Need Help With DIY Diffuser Design...

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MoreSpaceEcho
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Re: Need Help With DIY Diffuser Design...

Post by MoreSpaceEcho » Mon Aug 03, 2020 4:41 pm

I will try to dig up some info, I know I saw Thomas Jounjean from Northward Acoustics talking about it, and he's the man for studio design afaic.

Anyway for DIY those polys are tough to beat. Cheap, easy to make, light, cool looking, and they really work. To give you an idea of how effective they are:

Back at my old loft, out in the main room there was a wicked flutter echo, it was loud and it raaaaaaaaaaang. Putting up 2 2'x4' polys, one on each side wall, totally fixed it. You can't see them in this pic (they're up high), but the left and right walls here:

Image

It was a big room and putting polys on a pretty small percentage of the wall space made a huge difference.

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Re: Need Help With DIY Diffuser Design...

Post by The Scum » Mon Aug 03, 2020 4:55 pm

The BBC tried to make a thin-wall version of their diffusor in 1995:

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

The well depth made most molding techniques out of reach, they wound up with glass reinforced polymer.

The test data indicates it's not much of an absorber, but an OK diffusor at the wavelengths that relate to the basic geometry.

It looks like a number of companies are making vacuum-formed plastic diffusors, for example the Auralex T-fusor.
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Re: Need Help With DIY Diffuser Design...

Post by Here&ThereStudios » Mon Aug 03, 2020 6:03 pm

Lovely! Thanks for all the replies I'll see what I can get going with the curved panels. I bet this is going to get a lot of people into the garage!

MoreSpaceEcho
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Re: Need Help With DIY Diffuser Design...

Post by MoreSpaceEcho » Mon Aug 03, 2020 8:21 pm

Couple things I should mention, probably obvious but just in case:

make the frame 47" INSIDE. It'll measure 48.5" on the outside. You can of course make the panel any width you want, just make the frame an inch narrower.

I just screwed the frame together, but add some L-brackets in the corners, and a crossbrace (maybe 2 if you're making one bigger than 4' high) in the back.

Stain the pieces before you put the panel in the frame.

MoreSpaceEcho
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Re: Need Help With DIY Diffuser Design...

Post by MoreSpaceEcho » Tue Aug 04, 2020 12:28 pm

Found a pic where you can see how tiny the poly looks on the wall:

Image

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Re: Need Help With DIY Diffuser Design...

Post by digitaldrummer » Tue Aug 04, 2020 12:32 pm

MoreSpaceEcho wrote:
Mon Aug 03, 2020 1:54 pm
I'm far from an expert but AFAIK real lightweight stuff doesn't work for diffusors, you need something with some actual mass.
I am far from a physicist or acoustic engineer myself... (but, hey I did read the Rod Gervais book so I guess I'm qualified to say anything on the internet...). