Dual 15" Subwoofer project complete - Page 2 - diyAudio
 Dual 15" Subwoofer project complete
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 15th January 2013, 03:00 AM #11 diyAudio Member     Join Date: Feb 2006 Location: Cascais 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 Attached Images __________________ Uriah Heep - Return To Fantasy 1975
 15th January 2013, 05:52 PM #12 diyAudio Member     Join Date: Feb 2006 Location: Cascais 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 __________________ Uriah Heep - Return To Fantasy 1975
diyAudio Member

Join Date: Jan 2008
Quote:
 Originally Posted by Inductor 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

diyAudio Member

Join Date: Feb 2006
Location: Cascais
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
Attached Images
 DIYAUDIO SUBS 2xB&C 15 PS 100_output.jpg (78.4 KB, 253 views) DIYAUDIO SUBS 2xB&C 15 PS 100_displacement_xmax.jpg (158.3 KB, 242 views) DIYAUDIO SUBS 2xB&C 15 PS 100_spl.jpg (159.2 KB, 235 views)

 16th January 2013, 06:59 PM #15 diyAudio Member     Join Date: Jan 2008 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
 16th January 2013, 11:19 PM #16 diyAudio Member     Join Date: Nov 2003 Location: iowa 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.
diyAudio Member

Join Date: Jan 2008
Quote:
 Originally Posted by norman bates 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
Attached Images
 28,38 Fb.png (163.1 KB, 59 views)

 18th January 2013, 08:55 PM #18 diyAudio Member     Join Date: Nov 2003 Location: iowa 28hz tuning sounds better than 40hz to my ears, smoother. Less thunk thunk sounds. Hard to explain.
diyAudio Member

Join Date: Jan 2005
Location: NYC
Quote:
 Originally Posted by twin turbo I've updated my blog with my latest project. Joseph Crowe's DIY Speaker Building Blog: B&C Sub 215 (Dual 15") project
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?

diyAudio Member

Join Date: Mar 2012
Quote:
 Originally Posted by mikehende 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
 B&C%20Sub%20215%201.jpg (217.4 KB, 90 views) 330.jpg (26.6 KB, 69 views)

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