Is there a material that is ligher than wood that can be used to make a QRD diffusor

I’m not in any rush right now, but I’ve always wanted to build some QRD diffusors. My biggest gripe would be hanging stuff on my wall that weighs 200lbs. Would it not work just as well to use something super light, like styrofoam, with just a small piece of hardwood on the end of each stick? Something like that would weigh significantly less, and I’m guessing that it would be almost as effective (I’d be happy to be shown that this is not true if I’m wrong here).

Are there any other materials out there that I might not be thinking of that can be used instead of solid wood?

I definitely want to see what some of the answers are on this. I’ve thought the exact same thing.
Carbon Fiber would be light :wink:

So you are saying to build the depth of the cell up with stryofoam , then cap cell with a piece of plywood? I see nothing wrong with this, though do not trust my super-sexy-science-skills ! I would almost argue the need for the wood cap and just go full-on styrofoam, seems just as reflective

The only problem I see with this idea is that I understood that the sides (of each cell) also come into play with the reflections. Am I mistaken?

Yes, that’s exactly what I’m saying. I wouldn’t be against full on styrofoam if it worked well enough.

I don’t know. I’m sure it has some effect. But I’m willing to sacrifice ideology for practicality.

Tossing this out there…buld in styrofoam, cap the top of with fiberglass? The whole top I mean…

I’ve never coated anything with fiberglass. What’s the physical process? Styrofoam is a little scary in that it would break really easily if someone brushed by it.

Maybe a silly question - would a broadband absorber do the same job as a QRD diffusor?

no, they serve different purposes. Absorbers deaded the room. Diffusors even out the tone of the reflections in the room.

ah, I see. I’m in the market for some absorbers - am planning to build them from layers of towels in a wooden frame - apparently they are way better than foam tiles. I’m trying to tame the high frequencies in my room and can’t seem to get anywhere with foam

man, that seems like it could get expensive in a hurry. I just filled mine with a dense blow-in insulation that I packed inside the frame. Seems to work well, but yes, definitely a different purpose

foam is a pretty lame absorber. Your best bet is to go with something like Roxul Safe n sound rather than towels. You really don’t want to ignore low frequency absorption. High frequencies are easy to absorb. Low frequencies are much harder and can really mess things up.

Safe n sound is relatively cheap, and you can pick it up from home depot or lowes. a good sized bag cost me $50

I’m already there! I made a set of bass traps from rock wool a while back - they really tamed the bass buildup in the room. As soon as I hung them up, I then realised I had some high end reflections which I couldn’t hear before I put up the bass traps. I basically need to treat the first reflection points in my room.

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I only worked with the sheet kind, and it is going to be hard to keep a nice crisp 90* angle and reach the calculated depth when the cell is close together. Really not supposed to have right angles in 'glass anyways, usually rounded or more of an obtuse angle.

Fiberglass may be out of the question, depends on how tight the cells work out to be. Though the styrofoams’ integrity will hold , with the pairing of the glass and resin.

to answer your question Boz yes Styrofoam or better yet plastic pellets melted together would be even better. when I put up my room treatment I sought out a professional that’s near me so this is what he guided me too he took my room size and figured out everything I needed. I’m sure some sort of QRD could be build on this substrate

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I’m no expert but my guess is that you need a heavy material in order to reflect long wavelengths, otherwise they’ll pass straight through until they bounce back from a dense and heavy material (concrete brick or whatever). In that case of course your diffusor will only diffuse shorter wavelengths, i.e. the higher frequencies. So the question realy is: which frequencies do you want to reflect? My guess is that Styrofoam will work fine for those higher frequencies. In that case the depth of the diffuser doesn’t need to be all that much either. Whereas if you want to diffuse the longer frequencies you not only need a heavy material , you also need a much deeper diffuser. Don’t ask me for any calculations, but I’m sure you can find them on the internet.

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