Contour Enthusiasts Group Archives Forums Modifications Audio Need an 8" free air better than this.

Usually, you'd look at the Qts. value of the driver. If it is a high Qts rating.. somewhere around .5 and higher, the driver would be ideal for free air use. You can use a driver with a low Qts under .5, but the powerhandling due to mechanical limits would drop substantially. A driver with a high excursion, and a Qts of about .4 would also work effectively in a free air situation. You should just beware of not pushing your driver so hard, it would bottom out.

Ren

Hey Tony,

What about a pair of Apex Jr. 8" Super Sub's (total of $70) from www.apexjr.com? QTS = .514

At first, I thought the apex woofers would be ideal, but the xmax turned out to be around 4.5mm which isn't too good. He would be dropping his excursion capabilities by 70%.

Hmmmm... Forgot about the low Xmax on the Super Subs.

What about a pair of Dayton 8" Quatro Subs? Lots of good comments about 'em on the PE tech board over the past coupla months.

QTS = .40
Xmax = 9.5mm
RMS = 150w
Price = $49.72/each

Alright, they're not 8" speakers but will still easily fit as 6x9s.

6x9 Subwoofer - 2ohm

Xmax - 8mm
Qts - .80
RSM - 50w
Price - $4.89/each

You could probably fit up to 4 or 5 of them across the rear deck (at a total cost of only $25). They won't need a baffle either due to the included spacer. The 2ohm impedence gives you some interesting wiring options too.

"Qts - This is the total strength of the driver resonance. It is a combination of electrical Q (Qes) and mechanical Q (Qms). A speaker with high Qts will have a very stiff suspension."


As I understand it, speakers with stiffer suspensions are better suited to infinite baffle (free-air) applications as they are less prone to over-excursion.

The actual bass output is derived from the conal surface area and Xmax (excursion capabilities) of the driver. The more air the driver moves, the more bass you'll create.

This sub has a pretty high QTS of .8 which should help keep it from being overdriven. And, it's Xmax is also pretty darn long for so small a sub at 8mm (not a point-to-point measure which some manufacturers use to exaggerate specs).

BTW, I believe this driver was designed to be a free-air 6x9 sub.

I suspect 4 of them could move quite a bit of air with even a very modest amp (something that'll produce 100x2 @2ohm stereo - a dime a dozen amp). And, zero loss of trunk space!!!

Thanks for all the help guys.

I am gonna go with the Illusion Audio LM-10 (10").

This is thier free air sub. Thanks for all the help!

I post pics when it's in.

Ordered from SOLEN INC.

Those are neat subs. I tried getting one a while back but never found a place to order them. Good luck on the install. You'll probably have to make a 1.5" baffle (couple pieces of 3/4" MDF sandwiched together) for a free-air install.



I think a pair of ND-804's would sound fantastic in the front doors.... Can they handle mid-range up to 2500Hz or so? Might have to give Solen a call....

Illusion Audio subs and speakers are in stock and available at www.solen.ca FYI.