# Putting speakers in an 'acoustic panel box'?



## atledreier (Mar 2, 2007)

I have my LCR speakers behind my screen, and have some room. I have 4" panels behind the speakers on the front wall, and on the 1st reflections points on the side walls. All four corners are chunked, floor to ceiling. No ceiling or floor treatment.

I thought I might try to build a 'box' for each speaker out of acoustic panels, completely covering the speakers and extending out from the edges of the front baffle toward the screen. 4" or 8" thick. This would hopefully do a better job of killing the side and floor/ceilign reflections than my current setup, and I'd also get more air between the panels and the boundaries of the room.

My speakers are Klipsch KL-650THX on 4' stands.

What are the potential pitfalls and drawbacks of this compared to the 'normal' setup with panels against the walls? Looks doesn't matter, it's behind the screen anyway.
Reason I ask and don't just try it is that it involves cutting up some of my existing panels, so if it doesn't work I need to buy and make new ones.


----------



## frd (Nov 5, 2009)

that going to work better but make the box little bigger and movable so you can control how the box going to resonance.
some speaker enclosures are designed and intended(on purpose or accidentally) to have some vibrations so with covering the enclosure you may just muffle the mid bass resonances.
in my idea if you make it something you can move and tune you can control how the panels going to interact with enclosure vibrations ...
but its beneficial
AND YOU YET NEED SAME PANELS BECAUSE BASS & MIDBASS no matter how you box your speaker spreads and make its fundamental modes in your room . and to mention it they can easily pass through the panels as well... 
lets say you more control enclosure resonance than controlling your room sound
so don't cut the panels and make a new box out of rockwool 705 

you can buy rockwool 705 and make a box


----------



## bpape (Sep 14, 2006)

Well, if what you're talking about is something made from purely OC703 or equivalent with no real hard surfaces anywhere, it shouldn't hurt anything, though not sure how much it will help. The Klipsch's are relatively controlled directivity due to the horns and the THX spec. 

You might find more improvement simply by attaching some thing (maybe 1") absorption to the front baffle of the speakers themselves to minimize any comb filtering between the screen (none are 100% AT, they all reflect something) and the front baffle of the speaker.

Bryan


----------



## atledreier (Mar 2, 2007)

Yeah, I guess....
I was indeed thinking of a OC705 equivalent (Rockwool acoustic panel) only 'box'.

I thought maybe I could get away with no panels on the side walls, and meybe dampen the floor and ceiling reflections as well. I have no other means of killing those reflections.

Also, my biggest issue is lack of midbass. I thought maybe I could lessen the SBIR impact with some heavy damping around the speakers.


----------



## lsiberian (Mar 24, 2009)

atledreier said:


> Yeah, I guess....
> I was indeed thinking of a OC705 equivalent (Rockwool acoustic panel) only 'box'.
> 
> I thought maybe I could get away with no panels on the side walls, and meybe dampen the floor and ceiling reflections as well. I have no other means of killing those reflections.
> ...


Sean Olive says treating first order reflections was actually detrimental in his perceptual research at Harman. 

I'd start with the back and front first. Then start dealing with other areas.


----------



## bpape (Sep 14, 2006)

Let's put that in perspective. Dampening first order reflections may or may not be beneficial depending on timing and assuming that the off axis response of the speakers is very very similar to the on axis response. Many, if not most speakers have completely different high frequency response curves even as little as 20 degrees off axis. Those reflections are now, not only out of time, but also of a different spectral balance than the direct sound.

In this case, with controlled directivity, the response should be relatively close.

Bryan


----------



## atledreier (Mar 2, 2007)

So, would 8" of panel around the speaker box be enough to reduce SBIR at all?
And I really don't see the harm of reducing reflections by extending the panels in front of the baffle just leaving a 'funnel' toward the screen.


----------



## bpape (Sep 14, 2006)

How much space do you have behind the speakers (front baffle to wall behind) and from the center of the box to the walls beside them?

Bryan


----------



## atledreier (Mar 2, 2007)

I have about 60cm (2') from screen to wall at the center, and a little more, about 80cm, on the sides (curved screen). There is about 4'-5' from the LR to the side wall, but some of that is taken by corner chunks.
The speakers are about 13" deep, with front firing slot port.

http://www.klipsch.com/na-en/products/kl-650-thx-specifications/

My setup without the screen fabric:


----------



## bpape (Sep 14, 2006)

OK. You will gain some SBIR control behind the speakers but you don't need 8". Beside them, SBIR isn't really much of an issue with that kind of space.

Bryan


----------



## atledreier (Mar 2, 2007)

Well, I tried it, and it really didn't do much. Some deep, narrow nulls moved a little, and some of the reflections were altered ever so slightly, but overall it was marginal at best.

I did discover a rattle in my left front though. Seems to come from where the horn meets the driver. It resonated at around 70Hz and I could dampen it by putting a little pressure on the horn with my hand. Didn't have time to check the other two speakers.... Going to investigate further. :dontknow:


----------

