Free Air Subs

[malandrin4o8 10+ year member]

Im looking to put 4 10” or 4 8” subs in my rear deck panel of my Lincoln town car. I don’t have room in my trunk do to my hydraulic system. What are some good subs that would work in a free air/IB configuration. Or what specs would I need to look for on a subwoofer to determine if they are free air compatible?
Thanks in advance.

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[Doxquzme Premium Member]

So generally speak-ering, You want the driver to be as close to .707 qts as possible and if memory serves me, you really want to be close to. .5- .6 to account for the coupling of the woofer to the cabin. Good xmax too, need to be able to move the air.

If you have the cash for four of them, I'd look here first.

IB10AU - Automotive Infinite Baffle Woofer - SQ Subwoofer

The IB10AU - Automotive Infinite Baffle Woofer for SQ and SQL. Featuring the Full Copper Faraday Sleeve, FCFS, for low distortion - Acoustic Elegance

aespeakers.com

If they're a little too rich for your taste (or like me, my back pocket) then take a look at their specs, try to find something close.

 

[1aespinoza 10+ year member]

If you have the cash for four of them, I'd look here first.

Whoa, those are pricey. I remember my BIL had some 12" JBL subs in the Avalanche midgate. They sounded decent but I did not read the model number on them. So at least we know those JBL subs work IB and are budget friendly.

 

[Doxquzme Premium Member]

Whoa, those are pricey. I remember my BIL had some 12" JBL subs in the Avalanche midgate. They sounded decent but I did not read the model number on them. So at least we know those JBL subs work IB and are budget friendly.

Yep, the JBL W15GTI (Mk II) or the original one? Seems like that had a QTS of around .5 and like 40mm total xmax, something like that.

 

[Buck 5,000+ posts]

You might try looking up aftermarket oem sub replacement or something. There's 8's like that, like when blaupunkt had a sale on 8's a long time ago, those 8's were more designed to be as cheap as possible just to replace factory speakers and be entry level. They weren't advertised as IB subs specifically iirc, but they could take full power free air. So I designed a t line for 8 $13 blaupunkts and it did a 145 something db on an audiopipe 1500 at like 36 hz. So that's one way is look for companies that replace oem rear deck subs, if you want 4 woofers that aren't super expensive. If you could fit a 12 I would recommend maybe one of Fi's IB3's. More cone area is gonna be louder here.

If you find a woofer that takes a lot of power free air you can use that, kinda regardless IMO. That's the issue with IB is mechanical control (excursion) under high power, so that's what to look for, primarily. You can narrow it down from there.

 

[1aespinoza 10+ year member]

Yep, the JBL W15GTI (Mk II) or the original one? Seems like that had a QTS of around .5 and like 40mm total xmax, something like that.

What I do remember is the dustcap logo with the JBL letters and the exclamation atop the J that made it look like a U. They literally looked like $70 subs. Not bashing.

 

[1aespinoza 10+ year member]

what specs would I need to look for on a subwoofer to determine if they are free air compatible?

What I have read is a low Fs and a QTS of 0.4 and above.

 

[Doxquzme Premium Member]

Found it!

https://support.jbl.com/on/demandware.static/-/Sites-masterCatalog_Harman/default/dwe79b3975/pdfs/W15GTI,W15GTI%20II%5EJBL%5Ees%5Esound%20quality%5E%5E%5E.pdf

 

[1aespinoza 10+ year member]

Found it!

An Fs of 25.2 Hz and QTS 0.48. That is good for IB. Although the excursion is on the low side, I do not think it affects it negatively being that it is a 15 inch sub.

 

[malandrin4o8 10+ year member]

So generally speak-ering, You want the driver to be as close to .707 qts as possible and if memory serves me, you really want to be close to. .5- .6 to account for the coupling of the woofer to the cabin. Good xmax too, need to be able to move the air.

If you have the cash for four of them, I'd look here first.

IB10AU - Automotive Infinite Baffle Woofer - SQ Subwoofer

The IB10AU - Automotive Infinite Baffle Woofer for SQ and SQL. Featuring the Full Copper Faraday Sleeve, FCFS, for low distortion - Acoustic Elegance

aespeakers.com

If they're a little too rich for your taste (or like me, my back pocket) then take a look at their specs, try to find something close.

Sheesh a little too steep for my pockets… especially when needing 4. Is the qts and xmax the only real important ones or is their more to it?

 

[malandrin4o8 10+ year member]

You might try looking up aftermarket oem sub replacement or something. There's 8's like that, like when blaupunkt had a sale on 8's a long time ago, those 8's were more designed to be as cheap as possible just to replace factory speakers and be entry level. They weren't advertised as IB subs specifically iirc, but they could take full power free air. So I designed a t line for 8 $13 blaupunkts and it did a 145 something db on an audiopipe 1500 at like 36 hz. So that's one way is look for companies that replace oem rear deck subs, if you want 4 woofers that aren't super expensive. If you could fit a 12 I would recommend maybe one of Fi's IB3's. More cone area is gonna be louder here.

If you find a woofer that takes a lot of power free air you can use that, kinda regardless IMO. That's the issue with IB is mechanical control (excursion) under high power, so that's what to look for, primarily. You can narrow it down from there.

I can May fit 2/3 12s but it would need to have them slanted at an angle. I will either be using my taramps md3000 or md1800 I have both collecting dust.

 

[djdilliodon!]

Im looking to put 4 10” or 4 8” subs in my rear deck panel of my Lincoln town car. I don’t have room in my trunk do to my hydraulic system. What are some good subs that would work in a free air/IB configuration. Or what specs would I need to look for on a subwoofer to determine if they are free air compatible?
Thanks in advance.

Build a wall, problem solved . Then you will have plenty of room.

 

[winkychevelle 10+ year member]

One audio, acoustic elegance, and stereo integrity all make good ib subs. But good luck getting decent output out of ib with subs smaller than 12inch.

Cone area is key with ib.

 

[Doxquzme Premium Member]

Sheesh a little too steep for my pockets… especially when needing 4. Is the qts and xmax the only real important ones or is their more to it?

There mostly for spec reference as they are regarded as very good, designed for, IB. that said, a QTS between 5-7 works best. Get the biggest that will fit, 4, 10s would be my guess unless you can fit 12's.

4 of these JL's might do the trick.

https://www.sonicelectronix.com/item-39835-JL-Audio-10W0v3-4.html#descriptionSection

 

[audiobaun 5,000+ posts]

Build a wall, problem solved . Then you will have plenty of room.

I was thinking the same myself. Remove back seat and get it in