ever fully enclose S14 front speakers with fiberglass?

[cdlong]

just curious, i'll be getting some components for the S14 soon so idecided to pull the door panel off to take a look. the front speakers have a plastic surround that is open on the bottom. i'm thinking of sealing it up with fiberglass to improve the sound. anyone ever do it? any similar systems? any comments or advice would be appreciated. here's a pic for reference.

[PoorManQ45]

That is there only to protect the speaker from water.

Most speakers require a bit more air space then what you'll end upp with if you 'glass the other sid ein.

You could try an aperiodic mat enclosure. You would close off most of the bottom of it, but leave a square about ~3in in the back of it. THen you'd cut to fit an aperiodic mat.

[cdlong]

that sounds pretty interesting, do you have any more info on it? i can't find anything good.

how much airspace does a 6.5" need anyway, nobody lists specs.

[PoorManQ45]

Quote »A-periodic membranes are not a new concept. Though new to the mobile audio industry, they have actually been around for decades. Dynaco was the first known company to introduce an enclosure of this sort. Dynaco used a damping material in the vent which differs from the applications used today in the automobile environment.

Subwoofer systems have more "pros" than "cons". The greatest benefit of utilizing one of these membranes is the drastic reduction of enclosure size. The enclosure volume should be as small as possible. Generally, .3 ft^3 or so for a 10", .6 ft^3 for a 12" and .9 ft^3 for a 15", or smaller.

The a-periodic membrane is simply a resistive element consisting of a damping material such as spun fiberglass or duct board. The job of the membrane is to control the excursion of the driver. Since the a-p mat is not a solid material, it can "breathe" from the other side of the mat, I.e. the trunk. This allows plenty of air "access" for low bass extension. Overall, this will exhibit a flat impedance which makes response very predictable, unlike some traditional enclosures. Achieving the right response comes through tuning the enclosure via the mat, which we’ll get to in a minute. "Quick" attack, lower cone radiated distortion and smoother frequency response are a few other benefits. The transient and phase response have similar characteristics to an acoustic suspension enclosure (sealed). In essence, you have a very large enclosure, the trunk, with a resistive element that controls and damps the energy transfer.

With all of these benefits, there had to be a sacrifice. Efficiency is slightly lower than an acoustic suspension enclosure. However, most will agree that this does not outweigh the advantages that the a-p mats have to offer. The typical user of this system will be a sound quality competitor, not an SPL competitor, so this is not an unbearable loss, especially since you get the sound quality benefits of a large box with the power handling and damping control of a small box.

There are a few different applications possible. The most commonly seen is the "fire through seat" method found in sedans. Bass enters the listening area via the seat and uses the trunk as the "large enclosure". Another place for the driver is in the rear deck. When installing the driver in this location, the enclosure can be bypassed altogether by bolting an a-p mat to the front of the driver. What can you do if you own a hatchback? Easy! Use the world’s atmosphere as the rear enclosure by venting outside of the vehicle with or without an enclosure. Should you opt for the hatchback idea, be sure to put a Gortex cover over the a-p mat for protection from road elements and weather.

A-periodic membranes are still a bit new to the car audio industry and seldom understood. I believe that this "rediscovered" method of subwoofer loading will become more popular in the future.[/quote]Rex gave a link to a site that described the building of the enclosure. I"ll try to find it

[SickImports]

Hey guy,

The more space the speaker has the better the sound!! lived in a three story apartment about 2 years ago and built this huge *** box. about the size of half a car put a 12 inch woofer in it hit it with about 500 watts and it was shacking the whole third floor from the first floor. The bigger the better when it comes to sound. air space that is.

-chris-

[cdlong]

yeah, but sealed or vented usually sound better than free air which is what that are now.

any more info on the A-periodic membrane?

[Rex]

yeah, but sealed or vented usually sound better than free air which is what that are now.

any more info on the A-periodic membrane?

Sorry, I thought PMQ had already posted this link

http://www.usdaudio.com/products/

And Bigger is not always better, tuned/matched is better.

[PoorManQ45]

In sealed enclosures bigger is better for hitting lower frequencies. This is why Infinite Baffles are home audio enthusiast's ultimate goal. With an IB the lowest possible frequency is ONLY determined by the driver that is used. A common 10in, lets say sony, in an IB will play to around 30Hz. Whereas an Adire Audio 15 in IB will play down to ~15Hz.

Note that the lowest frequenccy I'm giving is the lowest they'll play with useable power output. Meaning you can actually feel it, not just the woofer moving back and forth.

Now ported is similar, but if you go too large the enclosure acts as an IB, but it has a port. This port screws up the IB system because the front and rear radiation are NEVER supposed to interact.

Now, most people think that if you go with a sealed enclosure it will take up less space. This is true if you don't want to hit real low frequencies.

Now, with a ported and sealed enclosure both tuned to the same frequency, lets say 25Hz, the sealed enclosure would have to be BIGGER then the ported enclosure.

[Rex]

So, a 100 cubic foot box is even better? That is bigger.

[PoorManQ45]

That would be in Infinite baffle territory.

If the driver's suspension is designed for it, then yes it would be better.

Now, like I said, in an IB "enclosure", or rather lack thereof, the only limiting factor is the driver itself

[Rex]

... If the driver's suspension is designed for it, then yes it would be better...

Now see you're agreeing with me

"tuned/matched is better."

[Silvia2b]

Yes! tuned and matched is better. The number 1 reason to build an enclosure is to suppress the rear waves off the cone and reduce cancellation while providing acoustic suspension of the woofer. Most Car audio woofers are designed to work in a acoustic suspension type of box. I would not seal the back of the factory speaker bracket. Are those alpine coax speakers in the pic? Even with the components I put in mine I didn't seal them with small enclosures. I made sure the front and back were isolated, with foam tape, 3m window sealer and lots of Dynamat.

[EW]

If you enclose the IB speakers in a small enclosure (like sealing up the pod), you will lose all midbass from the driver. An IB speaker uses the door or trunk as the enclosure. You may want to try Dynamat Dynazorb behind the door speaker to prevent rear soundwaves from bouncing off the door and back into your mid. Also, covering the door and door panel in Dynamat Xtreme will also improve the sound.

[audtatious]

A lot of manufacturers state that you should not use their mids in enclosures as they were designed for IB use. That being said, my old MB Quart 6.5" mids were in a sealed door enclosure for years and sounded great. I had contacted MB Quart support for the specs and they suggested .17cf for those particular mids... On the other hand, my current JL Audio XR650-CSi's specifically state that they should not be utilized in an enclosure.

[PoorManQ45]

The aperiodic mat enclosure I was suggesting IS a form of IB setup.

[audtatious]

Yes, but its intention is to fool the speaker into thinking it is in an enclosure, thus saving box space. No reason to attempt a apmat installation when utilizing "regular" components. Now, if you were installing dedicated mid-bass drivers in the door, then a apmat configuration may make sense.

[PoorManQ45]

yeah, true.

I suggest that you just play with it, not that you perves, and listen to hear which way you like better.