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[quote="GlassWolf"]mine is sealed. I built mine into the spare tire well in my car.
the Q is ideal for a small sealed enclosure, if you look at the specs.[/quote]

In my experience the 18" Q lacked on the low end a little in 4 cubes sealed. Of course this was also 2 of them in 8 cubes net sealed UPFIRING :doh in the trunk of my old Caprice Sedan.

I'm hoping to have much better luck sealed in the wagon on the final install.

I guess I'm just remembering the W12Gti's implementation in competition and such. There are a lot of people still using them in largish enclosures and they're popular IB as well. But people have different goals, low Q enclosures are becoming rather popular again.

The enclosure recommendation on that sub is loosely based on the effect cabin gain will have on the sub's response. Really the tuning boils down to personal preference. Those are great SQ subs, though, very low distortion and a lot of linear output for the price. And their quality control is just fantastic.

SQ wise, I'd put them well above IDQs though. Low levels there won't be a ton of difference, but at higher outputs the Peerless just has far more ability.

This explains how I add cabin gain to winISD using a linkwitz transform:

[url]http://forum.sounddomain.com/forum/ultimatebb.cgi?ubb=get_topic;f=11;t=072900#000000[/url]

It looks complicated, but really is simply a matter of measuring the internal length of the passenger compartment as thats the only variable. I know its crude, but it really showed me how one can get low end extension from a sealed system that has an anechoic roll-off a good deal above 30 Hz. Here's a 12w6d2 in the "2003 Explorer"(2.9 m cabin length) with an 18 dB/octave butterworth lowpass with(yellow) and w/o(green) cabin gain:

[url]http://home.comcast.net/~guppyrig/wsb/media/322068/site1092.JPG[/url]

In reality you're not going to get that much low end, but you can see why home and car sub systems are entirely different beasts. An HT room is obviously not an anechoic chamber, but "cabin gain" starts at a much lower frequency.

Unfortunately that graph uses small signal analysis(1 watt of power). As I learned from correspondence with a JL Audio tech they use a much more complex program to predict in-car response that takes into account the amount of power being supplied. Apparently TS parameters change drastically when things begin to heat up. Loudspeakers as a rule are terribly inefficient. At least 90% of the power that is supplied to a subwoofer is dissipated as heat.

[url]http://www.the12volt.com/installbay/forum_posts.asp?TID=73962&PN=1[/url]

I wish I had better loudspeaker modelling software and the tools(RTA) to construct a transfer function for my truck. I'd be in tweakazoid nirvana.

:)

As it is I think I'll just go for personal recommendations from those with experience, buy a sub, build an enclosure, and hope for the best.

If you have numbers for your cabin gain, I think you can stick that in WinISD somehow and see what you'd really get. Also check out the DIYMA 12" if you're ok with a 12. It's a small box (sealed or ported), high excursion type sub. The guy who designed it actually designed it similar to the XLS (or XLSS) because he loved them so much. [url]http://www.diymobileaudio.com[/url]

I got a reply from A JBL rep who provided the TS parameters and enclosure recommendations for the W12GTi. I don't know why I didn't ask for specs on the 10 as well. The 12 only requires 1 ft^3 sealed. I assume the 10 would be much less. Both have fairly huge mounting depths so a pair would be necessary in order to have a symmetrical looking rear firing enclosure design. I was thinking about loading them facing each other in the middle, maybe at a slight angle, but I'm a bit worried what that would do for SQ.

Did some googling on the 10" XXLS autsounds and it seems these are highly lauded SQ subs. The transient response curve looks pretty weird in winISD using Madisound's recommended enclosure(1.2 ft^3 @ 38 Hz w/ 20% polyfill). Its got an extra "hump" in the upper bass freqeuncies. It does disappear when a low pass filter is added. Its just that all of the JL subs I've modeled have very "pretty" alignments. The XXLS also has a really steep roll off before 30 Hz, even steeper than the 10w5. But then there's the polyfill. I have NO idea how to model that with a ported enclosure in winISD.

I also read something where one guy compared his XLS10 autosound with an Arc audio sub(IDQ12) and its performance made the "numbers" lie. It played deeper than it should have, outperforming the larger sub in almost every category. I think I'm going to throw the small signal analysis out the window. Even when utilizing a linkwitz transform to model cabin gain, I do believe winISD is just too limiting.

Yep, my best sounding sub enclosure was had after simply asking a professional to design and build me a box with the best subs he had(Manville and the 10w5's), hehe. It worked once. It should work again.

Thanks for the advice Jonathan. I'll probably go ahead and order at least two 10" XXLS autosounds, utilize Madisound's recommended enclosure, and go from there. I just wish I understood the need for polyfill in a ported box. Why not just utilize a larger enclosure? Maybe Madisound simply tweaked the first box they built.

The 12" XXLS autosounds would be an option as well, but again madisound "recommends" a sealed enclosure and doesn't provide a ported design.

[url]http://www.madisound.com/cgi-bin/index.cgi?cart_id=7491160.26514&pid=2123[/url]

This doesn't make a lot of sense to me. After all these are "ported specific" subs are they not?

Guess I probably should just email Madisound and ask for an explanation. Haven't done any enclosure calculations yet anyways. My old HP 48sx got crushed and I just can't use anything with an "=" sign and parentheses(old habits die hard). I need to order another good RPN logic scientific calculator tout de suite.

:)

-Fishy

[quote="GlassWolf"]mine is sealed. I built mine into the spare tire well in my car.
the Q is ideal for a small sealed enclosure, if you look at the specs.[/quote]
Yeah the only Q he couldnt run stealthy is the 18 the specs show it running in at the very very minimum a 4 cubic foot box, there aint much stealthy about that and it needs much larger to sound good. my sounded pretty good in 6 cubic feet sealed.

Well that JBL is more for rather large sealed boxes, at least compared to most of the car audio subs today. I think around 1 cu ft. for a 10".

The Peerless auto subs were the ones I was referring to.

Those aren't the right ones. Definitely designed for home use.

These must be it:

[url]http://www.tymphany.com/datasheet/printview.php?id=46[/url]

[url]http://www.madisound.com/cgi-bin/index.cgi?cart_id=7491160.26514&pid=2037[/url]

Wow.

Are these the Peerless subs you were refering to Jonathan?

[url]http://www.madisound.com/cgi-bin/index.cgi?cart_id=7491160.26514&pid=1785[/url]

The recommended ported enclosure is really close to what I had with the 10w5's(1.75 ft^3 @ 32 Hz) and with that much airspace designing ports will be a breeze. Of course that alignment is probably intended for home use. May have to go with a little less volume and a higher tuning frequency. Gonna plug those numbers in to Win ISD and compare.

We may have a winner.

Thanks :)

-Fishy