Help understanding he WinISD graph

[Villainstone]

Hi guys I am building a subwoofer enclosure for my vehicle. It will be installed in a Santa Fe trunk. The subwoofer is an Fi BL 12"

https://ssl.perfora.net/www.ficaraudio.com/sess/utn154eb5b3cdcb48e/shopdata/0050_Speakers/0020_BL/product_overview.shopscript

BL12

DUAL 1 | DUAL 2

Fs: 35.2 Hz | 39.8 Hz
Re: 0.7 Ohms/coil | 1.4 Ohms/coil
Qms: 4.68 | 4.72
Qes: .25 | .25
Qts: .24 | .24
Mms: 212g | 212g
Cms: 0.96mm/N | 0.96mm/N
Sd: 480cm^2 | 480cm^2
Vas: 31.2 l | 31.2 l
Spl: 89.1dB 1W/1m | 89.1dB 1W/1m
Bl: 16.6 N/A | 22.7 N/A
Xmax: 18mm | 18mm
Rms: 1000W * | 1500W *
Sealed box: N/A cuft | N/A cuft
Ported box: 1.5-2.5cuft | 1.5-2.5cuft
Sub OD: 12.500” | 12.500”
Cut ID: 11.125” | 11.125”
Mounting depth: 6.750” | 6.750”
Displacement: 0.18cuft | 0.18cuft

I am powering it with a Soundstream RUB1.1600 Mono Amp, 1600w RMS @ 1ohm.
Ok now what I am wondering is how should he WinISD graph look? Im not sure wha I should tune the Sub to but I would like it to hit low bu still cover a decent range. I was thinking 35hz in a 2.5 cubic ft box. But still when I look at the graph I really dont know what I am looking for or what it should like like. I hope I have provided enough info for someone to help me out. Thanks a lot guys.

[BOBinGA]

While I don't have any experience in car audio, if that were a home sub, it looks like too big of a box, tuned too low. It will give you that classic one note bass. But in this case it would give you the one note at 25hz and there is not that much down that low.

Second, in a car you will get some cabin gain which basically boosts the frequencies below 60 hz or so. This is where I don't have knowledge. You might look at some of the car audio forums and see what they recommend for simulating cabin gain.

I would suggest that you make the box smaller, tune it higher, and shoot for a smooth downward slope with no humps from about 60 hz down to 25 hz to compensate for cabin gain. You can also use the EQ/Filter tab to add in the low pass crossover you intend to use.

-Bob

[Villainstone]

TY for your advice. I have been reading, and researching, and it seems that manufacturer recommends... "Ported box we recommend using 1.8-2.5 cubic feet @ 30-37Hz (I personally think that a 32hz tuning is optimal, and has the most output and is still the most musical daily driving). Use 12-16 square inches of vent area per cubic foot of volume"
So Im just gonna follow what they recommend. I still wis I knew what to look for in these graphs lol. Thanks again buddy.

[BOBinGA]

On your link, they recommend a 0.5 to 1.5 cu.ft box. Just for fun, I put the basic parameters in WinISD and tried to come up with a reasonable box. That is a very difficult driver to work with. I cannot come up with a good box size or tuning for it. If you haven't purchased it yet, I would suggest you try something else. The problem is the very low Qts and Vas. The best I could come up with was about 0.5 cu.ft. tuned to about 25, but i don't know how you would get a 5 ft pipe in a half cu.ft. box.

-Bob

[Villainstone]

I think you were looking at the BL 10. The BL 12" is rated for a 1.8-2.5 cubic ft box. Thanks for taking out the time to model it for me. I you dont mind would you mind giving it a shot with the BL 12"? Thanks again ttyl.

[BOBinGA]

I still come up with something like a 1.0 cu.ft. box tuned to the low twenties. But this again requires a 3 ft long 3 in diameter pipe. These low q drivers really need a passive radiator and I haven't modeled those.

-Bob

[Villainstone]

hmm. Well I am looking at different subs like you have suggested. I found wo that are sem to be very workable. I can make two almost perfectly flat, with a 2.5^ft box @ 32Hz. I really do appreciate the time you have taken out to help me, Thank you. I will update in this thread or another a bit later for anyone interested lol