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Wood acoustic diffusers have become a decorative item - loved the idea!
- Thread starter sarumbear
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OP
- Thread Starter
- #102
It’s an absorber
MAB
Major Contributor
And that room really looks like it could use some actual diffusers...
tuga
Major Contributor
Only at very high frequencies. I see it more as a deflector which diffuses slightly. And more importantly you can put it away when you aren't listening. I haven't bought them yet.
Th
Those diffusers made with Lego look cool.
I made a diffuser out of wood. You need to be confident in your fixings!
OP
- Thread Starter
- #107
You may see them as such but they are not.
A diffuser is made of reflective surfaces. This panel is absorbent. A couple inch thick upholstered panel is transparent to anything below voice frequencies. See the data sheet of a similar panel.
It is a very common mistake to confuse absorbers with diffusers. There are a wide range of absorbers on the market because they are used to insulate sound. Every commercial or multi-dwelling building use them. However, a diffuser is only used at auditoriums, studios and purpose build music rooms. They are a niche product.
OP
- Thread Starter
- #108
OP
- Thread Starter
- #110
Styrofoam is not a good material to build a diffuser. As I keep repeating, a diffuser is a reflector. Any type of foam is an absorber.
However, I they covered the foam surface once it’s shaped, with a thick material, maybe the result will be satisfactory.
It was a joke, but now that you mention it, what are the desired characteristics of the material to use? Styrofoam in closed cell foam, wood is not an homogeneous material either, specially softwood. In post #19 you said the important is that the material is rigid, which styrofoam is.
Is there a description, in technical terms, of the properties the material must or must not have?
You can make one with nickel wire and a DC power supply. Use springs across the nickel wire to keep it tensioned and increase the DC power across the wire till it gets hot enough to melt the styrofoam.
The RPG Skyline panels, made with expanded polystyrene, are simply painted.
In their sales leaflet, after explaining diffusion properties of the panel, RPG state:
'The solid expanded polystyrene core of the Skyline® provides useful low frequency absorption'
It's on page 2 here: http://www.rpgeurope.com/downloads/download.html?id=25
In their sales leaflet, after explaining diffusion properties of the panel, RPG state:
'The solid expanded polystyrene core of the Skyline® provides useful low frequency absorption'
It's on page 2 here: http://www.rpgeurope.com/downloads/download.html?id=25
Styrofoam seems an interesting choice to me as it can be reflective above a certain frequency and absorbing below that, isn't that true? First of all, it's pretty hard on its own, I would think it is already much more reflective at mid and high frequency than, say, foam rubber or rockwool. And it's closed cell, you don't even need to cover it.
In fact, I doubt the absorptive properties of styrofoam, not its reflective properties. Polystyrene is much more interesting still, and painting it to close the surface cells is exactly what I had in mind.
However, as stated a couple times already in this thread, intuition doesn't work in this field!
In fact, I doubt the absorptive properties of styrofoam, not its reflective properties. Polystyrene is much more interesting still, and painting it to close the surface cells is exactly what I had in mind.
However, as stated a couple times already in this thread, intuition doesn't work in this field!
I think the RPG diffusers are made of this type of foam (styrofoam, EPS). Because of the low density I am not totally sure what they do with low frequencies, but painting / coating them would certainly make them more reflective to HF.
Plain EPS is a poor absorber because of low density and closed cell structure, but not sure whether it's a good reflector either.
Plain EPS is a poor absorber because of low density and closed cell structure, but not sure whether it's a good reflector either.
OP
- Thread Starter
- #116
The requirement is for the material to be reflective within the range it is designed to operate. Most rigid materials are reflective.
OP
- Thread Starter
- #117
Foam rubber or rockwool are absorbers and have no place in a diffuser.
Polystyrene is better than Styrofoam but nevertheless it is still more of an absorber than a reflector. Both are used for insulating sound not reflecting. If a plastic material must be used Melamine is an option.
Indeed.
It's highly carcinogenic
And it won't work as a reflector if sealed in a container.I'm not advocating the use of foams or plastics, mind you, but wouldn't it be great if the same piece of treatment would absorb the bass frequencies and reflect everything else?
OP
- Thread Starter
- #119
This source says the risk is very low in resin form. You are not expected to eat itIt's highly carcinogenic
I'm not advocating the use of foams or plastics, mind you, but wouldn't it be great if the same piece of treatment would absorb the bass frequencies and reflect everything else?
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I don't know the answer to that, but that is how in my 10'x10' office is set up. I am listening nearfield and also sitting close to the wall. What I found is:
- I prefer absorption on my front wall vs. nothing at all
- I prefer nothing at all vs. absorption on my back wall (it absolutely killed the sound)
- I prefer the GIK acoustic diffusor/absorber panels on my back wall vs. nothing at all
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