cadaver

Is infinite baffle and free-air the same thing? Meaning, they both use a LARGE space as the "box" and if so, would it be worthwhile to put a speaker in the spare tire
cover (like you see some folks doing on here) without an enclosure behind it. You know, just the speaker mounted in the spare tire/cargo cover and nothing else?

Any advice/comments welcome

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biohazardous_customz

not really. they are pretty much the same the same but the infinite baffle is basically a series of "filters" that create tension as the air trys to push through which causes the speaker to think it is in a box with air space, depending on materials used in the baffle and thickness etc. you can recreate the airspace and the subs will perform pretty well..free air is basically just mounting the su the main thing to remember here is to be sure to seal off the waves coming from the rear of the sub from the front of the sub or you will get cancellation... infinite baffle is a good choice in small space applications but is definitly not your choice if you want to get SPL but you can get pretty good sound either way you go.
Hope this helps

Justin

JLTD

Technically speaking, an infinite baffle should be infinitely large. In real life, this is not practical. In regards to car audio, infinite baffle means really large sealed enclosures (like a car door or trunk). The difficult part of infinite baffle is to make sure that the rear wave of the speaker does not come into contact with the front wave. A speaker makes sound in both the front and rear and the rear wave is 180 degrees out of phase with the front (opposite. If the two waves meet, the net result is zero (they cancel). Most midrange speakers are designed for infinite baffle applications. Infinite baffle subwoofers have never been very popular due to their limited mechanical power-handling and difficulty of implimentation (correctly).
Technically speaking a free-air speaker should work perfectly even if suspended in the middle of a room all by itself (like from a wire). I don't know of any speaker that work properly this way. If you have ever seen 6" x 9"'s sitting on the rear deck of a Monte Carlo you have seen (and heard) a free-air system.

chadfo

They are not actually the same thing but are very much related.

A free-air speaker is one designed to sound well without the use of a small enclosure. They are made to be placed in the rear deck of a car, for example, and still sound good.

An infinite baffle is just a baffle that prevents the rear waves from cancelling the front waves but doesn't have a specified enclosure size. For example, the rear deck of a car. The rear waves can't reach the front and cancel them out but there is no specific enclosure behind it.

So you can see that the free-air speaker is one that is designed to be used in an infinit baffle configuration.

To answer your question about putting the sub in the spare tire cover: no! What you'll have is a very big noise maker back there. The cover is not strong enough to withstand the movement of the sub and will likely tear apart after a while. You'd also have to remove the spare to have enough room for the sub. If you are going to do that you might as well build a custom enclosure so it will sound good.

cadaver

To answer your question about putting the sub in the spare tire cover: no! What you'll have is a very big noise maker back there. The cover is not strong enough to withstand the movement of the sub and will likely tear apart after a while. You'd also have to remove the spare to have enough room for the sub. If you are going to do that you might as well build a custom enclosure so it will sound good.[/quote]

i appreciate all the info. regards the spare cover, would it be more advisable to make a new one of MDF with the speaker mounted in it and a box attached underneath to get the good sound?

chadfo

Yes. If you want to use that space, an MDF baffle and box is the best and cheapest way to go. You could also use fiberglass but that gets much more expensive and challenging.

mandos

Free-Air=how we test our speakers.

Hook it up, nothing on it, play. With a sub, you likely won't get any sound. Many people didn't understand the difference between free air and IB when they bought our Eu-700s and were wondering why they weren't making any bass when sitting on the floor w/ speaker wires in them, it's because it completely cancels itself out.

Here's a free-air video:

http://www.edesignaudio.com/video/700video.wmv

IB=what your mids in your doors are doing....if your doors are sealed. Ideally, there'd be infinite airspace in front of and behind the speakers, it'd be like no enclosure at all, but w/o the cancellation issues of free-air. Enhances low end response but at the sacrifice of your mechanical power handling(sub becomes more efficient, moves farther on less power).

That monster 18" I put in my tC...that=IB, 10 cubic foot box simulated no box at all.

Here is a good pic of IB:



8 speakers in his trunk, trunk sealed off from the interior of the car. Those speakers need around .3 cubes a piece for normal sealed boxes, so it'd be a total of 2.5. That trunk is at least 20 cubes....so big it's like nothing at all.