DIY Skyline Diffusors

[DeeDrive]

Here's some info I found in another post:

>>Here's some info I found on DIY skyline diffusors that I posted elsewhere a while back:

Hi everyone. Bill Bairley at bad bear studios in Florida built some "skyline" style diffusors using 1 inch cedar blocks and a proportion grid created by the BBC. I thought someone else might want to use this design so i converted the proportions for this post and made a "precut" list for those of you who want to buy or cut the 1x1's or 2x2's yourself and want to know how many of each length to cut. Here's the proportion grid:

0 3 4 1 2 3 3 1 4 2 3 3
3 0 1 4 2 1 1 3 3 2 1 1
3 1 1 3 1 3 2 2 1 0 2 2
2 2 2 2 0 4 3 2 3 2 1 1
3 3 1 1 3 1 1 3 4 3 1 3
2 3 2 1 2 0 3 2 4 2 1 0
2 3 2 1 3 1 2 2 3 1 3 4
2 0 2 4 4 0 1 2 1 4 2 2
3 4 1 0 1 3 3 1 0 2 3 3
1 3 3 1 2 4 1 2 0 1 3 1
2 1 2 3 1 3 3 2 4 2 3 4
2 4 2 3 3 1 1 2 0 3 1 0
<<

I had a few questions, if anyone knows anything about these.

1. These plans are for 1x1" boards, but it states the 2x2" boards can also be used, by just doubling all the dimensions. Well, most 2x2" boards are really 1.5x1.5" in actuality. Does this need to be taken into accout? What I mean is, should I recalculate everything for 1.5" boards?

2. What kind of wood would be good for this? I've found some cedar boards, but they cost about 4 times as much as some pine 2x2's I've found. Plus, I like the look of the pine MUCH better. There shouldn't be any problems with using pine should there?

Thanks for any help anyone has. Has anybody built these? It looks like a lot of cutting, but it might be worth the effort.

[cedarstudios]

I just finished building a "test" one to see how it worked out. I ended up using redwood 2"x2" 's(actually 1.5"x1.5"). I ended up multiplying every length by a factor of 1.5. The redwood was fairly light and I really liked the way it looked. It was a lot of cutting and sanding but the first one came out pretty good. I think i might make some improvements to it and build around 8 of them for my control room back wall. I'll try and post some pics of them when they are finished.

[tonymite]

looks inarestin ...

just wondering ... how does one determine when we need a trap and when we need a diffusor ? What frequency range does the diffusor diffuse at ?

[Farmerbrown2200]

This person didn't use wood at all:

http://www.bobgolds.com/DifuserKgveteran/home.htm

[AlanTide]

do-it-yourself diffusors? I might try these myself.

[pan60]

http://www.mhsoft.nl/DiffusorCalculator.html

[dj_who]

This person didn't use wood at all:

http://www.bobgolds.com/DifuserKgveteran/home.htm

brilliant.....why didn't i think of that !!!

But, would styrofoam work? Isnt the point of a diffuser for it to REFLECT the sound back at different diffused angles?

Of course I'm absolutely no expert so if this sounds silly let me know

[centurymantra]

I'm sort of wondering how well styrofoam would work as well. That aside, I know that Auralex and RPG make diffusion products out of materials that are similar if not directly related to styrofoam. I'm sure that every material works differently to some degree and would imagine that even different kinds of wood will 'sound' different. I do think styrofoam should work pretty well though. Maybe someone who knows more than me will chime in here.

Making these out of wood is a lot of work and they are quite heavy...something to consider. I bought four diffusors from a local studio who contracted a carpenter to construct them out of a bulk quantity of balsa wood. They are light enough to be manageable and work as advertised. I'd think about buying more, but the guy realized how much work they are to make and the price will be going up though. I might try my hand at the styrofoam diffusors. They look pretty cool.

