RICK FITZPATRICK
New member
Hello everyone. Ok, heres a DIY random ART diffuser design. The picture shows one made of Maple, but you could use Fir 2x2 which actually is the nominal dimension. It's really 1 1/2" x 1 1/2". But there is a trick to this one which is pretty cool, and makes cutting and assembly easier.
Look at the picture. Look good. Look at the top layer. Imagine if the layer was a piece of Maple countertop that was prelamed togeather and they cut the end off which left the random lengths as shown. Say they had 12 identical pieces. What they did was take one, and made it the top layer. Then they took another one, and FLIPPED it over and moved it to the opposite edge of the backer(1/2" ply). The rest is made of alternate layers of Layer 1 and layer 2. But since you will not have countertop cutoffs, and will be assembling these from scratch, heres some clues to how to do it. If you are using hardwoods as shown, you MUST have these milled(planned) at a local cabinet shop. You could even have the 2x2 milled, and the pieces cut. As you will see, there are only 6 sizes, 5 of which have 24 pcs. per diffuser unit, and part F requires 12 pcs.
If you are cutting Fir 2x2 from your local do- it yourself lumberyard, buy KILN DRIED or if you go to HOME DEPOT, they have dried HEM FIR 2x2. But remember, these are dried after milling so each pc will be a little different nominal dimension. Not much, but when glued up the overall width may vary. Thats the point of having the 2x2 milled, as each piece will be identical. Then you only have to set up a cutoff saw,(radial arm or chop saw, and cut them. NOTE: It might be easier to add another 1/2" and cut all pcs square first, and then cut the angle which will cut them to length. Note the angle is noted at 1/2" but its around 20degrees and doesn't matter much. Also, you can increase the nominal dimension to 4x4(actually 3 1/2" x 3 1/2" but the backer will have to be increased incrementally also to match.
That would be 12 x 3 1/2" in both dirrections. Or what ever nominal dimension you wanted to use. The ones shown are 1 1/2" square
http://home.rcsis.com/beachchic/ArtDiffuser2.jpg
http://home.rcsis.com/beachchic/ArtDiffuser5.jpg
http://home.rcsis.com/beachchic/DIFFPRTSABC.jpg
http://home.rcsis.com/beachchic/DIFFPRTSDEF.jpg
http://home.rcsis.com/beachchic/DIFFPRTSPLY.jpg
Ok, now to the details. You will see the assembly sequence in the drawings but heres how it goes.
http://home.rcsis.com/beachchic/DIFFGRPS.jpg http://home.rcsis.com/beachchic/DIFFLYR1.jpg
First, if it were me, I would allow 1/2" extra on the length of each pc. That way, after you have each Layer(12 assemblies) you can recut the rear edge on a cutoff which will make for a much nicer edge for assembly.
Ok, now, at the beginning, I would set up a jig on a pc of 3/4" partical board about 24" x 24" square. Cut a pc of 2x2 24"long and a pc 22 1/2" long. Pre drill 2 screw holes in each pc. Mount the 24" pc along one edge with screws. Then, using a framing square, lay the square up against the mounted 2x2 to acurately square the other 2x2
at exactly 90 degrees. One thing about wood. Don't trust the accuracy of the squareness of panel material. Its NEVER perfect. A framing square is the only way to guarantee assembly that is SQUARE. Now, place the other 2x2 up against the opposite flange of the square and aligned to the edge of the panel. See what I mean. IF the panel is actually square, they will be flush. If not, the edge will taper one direction or the other. Now, holding the second 2x2 against the square's tongue, fasten it down with screws. Now the panel should look like a square panel with the 2x2s along 2 perpendicular edges, and looks like the SQUARE. What this gives you is a jig that allows the GROUPS to be glued and clamped squarely prior to assembling the groups into Layers.
Ok, now look at the GROUPS layout. There are GROUP 1 and GROUP 2. Look carefully. Pieces E,D,C, of GROUP 1 are a mirror image of GROUP 1. Pcs A & B are oriented the same as GROUP 1. Alright, this is what I would do.
I would glue and clamp(use the jig to clamp to with a piece of paper under the diffuser pcs, between them and the jig. This keeps the pcs from gluing to the jig. You can belt or vibration sand the paper off later.)
Layout one set of GROUP 1 pcs to match the drawings. Set this aside for a visual reference as you are assembling. Now, Note where they touch, and maybe mark with a pencil where they do not. It will give you a location where to place the glue. Use yellow carpenters glue. Keep a bowl of water and a rag handy to wipe the glue off the top face of the assembly after clamping. Now, run a bead of glue in the locations where they touch on one pc at a time and place it in the jig. You will have pcs A,B,C,D,E & PART F on group 1 only. Group 2 will glue to part F of Group 1 later. Ok, this takes time but all ART does! Ha! Ok, you need to glue up 12 Group 1's and 12 Group 2's, and then assemble into 12 Layer 1s later. I know this takes time. Do one every 2 hours minimum. Or one a day or whatever time you have.
