Front Wall panels

[chas]

Given a room with floor to ceiling superchunks in the front corners, which option would be preferable for front wall panels?:

Three 2-inch 2' by 4' 703 panels

or

Five 1-inch 2' by 4' panels

[bpape]

We need a bit more information.

- Is this purely for home theater?
- What are the room dimensions?
- How close to the front wall are the speakers?

Bryan

[chas]

It's a family room used for television, home theater and music (pretty much in that order of importance). It's a rectangular room about 14 X 45 (about the first 16 feet of length used for the listening area). Front speakers are rear ported and about 2-3 feet from the front wall.

[bpape]

Well, it's a tradeoff. On one hand, for multichannel, you want as much of the front wall covered as possible to keep the surround field from contaminating the front image. On the other hand, the room is somewhat cubic and I'd like to have the thicker absorbtion to reach down a little lower.

Realistically if you can, the best use of what you're specifying would likely be 3 1" panels on the front wall and at least one on each side wall for reflection point control.

Bryan

[chas]

Out of curiosity, should the front wall be treated for a 2 channel listening room?

Thanks for the help Bryan.

[Ethan Winer]

chas wrote:

Three 2-inch 2' by 4' 703 panels

or

Five 1-inch 2' by 4' panels

Why does it have to be one or the other? Best is to have more absorption that is also thick enough to work to a usably low frequency!

--Ethan

[basementjack]

Your room is an instrument, and some would argue it's the most important piece in your playback chain.

So you have to be a little careful.

Just as you don't see acoustic guitars lined with insulation - you don't want to over insulate your room either.

I agree with Ethan, you should use the thickest insulation possible - my vote would be to use 4 inch, and spaced off the wall if possible.

however, I think you need to be very careful when treating your front wall. I would definately treat it as a 2 ch room first and formost. If there is any way possible, I'd do some experimenting before you commit - ie if you're thinking of doing 5 inch panels, - then by all means, get the panels and place them temporarily and then listen and make sure you haven't killed your imaging.

[chas]

Thicker panels certainly seem to be the consensus but I'm a little confused on the two channel performance - are you saying too much front wall coverage can kill the stereo imaging?

[basementjack]

Correct, Stereo "Imaging" is really an acoustics related phonomenon.
(which is why headphones sound great, but have a different acoustic feel)

So you definitely don't want to over absorb the room - and there are key locations that you'd want absorption, and others that you don't

one rule I've heard over and over, is the 5ms time window rule - the 'average' brain takes in all sounds within a 5ms window and kind of lumps them together.

ideally in your room, you want direct sound separated from reflected sound by 5ms or more.

5 ms distance wise = about 5 feet, and I'm sure you've noticed that your speakers sound better if they are about 2.5 feet off the back wall.

Sidewalls would need much more than 2.5 feet spacing, because there you're creating a triangle, one arm of the triangle is straight from the speaker to you. the other two arms are from the speaker, off the sidewall, and back to you - you want the 2 arms to be 5 feet longer than the 1st. thats almost always impossible, which is why you'll see people suggest locating those points with a mirror, and treating those with insulation panels.

beyond those first relection points, you wouldn't hear the reflected sound until it passes around the room a few times - by then easily 20,30 even 100 ms later - which adds a natural reverberace to the sound, and is what tricks the mind/ears into hearing a 'deep' and or 'wide' soundstage.

[bpape]

Unfortunately you can't just say never kill the front wall for stereo. It depends on speaker locations, what you can do on the rear wall, whether you're listening near or farfield and a host of other things.

Having some absorbtion directly behind the main speakers and a bit between them on the front wall is generally desirable. Some people prefer diffusion between the speakers.

My assumption as to the limitations of materials is budgetary.

Bryan

[chas]

Thanks Bryan, Ethan and Jack for the info. The more I dig into this the more I see there is a real science to room acoustics...and that treatments are not one size fits all.

My assumption as to the limitations of materials is budgetary.

Well I am cheap, but if 2 inch panels will be much better than one inch I'll certainly pry open my wallet for the additional material.

The five panel idea was an idea that I thought would look better in my room since the TV and speakers are a bit off center on the wall and I thought the three panels set-up would accentuate that fact where as a five panel array centered on the wall would minimize the distraction of the uncentered equipment. But I don't want to sacrifice imaging for aesthetics.

Hmmm...