Car Audio

[zafeniak]

Hi Guys,

I'm a new member so hello to all!

I recently purchased a honda accord euro 2005 Lux and planning to upgrade the the audio system.

I am wanting to put in a JL 13w1v2 4-ohm in a sealed enclosure.

On the JL website, they recommend a box enclosure of 1.5 ft3 (or 42.5 L)

However, when I plugged the specs of the sub in to a website calculator, it came up with 2.5 ft3. I sued the following website:
http://www.diyaudioandvideo.com/Calculator/Box/


Can anyone who knows their stuff about subs shed some light onto what's happened and how big the enclosure needs to be?

Cheers

(Below are the specs for the sub as well as the calculation from the website:)

Calculation from website:
Sealed Box
Vas = 6.131 ft3
fs = 20.9 Hz
Qts = 0.384
Qtc = 0.707
Dimensions
________________________________________
Vb = 2.57 ft3 = 72.65 lts
= L x W x H
f3 = 38.49 Hz
fb = 38.48 Hz

Vb: Speaker Box Internal Volume
f3: 3dB Cutoff Frequency
fb: Enclosure Resonant Frequency


Speaker specs:


13W1v2 DRIVER SPECIFICATIONS
13W1v2-4 13W1v2-8

Free Air Resonance (Fs): 20.9 Hz 21.9 Hz
Electrical “Q” (Qes): 0.406 0.462
Mechanical “Q” (Qms): 6.936 6.774
Total Speaker “Q” (Qts): 0.384 0.433
Equivalent Compliance (Vas): 6.131 cu. ft. / 173.51 liters 5.982 cu. ft. / 169.29 liters

One-Way, Linear Excursion (Xmax)*: 0.475 in. / 12.1 mm 0.475 in. / 12.1 mm
Reference Efficiency (no): 0.375% 0.369%
Efficiency (1W/1m)**: 87.71 dB SPL 87.65 dB SPL
Effective Piston Area (Sd): 105.774 sq. in. / 0.0682 sq. m. 105.774 sq. in. / 0.0682 sq. m.
DC Resistance (Re): 4.114 ohm 6.803 ohm
Nominal Impedance (Znom): 4 ohm 8 ohm
Thermal Power Handling (Pt): 350W 350W
Driver Displacement: 0.05 cu. ft. / 1.42 liters 0.05 cu. ft. / 1.42 liters
Net Weight: 11.21 lbs. / 5.08 kg 11.21 lbs. / 5.08 kg
* Xmax specifications are derived via one-way voice coil overhang method with no correction factors applied.
** Efficiency (1W/1m) is not an accurate indicator of a subwoofer's output capability and should not be used as a comparison to other subwoofers to determine which one is "louder".
SUBWOOFER RECOMMENDED SEALED ENCLOSURES
Volume
(net int.)
External Dimensions
(Width x Height x Depth)
F3
(Hz)
Fc
(Hz)
Qtc
13W1v2-4 1.5 cu. ft.
42.5 litres
18.5 in. x 16.5 in. x 12 in.
470 mm x 419 mm x 305 mm
40.7 38.8 0.713
13W1v2-8 1.75 cu. ft.
49.5 litres
18.5 in. x 16.5 in. x 13.75 in.
470 mm x 419 mm x 349 mm
38.0 39.0 0.772

[arverson]

modeled the specs in winisd. for a sealed box id make it around ~1.8 cuft NET / 50 L NET (you can give-or-take a few liters, wont make too much difference). gives a balanced response that gives a good middle-ground between accuracy & efficiency.

btw net = box volume after sub displacement & bracing (if any). so make it a 2 cuft / 56 L GROSS if thats the answer you wanted.

[zafeniak]

modeled the specs in winisd. for a sealed box id make it around ~1.8 cuft NET / 50 L NET (you can give-or-take a few liters, wont make too much difference). gives a balanced response that gives a good middle-ground between accuracy & efficiency.

btw net = box volume after sub displacement & bracing (if any). so make it a 2 cuft / 56 L GROSS if thats the answer you wanted.

Why is there sch large inconsistencies between the programs themselves and the maufacturer's specs?

[arverson]

because its easier for manufacturers to sell a sub if they say its suits a smaller enclosure, instead of recommending a more 'optimum' one. they mention a smaller size to entice newcomers, just to let em know 'hey get this sub and you wont need a large box'. and that recommendation isnt always in the best interest of pure sound quality, or having the best efficiency while playing lower. basically, its perfect marketing.

[zafeniak]

Could someone please run these specs through WinISD for a ported enclosure? The port and and enclosure itself in the manual appear to small (Box is 1.75 cf and port is 7.6cm D x 35cm L)?

Thanks in advanve