[Farmerbrown2200]

Of course I'm absolutely no expert so if this sounds silly let me know[/QUOTE]

not at all...

had this question myself. In the link he painted the foam giving (I presume) more reflective finish (not just for esthetics).

Foam is still alot of work. Cutting foam always ends in a mess for me, no matter how sharp the blade.

[peeceebee]

In terms of reflecting sound, higher frequencies want smooth surfaces to reflect well, lower frequencies want mass to reflect well. So styrofoam will work ok at higher frequencies if the surface is smooth- and the wavelengths at which these sort of designs seem intended to be active are not low frequencies, judging by the dimensions of the elements.

I've got some of the auralex styrofoam diffusers, the work VERY nicely.

Recipe for a great sounding room- diffuse highs, trap lows.

[AlanTide]

You know, the ones with the letters and numbers on them. I am sure there are tons of these in consignment shops all over the place. Buy up several sets and glue them together. They could be painted to any color. What would you mount these to initially though? Thoughts?

[mltamisin]

Kids blocks sounds like a great idea. Styrofoam is used in plenty of diffusive products commercially with great results. I own some styrofoam Skylines and Hemiffusors and both work pretty good.

[Bob Ross]

Originally Posted by Farmerbrown2200

Cutting foam always ends in a mess for me, no matter how sharp the blade.

You don't want to use a blade to cut foam, you want to use a hot wire. Not that that makes it any easier (or safer!) but it is a lot cleaner.

[Cojo]

Originally Posted by tonymite

looks inarestin ...

just wondering ... how does one determine when we need a trap and when we need a diffusor ? What frequency range does the diffusor diffuse at ?

The difference between a trap and a diffusor is that they work in different ways. A trap works by absorbing the energy and ultimatly lets no sound bounce back. The diffusor on the other hand lets the sound bounce back but in differet phases and/or directions. A diffusor is good if you want to reduce standing waves but not dampen the room.

I think the skyline diffusor made by 2"x2" would work in the frequence area of 850Hz - 3400Hz.

/Cojo

[mltamisin]

Dj Who,
I've made similar diffusers with that exact same material. What a strange thing. I went about it a little differently but the end result is the same. Random length 2"x2" styrofoam blocks glued to a masonite board.

[joeq]

Many forms of styrofoam are not only highly flammable, they release toxic gasses when burned. Unless you are certain you have fire ******ant styrofoam, do not use it. The partially-absorptive nature of the material would also make it somewhat sketchy as a diffusor.


For cutting Auralex-type foams, nothing beats an electric carving knife- the kind with two blades that wiggle back and forth. I understand they work for cutting 703 as well. I would imagine that the hot wire would work better for styrofoam since most styrofoam is somewhat 'crumbly' .


I have said this before, but I will say it again- why hasn't some smart company come up with a cheap mass-produced diffusor? Many of these products are stamped out of a molded sheet of plastic and yet cost $200-300 for a 2 foot panel. The argument that they have heavy R & D is baloney when there are public-domain designs and computer models available. At what point of selling $20 pieces of plastic for $200 each is the R & D recouped??

I have held some of these things in my hand and they are just molded plastic. Except for the diffusive properties of the shape, they are not much different in manufacturing terms from a plastic wastebasket you can buy at Target.

[Cojo]

Originally Posted by joeq

I have said this before, but I will say it again- why hasn't some smart company come up with a cheap mass-produced diffusor? Many of these products are stamped out of a molded sheet of plastic and yet cost $200-300 for a 2 foot panel. The argument that they have heavy R & D is baloney when there are public-domain designs and computer models available. At what point of selling $20 pieces of plastic for $200 each is the R & D recouped??

I have held some of these things in my hand and they are just molded plastic. Except for the diffusive properties of the shape, they are not much different in manufacturing terms from a plastic wastebasket you can buy at Target.

Maby one can by one piece and then use it as a mould and start producing cheep Behringer like copies!