Now, when it comes time to glue up the groups into layers, use the same jig and paper. The point is to pull the joints up tight and flush to the jig. Use a mallet to pound them down to the jig after the clamps are in place. You will have 12 Layer 1's when finished. Now take each one and sand the faces flush.
http://home.rcsis.com/beachchic/DIFFLYRflp.jpg
http://home.rcsis.com/beachchic/DIFFPLAN.jpg
http://home.rcsis.com/beachchic/DIFFLYR12.jpg
http://home.rcsis.com/beachchic/DIFFELEV.jpg
As you can see in the drawings this is made up of alternate Layer 1, and Layer 2. Layer 2 is SIMPLY a Layer 1 FLIPPED over and moved to the opposite edge. Now, as I said before I would have made the pieces (A through F) 1/2" longer. Once a layer is assembled and sanded I would cut off that 1/2" on a radial arm which will give you a nice square and perpendicular rear edge for mounting to the backer. On EACH ROW of the backer I would predrill 2 to 4 screwholes and countersink on the rear face of the backer. This gives you a way to pull up each layer tight to the backer.
Start with the top layer. Now, once its glued and screwed in place, that gives you a face to clamp the next layer to. In fact, if it were me, I would also predrill screwholes on each succesive layer with countersinks on the bottom face. This gives you 2 perpendicular places to screw each layer to the preceeding layer.(Glue too!)
Well, its a lot of work, but when you get done their pretty cool as you can see.
How many of these units you want to make depends on you. I saw a studio with only one of these at the center of each wall(medium sized booth) Well guys, thats about it. Hope it goes well if you decide to build these. They are EXPENSIVE to buy. But if it were me, I'd build 8 of these at a time. And probably set up for multiple jigs.
http://home.rcsis.com/beachchic/DIFFMULTI.jpg
One other thing. I am not an acoustician, and do NOT guaruntee these actually work as designed. But I do know if bookcases and books work to some degree these will to cause sound reflects off everything solid. This will allow the sound to reflect at different times. Or so the theory goes. I've read lately, where some people are really wondering if quadratics work as stated also. Sooooooo, go figure. Anyway, have fun.
fitz
Look at the picture. Look good. Look at the top layer. Imagine if the layer was a piece of Maple countertop that was prelamed togeather and they cut the end off which left the random lengths as shown. Say they had 12 identical pieces. What they did was take one, and made it the top layer. Then they took another one, and FLIPPED it over and moved it to the opposite edge of the backer(1/2" ply). The rest is made of alternate layers of Layer 1 and layer 2. But since you will not have countertop cutoffs, and will be assembling these from scratch, heres some clues to how to do it. If you are using hardwoods as shown, you MUST have these milled(planned) at a local cabinet shop. You could even have the 2x2 milled, and the pieces cut. As you will see, there are only 6 sizes, 5 of which have 24 pcs. per diffuser unit, and part F requires 12 pcs.
If you are cutting Fir 2x2 from your local do- it yourself lumberyard, buy KILN DRIED or if you go to HOME DEPOT, they have dried HEM FIR 2x2. But remember, these are dried after milling so each pc will be a little different nominal dimension. Not much, but when glued up the overall width may vary. Thats the point of having the 2x2 milled, as each piece will be identical. Then you only have to set up a cutoff saw,(radial arm or chop saw, and cut them. NOTE: It might be easier to add another 1/2" and cut all pcs square first, and then cut the angle which will cut them to length. Note the angle is noted at 1/2" but its around 20degrees and doesn't matter much. Also, you can increase the nominal dimension to 4x4(actually 3 1/2" x 3 1/2" but the backer will have to be increased incrementally also to match.
That would be 12 x 3 1/2" in both dirrections. Or what ever nominal dimension you wanted to use. The ones shown are 1 1/2" square
http://home.rcsis.com/beachchic/ArtDiffuser2.jpg
http://home.rcsis.com/beachchic/ArtDiffuser5.jpg
http://home.rcsis.com/beachchic/DIFFPRTSABC.jpg
http://home.rcsis.com/beachchic/DIFFPRTSDEF.jpg
http://home.rcsis.com/beachchic/DIFFPRTSPLY.jpg
Ok, now to the details. You will see the assembly sequence in the drawings but heres how it goes.
http://home.rcsis.com/beachchic/DIFFGRPS.jpg http://home.rcsis.com/beachchic/DIFFLYR1.jpg
First, if it were me, I would allow 1/2" extra on the length of each pc. That way, after you have each Layer(12 assemblies) you can recut the rear edge on a cutoff which will make for a much nicer edge for assembly.
