room tuning 12ftx12ft room

Hi G19276,

Regarding your plan to absorb the entire front wall and 4feet extending along the front section of the side walls, I would suggest avoiding this approach as it mimics the live-end dead-end (LEDE) room layout. The LEDE concept is something that came out of the 1970's from Don/Chip Davis/Syn Aud Con for recording control rooms. It's based on mostly ill-conceived ideas that stem from a misunderstanding of the Haas effect which describes the level at which a delayed reflection sounds equally loud to the direct sound. LEDE rooms sound very strange, they do not achieve what they claim, and to work well you need to add tons of absorption.

Have you measured the room’s frequency response yet? You can use simple test tones (RealTraps has a free and a great file from 10-300Hz) and a Radio Shack SPL meter to see where the problem frequencies lay. Doctors Toole and Olive’s research and philosophy with acoustical treatment is to diffuse or absorb reflections that do harm at the listening area and leave alone the ones that do potential good. Everything else can be ignored since they never arrive at the listeners' ears or if they do, they are well below the threshold of harm either in SPL or time delay or both.

The lateral reflections are beneficial - particularly in stereo - since they can produce greater apparent source width and spaciousness, while the front/rear wall reflections can decrease these attributes since they come from the same direction as the direct sound. Try putting bass traps in all 4 corners floor to ceiling and in the middle of the back wall with diffusers on either side of this centre back wall absorber. Also consider placing diffusion in the middle of the front wall (the wall behind the speakers). Side walls should be reflective or diffused at 1st reflection points unless you’re into more focused imaging in which case try absorbing the first side-wall reflections. Ceiling can be either diffused or absorbed

Your 2” thick absorbers are too thin. You will need to double or triple them up to get to 4” or 6” thickness so that they behave as a broadband absorber rather than a low-pass filter that throws your speaker’s tonal balance off. A generous air space (e.g. 6")is also best to take their effectiveness down to lower frequencies. You need to attenuate the entire spectrum of the reflection which a 2” thick absorber won’t achieve – the thicker the better. Come to think of it, you’re you considered using a diaphragmatic bass trap rather than the more popular fiberglass filled ones? The diaphragmatic ones hang on the wall and are about 4” thick so are not intrusive on limited floor space of your small sized rooms. They are however more costly. For diffusers for your small room you will need to use ones that you can sit closer to which means types of diffusers that don’t offer temporal effects or diffuse in two directions so that only about 50% of the reflections are coming back to you. Examples of these better suited diffusers for small rooms are polyfusers (hemi-cylindrical is a better descriptor), Skyline or 2dimensional QRDs. For what it’s worth my room pictures show the hemi’s and Skylines and both are very effective.

You will also likely need parametric EQ to tame the bass peaks that are heard at the listening position and/or multiple subwoofers.

Lastly, a little education on small room physics goes a long way. Pick up Dr Floyd Toole’s book and study it.

Good luck.

05-22-11: Br3098
1- 12x12 is going to be problematic no matter how much you treat. Try shortening the effective dimensions of the room by adding a bookshelf of LP racks to the back wall (behind you). If you arrange it properly, it will act as a diffuser. While it may seem counter-productive to make the room smaller, the dimensions are working against you more than the size."

Everything I read and was told when researching treating my 12' x 13' room was to never make the room smaller. A square is bad, a smaller rectangle is worse.
I've had good luck with a method (I forget - Audiophysics??) that suggests putting the speakers 1/3 into the room (4' in our case) and the listener against the back wall (treated). EQ Triangle or thereabouts. I suggest giving that a shot, it worked well for me.

I'm a small room expert. Sebrof has it right, pull the speakers out into the room to kill the booming bass, just like any room. A foot or two forward will kill the bass. Small rooms usually have problems with bass cancellation, too much bass is easier to deal with. If you are listening against the back wall you can move your chair out into the room a little more.

Let's face it - if you are into full range music (and who isn't?), small rooms are tough. And frankly, square rooms just suck unless they are very large. Based testing and experimentation in my own lilliputian space, I will take (for example) a 12x9.5 room with good dimensions over a 12x12 room any day. I was never able treat a square room well enough so that I enjoyed listening in it. But that's just me.

My second point regarding wall proximal speaker placement - to each his (or her) own. In a 12x12 room, how far apart do you intend to seperate the speakers? Let's assume a modest 7'. So unless you are going to listen in the nearfield position (always an option) you are going to be approx. 1' off the back wall; probably a little more. If your room is multi-use and you are mostly watching TV that's OK. For critical listening, maybe not.

Try a variety of suggestions and see what works best for you.

Obviously you guys are not familiar with Vandersteen speakers, their design and the amount of bass they are capable of. All of the room treatment in the world and moving speakers/listening position will not make up for the fact that his speakers are not matched for his room.