/Cojo

[midigod]

The styro won't make an effective diffusor. To be what you want it to be, it needs to be made of wood.

Go here to use 2X2's:

http://www.pmerecords.com/Diffusor.cfm

-Craig

[Saucyjack]

Anyone used the Auralex metrofuser or qfuser products...seems like it might work to spot treat some rooms for not too much$

[joeq]

Originally Posted by Cojo

Maby one can by one piece and then use it as a mould and start producing cheep Behringer like copies!

/Cojo

Indeed.l I would imagine you would have to vary the design somewhat so as to avoid being sued. But the pattern posted at the beginning of this thread seems to be uncopyrighted for example. I think the original source was a BBC document. Build one of those, make a mold of that and bring it to a factory that makes ice cube trays.

I am certainly not advocating doing anything illegal, but I do wonder why somebody doesn't just blow all the competitors out of the water with a reasonably priced product??

[midigod]

Originally Posted by joeq

I am certainly not advocating doing anything illegal, but I do wonder why somebody doesn't just blow all the competitors out of the water with a reasonably priced product??

It's mostly because of the cost of the equipment required to do vacuum molding with that much precision. IIRC, lower-cost molding gear won't do the vertical planes necessary for this type of item, and it's hard to release the mold with those vertical planes anyway.

But if anyone thinks differently, I'd be very happy to work with them to produce masters for mass production.thumbsup There may also be an interesting method of changing the planes to be sloped, but then you're diverging dramatically from the BBC research.

The link to the BBC site is on my aforementioned page of plans.

-Craig

[OMF]

Styrofoam does work. Expanded Styrofoam is what RPG uses for their skyline.
If you DIY you can use High Density Styrofoam, which is even stiffer.
Cost per "Skyline" for materials is under US$12. Have your styrofoam merchant pre-cut the pieces into square rods of desired size. Use GTR E-string to construct Guillotine for hot wire knife.

Total construction time (cutting & Glueing) is about 1 hour per diffusor, assuming you use 13x12 grid.

Sure, it's a bit of a pain, but it beats 200 bucks a panel.

greets

OMF

[thesteve]

The labour time is well worth it compared to buying from Auralex. I suppose the only issue would be mounting any of the wood diffusors from the ceiling because they can be heavy. We built some permanent fixtures and some movable barriers with diffusors on one side and absorption on the other. Really increases the versatility of a room and they look great.

[thesteve]

Wow... did not realize that pic was so big....

[Cojo]

Originally Posted by thesteve

The labour time is well worth it compared to buying from Auralex. I suppose the only issue would be mounting any of the wood diffusors from the ceiling because they can be heavy. We built some permanent fixtures and some movable barriers with diffusors on one side and absorption on the other. Really increases the versatility of a room and they look great.

From what template have you build them? To me they don't seem so random as the other diffeusors I've seen. If true, then maby turn one and other around in 1/4 of a turn randomly to get an even better result!

/Cojo

[midigod]

Originally Posted by OMF

Styrofoam does work. Expanded Styrofoam is what RPG uses for their skyline.

Hi OMF-
That's not true. RPG uses expanded Polystyrene, which is not the same product. Styrofoam is a specific subset of Polystyrene, and is much less dense than the type RPG uses.

-Craig

[mltamisin]

If you're worried about styrofoam's diffusive characteristics then paint them with latex. Increases the diffusion characteristics.

[midigod]

Originally Posted by mltamisin

If you're worried about styrofoam's diffusive characteristics then paint them with latex. Increases the diffusion characteristics.

Only as far down in the audio spectrum as the thickness of the paint dictates. Below that, the waves pass right through. That's why you need density and thickness in a diffusor - so there's mass to reflect the wave.

The paint will only allow true diffusion of the highest frequencies, and there's valid debate over even that. If you're going to the trouble of building one, you would certainly want it to be effective below 10KHz.

[everybody's x]

nice work steve! those look great