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Re: D.I.Y. Diffusers [message #94347 is a reply to message #93398 ]

Fri, 30 September 2005 20:44

compasspnt
Messages: 11506
Registered: December 2004
Location: Compass Point Studios, Na...

Diamond Member

Hey Bill, it's so small I can "bear-ly" see it!

Seriously, is that blocks of compact foam, glued together?

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Re: D.I.Y. Diffusers [message #94355 is a reply to message #94347 ]

Fri, 30 September 2005 22:15

Bill B
Messages: 139
Registered: July 2004

Active Member

har har. I barely got it!
It's built from 1"x 1"x 3/4" blocks of cedar, which is light and easy to work with. I just set up the table saw and had a little cut fest. I thought foam would be too unstable, and probably have to be painted with a gloss to cut down on it's absorbency. The BBC notes suggested square pvc tubing, but I thought that was a little too reflective. In the pic the rough construction was sprayed with a textured paint, but I found that if you do a neat enough job, the plain cedar looks nice and fits just about any rooms' color scheme, being a natural looking element. The variations in the woods' color is nice, and you can use the rough sawn side if you want more texture and possibly 'micro diffusion'.
Total materials per 'unit' (unit=4 12"x 12" sections)is about $14.00. There is no scientific calculation to the unit size, I just figured it had to be at least that large to have a noticeable effect.

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Re: D.I.Y. Diffusers [message #94357 is a reply to message #93622 ]

Fri, 30 September 2005 22:21

Bill B
Messages: 139
Registered: July 2004

Active Member

Bryson wrote on Wed, 28 September 2005 05:21

More like the Romans were using them.

Here're some poly types that I made.

Do you also have the fabric on the walls and ceiling, or is that a good paint match?

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Re: D.I.Y. Diffusers [message #94367 is a reply to message #94357 ]

Fri, 30 September 2005 23:33

12345
Messages: 140
Registered: May 2004

Active Member

I also find that covering the diffusor with a stainless steel mesh (such as they use over microphone capsules) helps the process. Just make sure to ground the mesh, as if it's not grounded it will act like an antenna.

MW

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Re: D.I.Y. Diffusers [message #94410 is a reply to message #94367 ]

Sat, 01 October 2005 09:03

lord
Messages: 206
Registered: May 2004
Location: Boston

Active Member

Should I be grounding my mic stands too?

My god. What about the cymbals?

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Re: D.I.Y. Diffusers [message #94416 is a reply to message #94355 ]

Sat, 01 October 2005 09:44

rdolmat
Messages: 260
Registered: April 2005
Location: Vancouver BC Canada

Active Member

badbear wrote on Fri, 30 September 2005 20:15

Hi Bill!

Those look great! I think I have to pull our my saw and a coffee!!

Cheers
rich

_________________________________
www.digitalsoundmagic.com

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Re: D.I.Y. Diffusers [message #94604 is a reply to message #93401 ]

Sun, 02 October 2005 11:07

Tomas Danko
Messages: 3733
Registered: May 2004
Location: Stockholm, Sweden

Platinum Member

Oh boy do I feel stupid now when I sit here and look at all them egg cartons I put on every wall as well as the ceiling and floor.

And I had been telling my friends I got the same acoustics here as they do at the Fraunhofer Institute.

This is even worse than the allergic reaction I developed towards yokes, having had eggs for breakfast, lunch and dinner the last two months.

"T(Z)= (n1+n2*Z^-1+n2*Z^-2)/(1+d1*z^-1+d2*z^-2)" - Mr. Dan Lavry
"Shaw baa laa raaw, sidle' yaa doot in dee splaa" . Mr Shooby Taylor

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Re: D.I.Y. Diffusers [message #94614 is a reply to message #93398 ]

Sun, 02 October 2005 11:32

compasspnt
Messages: 11506
Registered: December 2004
Location: Compass Point Studios, Na...

Diamond Member

Pretty good "yoke," Tomas!

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Re: D.I.Y. Diffusers [message #94885 is a reply to message #94355 ]

Mon, 03 October 2005 09:20

jimmyjazz
Messages: 1487
Registered: April 2004
Location: Austin, TX

Platinum Member

What does one of your 12" x 12" "units" weigh? How did you hang them?

