IB in a wall?

[ErinH]

Was just sitting around earlier and this crossed my mind. I'm sure someone has done this, but didn't have much luck in a search.

Wondering what kind of results one would get by going IB in the walls of a theater room. My thinking is to use 2 15" drivers and place them facing the 'audience', built directly into the wall.
Maybe take a 1" baffle, attach it to the drywall on the backside, and have a square cut out of the drywall. Then have grill cloth over that square cutout to conceal the drivers.

Seems like it would be an awesome setup.

 

[TLS Guy]

Was just sitting around earlier and this crossed my mind. I'm sure someone has done this, but didn't have much luck in a search.

Wondering what kind of results one would get by going IB in the walls of a theater room. My thinking is to use 2 15" drivers and place them facing the 'audience', built directly into the wall.
Maybe take a 1" baffle, attach it to the drywall on the backside, and have a square cut out of the drywall. Then have grill cloth over that square cutout to conceal the drivers.

Seems like it would be an awesome setup.

Well you would have to choose your drivers carefully, and the drywall space is not large enough. The speakers would have to be loaded by a pretty large room. Remember the drivers will have no loading. In a sealed and a reflex ported enclosure, there is high pressure in the back side of the cone. For most drivers not seeing this pressure at tuning will result in bottoming.

You would have to consider drivers designed for this purpose and have a much larger space on the rear side. Also sound will radiate all over your house.

Look on the Siegfried Linkwitz labs site for the best info around on unloaded drivers. It is a lot more complicated than you think, with an awful lot not understood, and no good mathematical model to date. Active equalization is often required in these systems.

http://www.linkwitzlab.com/frontiers.htm

 

[ParadigmDawg]

Warp researched to pretty heavily so check with him.

 

[Warpdrv]

For an IB type setup, you would need a good amount of space behind the drivers... like an attic or a false wall built and have the drivers firing out from there... even a closet is a bit tight on space, but i have seen it done...

There are plenty in wall type subs out there but you really need the cu ft to make an IB work....

Or If you wanted to do a sealed type scenario in a wall cavity, JL Audio is getting ready to release a new shallow mounted driver, but for the money, and the performance you get running the specs, I don't think its worth it...

But it is a cool new design... http://mobile.jlaudio.com/jlaudio_pages.php?page_id=213

 

[ErinH]

I understand what IB setups are like. Bout to put one in my car.

The 'rule of thumb' is that the airpsace behind the driver be 10x the Vas. I hadn't considered the airpsace in a home because I couldn't imagine that the area 'behind' the subwoofer would actually be sealed up completely. Thus, my rationale leads me to believe that this would be one case where you are truly infinite baffle. But, now that I think about it, I suppose that all cracks, joints, facets, etc would be sealed up. I was just thinking there's got to be a few areas where air pressure would be allowed to leak out of between the walls.

hmmm...

 

[Guiria]

Check out the link below
http://ibsubwoofers.proboards51.com/index.c.cgi?

I've looked around on the internet in the past and that site has the most useful information on IB setups. I considered an IB at one point but have sinced ruled them out for various reasons. Of course the opinions stated there are most likely biased towards IB's but you can still get a lot of info to help you decide if an IB is what you want.

Here isn't much IB talk around here.

Good luck

 

[Guiria]

The 'rule of thumb' is that the airpsace behind the driver be 10x the Vas.

I believe the 10x Vas should be a minimum. Otherwise you will most likely pressurize somewhat the inside of the space(backside of the driver space) and introduce coloration from that sound interacting with the driver; thus ruining the whole concept of IB to begin with.

See my previous post and link to IB fanatics.

 

[sparky77]

The only reason that I would go with an IB at the present time would be a matter of resonance and back reflections to the cone, theoreticall an inwall IB would work ok if the wall space was sufficiently large enough, but it would not likely be large enough to prevent the sound reflections off the outside of the wall from resonating through the cone. With all intents and purposes many IB's have been installed with a nearly open design that actually vented to the outside of the house leaving no significant airflow restriction on the outside of the woofer, the inside space actually becomes the cabinet so your actually for the most part living inside a subwoofer box. Active equalization is the only real way to make the most of it though, so a typical ported enclosure with a good anti-resononce design and enough damping to prevent backwave reflections is by far easier, and generally cheaper to implement.