Ok, now, at the beginning, I would set up a jig on a pc of 3/4" partical board about 24" x 24" square. Cut a pc of 2x2 24"long and a pc 22 1/2" long. Pre drill 2 screw holes in each pc. Mount the 24" pc along one edge with screws. Then, using a framing square, lay the square up against the mounted 2x2 to acurately square the other 2x2
at exactly 90 degrees. One thing about wood. Don't trust the accuracy of the squareness of panel material. Its NEVER perfect. A framing square is the only way to guarantee assembly that is SQUARE. Now, place the other 2x2 up against the opposite flange of the square and aligned to the edge of the panel. See what I mean. IF the panel is actually square, they will be flush. If not, the edge will taper one direction or the other. Now, holding the second 2x2 against the square's tongue, fasten it down with screws. Now the panel should look like a square panel with the 2x2s along 2 perpendicular edges, and looks like the SQUARE. What this gives you is a jig that allows the GROUPS to be glued and clamped squarely prior to assembling the groups into Layers.
Ok, now look at the GROUPS layout. There are GROUP 1 and GROUP 2. Look carefully. Pieces E,D,C, of GROUP 1 are a mirror image of GROUP 1. Pcs A & B are oriented the same as GROUP 1. Alright, this is what I would do.
I would glue and clamp(use the jig to clamp to with a piece of paper under the diffuser pcs, between them and the jig. This keeps the pcs from gluing to the jig. You can belt or vibration sand the paper off later.)
Layout one set of GROUP 1 pcs to match the drawings. Set this aside for a visual reference as you are assembling. Now, Note where they touch, and maybe mark with a pencil where they do not. It will give you a location where to place the glue. Use yellow carpenters glue. Keep a bowl of water and a rag handy to wipe the glue off the top face of the assembly after clamping. Now, run a bead of glue in the locations where they touch on one pc at a time and place it in the jig. You will have pcs A,B,C,D,E & PART F on group 1 only. Group 2 will glue to part F of Group 1 later. Ok, this takes time but all ART does! Ha! Ok, you need to glue up 12 Group 1's and 12 Group 2's, and then assemble into 12 Layer 1s later. I know this takes time. Do one every 2 hours minimum. Or one a day or whatever time you have.
Now, when it comes time to glue up the groups into layers, use the same jig and paper. The point is to pull the joints up tight and flush to the jig. Use a mallet to pound them down to the jig after the clamps are in place. You will have 12 Layer 1's when finished. Now take each one and sand the faces flush.
http://home.rcsis.com/beachchic/DIFFLYRflp.jpg
http://home.rcsis.com/beachchic/DIFFPLAN.jpg
http://home.rcsis.com/beachchic/DIFFLYR12.jpg
http://home.rcsis.com/beachchic/DIFFELEV.jpg
As you can see in the drawings this is made up of alternate Layer 1, and Layer 2. Layer 2 is SIMPLY a Layer 1 FLIPPED over and moved to the opposite edge. Now, as I said before I would have made the pieces (A through F) 1/2" longer. Once a layer is assembled and sanded I would cut off that 1/2" on a radial arm which will give you a nice square and perpendicular rear edge for mounting to the backer. On EACH ROW of the backer I would predrill 2 to 4 screwholes and countersink on the rear face of the backer. This gives you a way to pull up each layer tight to the backer.
Start with the top layer. Now, once its glued and screwed in place, that gives you a face to clamp the next layer to. In fact, if it were me, I would also predrill screwholes on each succesive layer with countersinks on the bottom face. This gives you 2 perpendicular places to screw each layer to the preceeding layer.(Glue too!)
Well, its a lot of work, but when you get done their pretty cool as you can see.
How many of these units you want to make depends on you. I saw a studio with only one of these at the center of each wall(medium sized booth) Well guys, thats about it. Hope it goes well if you decide to build these. They are EXPENSIVE to buy. But if it were me, I'd build 8 of these at a time. And probably set up for multiple jigs.
http://home.rcsis.com/beachchic/DIFFMULTI.jpg
One other thing. I am not an acoustician, and do NOT guaruntee these actually work as designed. But I do know if bookcases and books work to some degree these will to cause sound reflects off everything solid. This will allow the sound to reflect at different times. Or so the theory goes. I've read lately, where some people are really wondering if quadratics work as stated also. Sooooooo, go figure. Anyway, have fun.
fitz
Last edited:
So, who do you believe? Proof to me is my ears. Not words. And since I've never heard one, well......I don't know shit. I like RPG because it was based on a firm scientific foundation. But untill I hear it, that don't mean shit to me. And like you say John, your preference in the control room is, well I won't quote you....... but it tells me something too. Your opinions are highly regarded by me. And lots of other people who also respect you refer to you all the time on other places on the net. So who am I John? Just a dickhead with nothing to offer but pics and links and a few words of unqualified opinion. Thats why I try and say nothing anymore. I hope that explains my statement.
And really, other things have made me realize something. Like this. How the hell can a RFZ co-exist with a diffuser
Sounds like an oxymoron to me.