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Re: D.I.Y. Diffusers [message #95008 is a reply to message #93398 ]

Mon, 03 October 2005 16:43

Bill B
Messages: 139
Registered: July 2004

Active Member

Glues onto a backing 'plate' of 1/4" birch plywood, total weight might be a pound and a half. The plywood weighs about as much as all the cedar blocks. They're light enough to hang with adhesive, but I used stainless countersunk screws into drywall anchors. I used stainless because the tanins in cedar can corrode a zinc or steel screw over time.
I also sprayed the plain cedar diffusors with a satin laquer to make them easier to clean and give them a more finished look. Use Deft brand if you can find it, it has a nice, buttery, warm look to it. I think Lowe's carries it.
I'm going to try some colored water-based stains on my next ones.

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Re: D.I.Y. Diffusers [message #95009 is a reply to message #93398 ]

Mon, 03 October 2005 16:47

Bill B
Messages: 139
Registered: July 2004

Active Member

Another note: Once you see the graph for the layout, you can build faster using different sized blocks. The ones in the picture were made from all 1" blocks, which isn't necessary if you plan ahead.
You could also use the wood diffuser for a reverse mold and cast a fiberglass 'master' for making more 'glass units.

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Re: D.I.Y. Diffusers [message #95190 is a reply to message #95008 ]

Tue, 04 October 2005 09:24

jimmyjazz
Messages: 1487
Registered: April 2004
Location: Austin, TX

Platinum Member

Great info. Thanks.

I'd bet the effort of creating fiberglass versions using the wood as a master would be more trouble than it would be worth. Just make more wood copies. I agree that cutting the individual blocks to length as opposed to stacking 1" blocks makes tons of sense. You just need the recipe ahead of time.

What's the frequency range of your diffusors? How deep into the bass region do they extend?

I had been toying with a very similar construction approach, but planned on using machine screws into stainless inserts (keenserts, etc.) sunk into balsa wood. I hadn't even considered cedar. A natural finish on cedar would add a nice "studio" touch . . . you know, all studios have to be chock full of wood, right?

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Re: D.I.Y. Diffusers [message #95229 is a reply to message #94333 ]

Tue, 04 October 2005 11:31

zetterstroem
Messages: 765
Registered: December 2004
Location: Copenhagen

Gold Member

badbear wrote on Sat, 01 October 2005 01:48

rdolmat wrote on Tue, 27 September 2005 11:59

Hi all!

Anyone have good tips or suggestions on DIY diffusers?

I built some 'skyline' diffusors using the prime number theory posted on the BBC website. As you build more of these they fit togother to create a bigger diffuser, kind of a fractal thing. Here's a pic: (I hope)

do you have a link??

Noting the music industry's complaints that illegal downloading means people are getting their music for free, he said, "Well, why not? It ain't worth nothing anyway." (b.dylan)

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Re: D.I.Y. Diffusers [message #95239 is a reply to message #95229 ]

Tue, 04 October 2005 12:14

Bill B
Messages: 139
Registered: July 2004

Active Member

zetterstroem wrote on Tue, 04 October 2005 12:31

do you have a link??

http://www.bbc.co.uk/rd/pubs/reports/1995-01.pdf

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Re: D.I.Y. Diffusers [message #95242 is a reply to message #95190 ]

Tue, 04 October 2005 12:19

Bill B
Messages: 139
Registered: July 2004

Active Member

jimmyjazz wrote on Tue, 04 October 2005 10:24

What's the frequency range of your diffusors? How deep into the bass region do they extend?

I haven't done any serious testing yet (still building my new room) but I thought I read in the BBC R&D report that they worked down to around 800Hz. I don't know how much lower diffusion would be useful, but at some point I'm sure there's a diminishing return.

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Re: D.I.Y. Diffusers [message #95248 is a reply to message #95239 ]

Tue, 04 October 2005 12:26

jimmyjazz
Messages: 1487
Registered: April 2004
Location: Austin, TX

Platinum Member

http://www.bbc.co.uk/rd/pubs/reports/1990-15.pdf

is referenced in badbear's paper. I haven't dug into it yet, but it appears to describe the theory of diffusers in some detail.

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Recording Engineering & Production: Making records better, not just louder and cheaper. The brightest minds from the creative and scientific world of audio discuss the elements of audio production that interest you most.

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