DIY Acoustic Diffusers

I use a DIY hot wire foam cutter with a beefy variable voltage dc power supply. Just Google "building a hot wire foam cutter," you'll get a load of sites telling you how to do it.

You could hunt around the [ decware.com ] site they have a kit for diffusors not to much money. Marc

How about this site for reference:

http://www.mhsoft.nl/diffusor.asp#calcul

Also, the Auralex metrofusers aren't hugely expensive, but they need to be covered somehow since they are made of Styrofoam and are butt ugly on their own. They are not based on the formula above though. They have varied widths as well as depths.

http://www.auralex.com/sound_diffusor_metrofusor/sound_diffusor_metrofusor.asp

Lastly, simply PVC tubes might be an option, but there is no real data to support them. Perhaps look up "room lenses" and you'll find something. The room lenses could also be seen as helmholtz resonators too...but I am no acoustician - that I am certain about!

Albert, doesn't foam act as an absorber? I would think you'd need something harder and more reflective like ABS plastic or wood. Where do you find a hot wire cutter?

Foam is softer than wood, but with several coats of paint the surface of my diffusers are quite solid and very effective. Remember, RPG has now opted to offer their diffusers in foam as well.

Although mine were created 17 years ago, the idea remains the same.

Is there a plan you used to determine the configuration of your diffusers? Also you indicated they were foam, what size foam pieces did you start with?

I did not do this, I bought from a DIY guy.

My foam diffusers appear to have been copied from the original RPG Acoustics QRD® 734 model. I don't know how he did it, only that they work extremely well, they're lightweight and inexpensive.

I'll bet there are places that cut foam packing and such that have a hot wire machine.

I made my own diffusors using balsa wood. The formula is available online. I bought 2"x2" balsa wood planks online (make sure to specify that they are perfectly square or they may come trapazoidal in cross section). I stained the planks, cut 3 different lengths with a chop saw (over 100 cuts for 30 square feet), sanded and stained the cut ends, and then hot glued them to a set of backer boards. They came out looking beautiful, like a modern art piece (sorry, my system post is not up to date, but if you email me I'll shoot you a photo). It took a long time to make though. Figure 4 hours to stain all the pieces, a day with two people cutting and sanding the pieces, and 2 man-days to do the gluing - if you are covering as much area as me (2 3x5 panels). They work great. If I need more, I may try Albert's system though.