How would you do it?

[Aaron Hancock]

My brother does a lot of sound engineering and is building his own studio. He was talking about having me build a "flutter free diffusor" http://lonelyraven.zenfolio.com/img/v5/p349964626-3.jpg
I don't know the depth of the grooves yet. I'd like to make it out of solid wood. It would be aprox 4" wide, 1" thick and up to 96" long. I think I have an idea on how I would do it, but I'd love any input.
Aaron

[Sean Nagle]

Aaron, audio engineers would tell you that the depth, width and spacing of the channels have been computer modeled to perform in a particular way. If your brother can provide you with those dimensions that would be preferable. Also, is it going to be 4" wide or 4' wide? Does this mount to the wall with the channels horizontal or vertical? A 4'x8' unit could be heavy, you might want to use a light wood, fir or pine would be good.

[Aaron Hancock]

Sean,
I understand the dimensions of the grooves are very important, he has yet to send me plans. My understanding is that they can be mounted to the wall horizontally or vertically, with different results. The 4" dimension is pulled from a retailers site selling the diffusers, the ones I'll make might not be exactly 4". I'm not sure, but I think density is very important so I think pine or fir is out. My question was more about how exactly you would make the grooves. I was thinking about making up a jig to use on the table saw with a dado blade..

[Sean Nagle]

Oh I see, they are made in 4" sections and then ganged together when installed. I do know a little about acoustics though I'm not an acoustic engineer. The density should not make any difference for a diffuser like this. I have seen diffusers made of polystyrene that could also have been made of wood but perform the same.

A dado blade will need to be setup with the correct width, depth and offset from an edge, then a whole stack of 4" boards need to be run through. Adjust the three variables and repeat.

[John Schreiber]

On the picture, it looks like there are two layers glued together. The substrate has the deeper grooves and the shallower ones are glued on top.

Not sure what kind of wood to use, MDF might be best. Wear a mask when cutting.

[William Duffer]

I have to agree with John it looks like they a Layered. I would use a router and router table there is some pretty thin splines left. I would use a good hardwood to keep the lines crisp. If you are going with the 4" or so you wouldn't need to layer them. You are basically making a very custom molding.

[Aaron Hancock]

It doesn't look like two layers to me, but I'm sure your eyes are better. I was thinking about doing it on the table saw with a dado blade. I was going to make a series of spacers, exactly the size of the space between the grooves and ad them one by one between the work piece and the fence as I went. I was also thinking about making a sled, so I could ad spacers under the piece to vary the height.
Aaron

[Sean Nagle]

Spacers are a good idea.

[John Schreiber]

I blew up the picture and I think you are right. Those are pencil lines instead of a glue joint. There also appear to be holes, perhaps for some kind of indexing pins.

p349964626-3.jpg

[William Duffer]

Why don't you get some scrap and try it out. It's the only way to know for sure.

[Aaron Hancock]

Yeah, if I can find the time I'll knock one out this week. I might have to opportunity to make 30-50 of these, would it be a viable option to have a sawmill cut a knife and have them cut it? Any idea what I'd be looking at for a price?