# QRD Fractal Diffuser



## robbo266317 (Sep 22, 2008)

Saw these on eBay and wondered how effective they would be as they look like they are made of styrofoam.

http://www.ebay.com/itm/Skyline-QRD...714480?hash=item3609be83b0:g:3k4AAOSwOyJX5FMA


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## DqMcClain (Sep 16, 2015)

Took a good look at these... yup. Polystyrene. 

Since they're supposed to diffuse sound by reflecting it rather than absorb sound, I feel like the material used only needs to have a fairly smooth and rigid surface, and polystyrene fits that bill pretty nicely. What I would worry about is mounting them, as it often tends to crumble when lower density material is used (as these appear to be). Also, they don't look like they're coated in any way... that could have pretty serious consequences cosmetically. Painting can be done, but you have to take care to avoid coatings that have any kind of base that will break the polystyrene down. Anything water-based should be fine, but aerosols could present problems. 

The thing I'd be really concerned about is damage during shipping... but we'd finally get the answer to the age-old question: What do they back styrofoam in?


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## bpape (Sep 14, 2006)

If it's EPS, it can work down to the point where the material is not dense enough to deal with the frequency. If it's open stryrofoam, I'd stay away.


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## DqMcClain (Sep 16, 2015)

puukorva said:


> It's hard to say from the picture but the structure looks like it's not solid but expanded i.e styrofoam like. I'm actually thinking to order one piece just for kicks. If nothing else it can be used as a base for molding.


That's pretty much what I was thinking... at $40 and free shipping, it's a cheap experiment.


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## Tonto (Jun 30, 2007)

That's a Leanfractal design. 



> Tim Perry <[email protected]>
> To
> Quenten
> Sep 23 at 9:03 AM
> ...


The very one I'm getting ready to build. I'll be using a combination of plywood & lumber. The guy that designed them offers his plans to everyone for free as long as you don't sell them commercialy. Those dispersion fields look exactly like the ones posted on his website. I'll link it over to him and ask his advice on how he thinks it will preform. He doesn't recommend altering the # of panels, he claims it has to built exactly that way to produce the desired effect.

Here's the link to his website. Some excellent reading.

http://arqen.com/?awt_l=4u1Q5&awt_m=3xjwHvf_OYOvzB9&utm_source=diffusersdiy-list&utm_medium=email&utm_campaign=DiffusersDIY-followup&omhide=true


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## robbo266317 (Sep 22, 2008)

I look forward to hearing what he has to say.
On a side note, I wonder if they have any flame retardant chemicals as styrofoam isn't good if it burns.


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## DqMcClain (Sep 16, 2015)

robbo266317 said:


> I look forward to hearing what he has to say.
> On a side note, I wonder if they have any flame retardant chemicals as styrofoam isn't good if it burns.


At $40 with free shipping from Latvia, I wouldn't bet on anything fancy like UL Listings and such


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## Tonto (Jun 30, 2007)

That's what I'm thinking. I post Tim's response when he responds.


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