Sound Diffusor

[Ho Nguyen]

I'm looking at doing some sound diffusion behind my ESL-X. I found these fake grass panel on Amazon that looking interesting.

Amazon Link

Anyone have any experience using these in a audio room?

I've tried absorption panels and it takes away too much of the life of the speakers. So I'm thinking diffusion may be better here.

 

[JonFo]

It will scatter the sound randomly, which means some will hit the ceiling, some the side walls, some towards the center of the room and some back at the panel. In general, comb filtering is the result.

If looking for true 2D diffusion, then look at commercial diffusers designed for audio. A 2D diffuser will only spread it horizontally, which might get you the results you seek.

I only use diffusion, as part of an Abfuser, for my rear channels, as in that application, some widening of the sound field is helpful (but less so for Atrmos). The front wall is nearly entirely covered in absorption, which yields a very focused and accurate soundstage for multichannel and immersive music.

 

[Mirolab]

Hmm... interesting idea. It's more like Clover than grass. It will scatter high frequencies somewhat, and would be only slightly better than a bare wall. I don't think it will do much at mid frequencies. A 1kHz (or lower) wave will still just bounce off the grassy wall and keep moving as if the fake grass wasn't even there. I do use absorption behind my M-L panels, but I do agree that diffusers would be the better option for a livelier sound.

 

[Leporello]

I'm looking at doing some sound diffusion behind my ESL-X. I found these fake grass panel on Amazon that looking interesting.

Amazon Link

Anyone have any experience using these in a audio room?

I've tried absorption panels and it takes away too much of the life of the speakers. So I'm thinking diffusion may be better here.

They look like they might supply some random diffusion, and some absorption. You'd have to try them out, barring a response from someone who has.

But they're kind of pricey to buy and try out, in the event they don't satisfy. You'd be better off putting the money toward real quadratic residue diffusers such as RPG sells. Or if you're handy with woodworking, you could make your own. Also, if you're handy with discrete Fourier transforms, you can convince yourself QRD are optimal for random scattering and avoiding comb filtering.

Horizontal only diffusion is optimal for virtual line sources like ESL's. But I wouldn't worry too much about comb filtering from floor and ceiling reflections if the scattering is truly pretty random.

So my advice is, if you can borrow or return the fake turf things (or find another use for them if they don't work out) go ahead and try them out, otherwise save up for a commercial diffuser product (and if you buy those from an audio dealer you can almost certainly return them if they don't work out).

 

[Leporello]

In general, comb filtering is the result.

Not if the scattering is random.

 

[audioxcel]

I'm looking at doing some sound diffusion behind my ESL-X. I found these fake grass panel on Amazon that looking interesting.

Amazon Link

Anyone have any experience using these in a audio room?

I've tried absorption panels and it takes away too much of the life of the speakers. So I'm thinking diffusion may be better here.

My guess is that those would be more absorbers than diffusers. The best results I have ever achieved on he cheap were with adjustable window blinds. They seemed to reduce reflections to increase focus of the soundstage without absorbing too much life out of the sound.

 

[Brad225]

These DIY panels don't have a lot of WAF but have worked very well in my room.
1/4" foam board and glue the bottoms to plastic martini glasses.
Spray paint them your choice of color and hang them any way you choose. Mine hang from the top of the absorption panels so I can move them side to side anywhere I want.
I would guess you could have them stand on the floor on legs of some kind and be moveable.

 

[Mirolab]

My guess is that those would be more absorbers than diffusers.

There's nothing about that plastic grass that will absorb sound. It will just scatter and interfere with high frequencies. Absorber material needs to be soft, mushy, foamy, or fibrous to "trap" sound waves. Waves go in, but they don't some out, because the motion of air molecules get converted to heat by friction. The plastic grass does not do that.
A quick easy test is to face the material and make a loud "SShhhh" or "Ch, Ch, Ch" sound, and listen what sound bounces back at you. I've made some nice looking absorbers using 703 fiberglass or Roxul mineral wool and covering with solid or printed cloth. Go to a fabric store and you may get some great ideas for decorative panels. They don't have to look like studio foam.

 

[kach22i]

The many articles I've read combined with personal experimentation tells me a flat monolithic wall behind the speakers works best, and maybe add modest absorption and or diffusion in the middle.

However, a wall of green would look awesome, might want to spray some fire retardant on it like used on haunted houses.

Treat your first reflection point with diffusion. Lately I've been favoring the curved ones, and placed closer on the side wall towards the speaker than one would think to do using mirrors to spot them. Reason is you want the sound wave to hit the retreating arc, not the middle.