912 watts in to four ohms) this design will hit Xmax at about 53.6 Hz at 128.1 dB, power compression ignored.
That's 4 dB better than my guess in post #3 which was based on B&C's 100L 40Fb single driver cabinet which shows a excursion limit maximum 1 meter SPL of only 118 dB, the extra 50L per driver makes a difference!

Thanks,
Art
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Old 16th January 2013, 11:19 PM   #16
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yea, tuned around 40hz (assuming not much going in below that), you can hit serious serious spl's with 8mm drivers............

But based on that driver and box, you are 9db down around 30hz.
I'd call that a deep woofer, not a subwoofer.
But really good for a PA subwoofer (high spls for hours).

In a home for a subwoofer looking for depth extension, I'd like to see ported F3 at or below 27hz........... maybe 30hz F3 for a sealed.

Others like even lower F3's, but I'd rather not trade ported F3/tuning of 20hz for the excursion and the more often information around 30hz.

Then again a 3ft3 20hz ported epic 12 still stays under its xmax of 23mm with 600 watts (wow) from 20hz upwards.

Norman

Last edited by norman bates; 16th January 2013 at 11:21 PM.
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Old 18th January 2013, 02:57 PM   #17
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Originally Posted by norman bates View Post
yea, tuned around 40hz (assuming not much going in below that), you can hit serious serious spl's with 8mm drivers............

But based on that driver and box, you are 9db down around 30hz.
I'd call that a deep woofer, not a subwoofer.
But really good for a PA subwoofer (high spls for hours).

In a home for a subwoofer looking for depth extension, I'd like to see ported F3 at or below 27hz........... maybe 30hz F3 for a sealed.

Norman
Norman,

One can certainly afford to go much lower in a home theater than a PA situation where transport, storage and set up space dictate cabinet size, and in smaller venues, power is often inadequate.

The chart below illustrates what going from a 38 Hz Fb to a 28 Hz tuning in the same box size does (driver is a BC18SW115-4)-it would take almost two times the drivers, boxes and power for the 28Hz Fb to reproduce the 40-55 Hz range where most of the low stuff in pop music lives.
The 28 Hz tuning actually is only louder than the 38Hz tuning below 34 Hz, very near the low B on a five string bass.
I have found 35-38 Hz tunings to be the best compromise between output and extension now that the usual low string on a bass has gone from 41 to 31 Hz.

Art
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File Type: png 28,38 Fb.png (163.1 KB, 53 views)
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Old 18th January 2013, 08:55 PM   #18
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28hz tuning sounds better than 40hz to my ears, smoother. Less thunk thunk sounds. Hard to explain.
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Old 27th August 2013, 12:51 PM   #19
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Originally Posted by twin turbo View Post
Hello, I am looking into building my own dual 15 reflex cab, I looked at Joseph's link for I am not seeing the plan for this cab, can you help please? Also, since this is a BNC design, would I be able to other woofers like Eminence kilomax Pro?
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Old 27th August 2013, 01:30 PM   #20
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Originally Posted by mikehende View Post
Hello, I am looking into building my own dual 15 reflex cab, I looked at Joseph's link for I am not seeing the plan for this cab, can you help please? Also, since this is a BNC design, would I be able to other woofers like Eminence kilomax Pro?
I guess B&C has updated their website and the link no longer works.
I've attached the plans for you.

In order to verify that the Eminence Kilomax will work you'll have to model it in WinISD and see the resulting frequency response.

I've received countless compliments on how well this sub sounds from a sound quality standpoint. It has great pitch definition, very clean and tight sounding.
Attached Images
File Type: jpg B&C%20Sub%20215%201.jpg (217.4 KB, 67 views)
File Type: jpg 330.jpg (26.6 KB, 59 views)
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