B315 Low Speaker Plans

Hey .... is there anything that can help the size of the box like this .....?

cc35_cfs_page.jpg
 
Let me see if I understand your question.
It's your idea to make similar speakers knowing the external size of the speaker enclosure and you want a bass reflex system with 3x15" drivers, or I'm missing something?!
emPad B315 Low Frequency Speaker System
Low frequency transducers 3x15" Drivers
Low frequency cabinet operating dimensions in mm 1090Hx490Wx500D
B315 | emPad Professional Concert Loudspeaker Systems
 

djk

R.I.P
2001-02-04 4:23 am
USA
"In what part, I didn't noticed?"

The combination of size, efficiency, and frequency response are not possible.

A 2 cu ft 2nd order sealed box with an F3 of 30hz can only be 0.18% efficient (84.55dB).
A 2 cu ft 4th order vented box with an F3 of 30hz can only be 0.36% efficient (87.56dB).
A 2 cu ft 6th order vented box with an F3 of 30hz can only be 0.90% efficient (91.54dB).

The efficiency of the 6th order is midband only, in the lowest 1/2 octave of the LF there is 6dB of boost applied (so it is not violation the laws of physics as it seems to do).
 
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djk

R.I.P
2001-02-04 4:23 am
USA
"are you sure we are in the same page??? "

You aren't.

Every time you double the box volume you can add 3dB.

Your 9.4308 is gross, the 2 cu ft spec is net. Even if the net on your box was 8 cu ft (and it isn't even that big) that would only add 6dB to the numbers for the 2 cu ft box.

91.54dB + +6dB = 97.54dB

108dB is pure fiction.
 
108dB is pure fiction.
Maybe it is, I'm not saying it's not... bear with me!
(Having in mind I don't know what type of system/drivers they are using, do you?!) :)

1. Let's look at 18Sound 15NLW9500 (3x)
I'm using net vol. 245L = 8.65ft³
OB system (not the case):
2Pi SPL = 106.4 dB/2.83V/m
4Pi SPL = 102.4 dB/2.83V/m
BR system:
2Pi SPL = 102.3 dB/2.83V/m
4Pi SPL = -
max. SPL: 1.00 m = 135.6 dB

Announced emPad B315 Specs:
System sensitivity @ 1m/1w = 108 dB
Maximum sound pressure level = 138 dB

The difference for this driver system sensitivity vs. the emPad is accentuated but the max SPL is not.
I can only say that specs where taken with another driver/system or at a high frequency, from my point of view, were output peaks.
 
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djk

R.I.P
2001-02-04 4:23 am
USA
"(Having in mind I don't know what type of system/drivers they are using, do you?!)"

I don't know of any brand of drivers that can violate the laws of physics, do you?

Paralleling three drivers with 2.83V is not 1W either, it's 3W (+4.77dB). Even giving you that cheat it's still not 108dB.

I'll run the numbers on that driver when I get home, the DCR is only 1.63Ω for three drivers in parallel, a wicked load.
 
I don't know of any brand of drivers that can violate the laws of physics, do you?
...
I'll run the numbers on that driver when I get home, the DCR is only 1.63Ω for three drivers in parallel, a wicked load.
I'm sorry if I caught you in a bad mood... :D

15NLW9500
18Sound 15NLW9500 (3x) Re = 1.63Hz
18Sound 15NLW9500 (3x) 2.0 Ohms @ 34.2Hz
18Sound 15NLW9500 (3x) 1.8 Ohms @ 327.2Hz

For your information the brand new and "ridiculous" Wilson Alexia is (imp/min) 1.8ohm @ 85Hz with an EPDR of 0.9ohm at 65Hz.

Now if you are not happy yet (or mad), look at this DVC driver from Sweden (I know it's DC resistance is 1,27 ohm parallel) with Sensitivity, 1 W/1 m = 99,9 dB.
DLS SP15
 

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djk

R.I.P
2001-02-04 4:23 am
USA
"I'm sorry if I caught you in a bad mood... "

I've been trying to avoid calling you mentally challenged, it's hard though. It does seem like you're being obtuse because I'm not telling you what you want to hear.

A McIntosh MC2300 can drive a 0.25Ω load in mono ( I had a club install driving eight 15s with one), but most amps won't sound good or run for long at 2Ω or lower.

Driver Properties
Name: 15NLW9500
Type: Standard one-way driver
Company: Eighteen Sound
No. of Drivers = 3
Mounting = Standard
Wiring = Parallel
Fs = 35 Hz
Qms = 6.7
Vas = 163 liters
Cms = 0.139 mm/N
Mms = 149.2 g
Rms = 4.897 kg/s
Xmax = 9 mm
Xmech = 18.5 mm
P-Dia = 340.4 mm
Sd = 910 sq.cm
P-Vd = 0.819 liters
Qes = 0.34
Re = 4.9 ohms
Le = 0.8 mH
Z = 6 ohms
BL = 21.75 Tm
Pe = 1000 watts
Qts = 0.324
no = 1.982 %
1-W SPL = 95.12 dB
2.83-V SPL = 97.25 dB
-----------------------------------------
Box Properties
Name:
Type: Vented Box w/ Active HP Filter
Shape: Prism, square
Vb = 7.413 cu.ft
Fb = 32.45 Hz
QL = 5.667
F3 = 35.29 Hz
Fill = minimal
No. of Vents = 1
Vent shape = round
Vent ends = one flush
Dv = 11.22 in
Lv = 24.28 in
-----------------------------------------
Active 12 dB/oct. HP Filter
Fx = 34.72 Hz
Qx = 1.93

OK, what can it do?

Ignoring power compression, with 3KW input at 50hz it will produce about 131dB in 2Pi, and use almost all the linear x-max available. It's 102.2dB/2.83V/1M (three drivers), or 96.2dB/1W/1M into its actual 2Ω impedance. Impedance is a solid 2Ω below 150hz, with a minimum of 1.64Ω around 300hz.

108dB/W?

I think not.

With the port the net volume will be in excess of 9 cu ft, and you would need to figure out the bracing as well as the volume displaced by the drivers, etc.
 
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