What Do You Prefer for Back Wall? - Diffusion or Absorption?

[ruanddu]

Just curious to hear what you like better for your rear wall (or just in general)- diffusion or absorption? Have you tried both and compared? I haven't had a chance to yet so it'd be great to hear from those who have experimented.

Just an FYI: My room is 16x15ft with 7ft ceilings.

Thanks,
Josh

[PaulP]

Originally Posted by ruanddu

Just curious to hear what you like better for your rear wall (or just in general)- diffusion or absorption? Have you tried both and compared? I haven't had a chance to yet so it'd be great to hear from those who have experimented.

I just ran a search on "rear wall" and got 499 hits (entire threads).
Might I suggest you browse through those first ?

Paul P

[SAC]

Might I suggest that you better define your question in terms of what exactly your are trying to accomplish in terms of an acoustical response.

'How' one does it is not the same as 'why' one does it.

There are several options depending upon your preference and intended use that will determine the answer to your question..

[Glenn Kuras]

Originally Posted by ruanddu

Just an FYI: My room is 16x15ft with 7ft ceilings.

Thanks,
Josh

In a room that size (assuming it is a control room) I would focus thick absorption right behind where you sit. But there is no reason you could not put diffusion around any panels you have. Needless to say if you can only pick one with a room that size then stick with absorption.

[ruanddu]

Thanks everybody. Sorry to be so vague. The room will be used for some mixing. More for 2 channel listening and rehearsal.

Is it mainly more important to focus on absorption for the rear-wall due to bass trapping? I thought diffusion would be better for getting the room from drying out too much..? Maybe I am off on this assumption due to the room size? How about the side walls towards the rear of the room? Is that a good spot for the diffusion instead?

Thanks,
Josh

[DanDan]

The room seems a little small for diffusion to me. However opinions vary on this, and it may depend on exactly which diffusors we are talking about.
Take a look a the spectacular results with diffusion over at RealTraps.
Note is is not a case of one or the other. Small rooms typically require vast amounts of Bass Trapping. A side effect of this can be a quite dead space.
Many dislike this deadness,without giving it a fair result based chance IMHO.
I speak of a Mix environment here. I find dead useful. However for listening pleasure, I would recommend and even personally prefer some life/diffusion.
Diffusors can kill flutter, thus the back side walls and ceiling seem very likely spots to me.
DD

[Glenn Kuras]

I think the bottom line is you can use diffusion, but when the back wall is that close, you end up with some pretty bad nulls and peaks in the low end coming from that area. Diffusion just won't deal with those problems.

[bwo]

I prefer both at the rear wall. Bass trapping (and sometimes broadband absorption) right behind the seating position and diffusion next to these. I don't like diffusion though if the distance is short. Needs to be at least 6.5 feet, but more is better.

I dont't think there's a general rule. It depends on how rest of the room is treated and also the speakers and gear will play a role. One option is to have basstrapping on the floor and diffusors above.

[ruanddu]

I ended up using absorption on rear wall. I used 4 GIK 244 panels - 2 on the wall and 2 straddling the ceiling to wall corner. I also used 2 homemade 7x2ft bass traps with ultratouch cotton for the corners. Sounds pretty darn good but a tad bit on the dead side. I plan to use diffusors on the rear sidewalls to help this out. I figure I got most of the bass trapping taken care of where it hurts the most. I will work on getting you guys some pics.

Thanks.

[Glenn Kuras]

Glad it worked out for you. Looking forward to the layout.

[Weasel9992]

Originally Posted by bwo

I prefer both at the rear wall. Bass trapping (and sometimes broadband absorption) right behind the seating position and diffusion next to these. I don't like diffusion though if the distance is short. Needs to be at least 6.5 feet, but more is better.

I dont't think there's a general rule. It depends on how rest of the room is treated and also the speakers and gear will play a role. One option is to have basstrapping on the floor and diffusors above.

I agree, and it's pretty much exactly what Glenn's been saying. If you can mix up the absorption with some diffusion, then go for it. What you should NOT do in a room that size is all diffusion and no absorption on the back wall. That's a disaster waiting to happen.

Frank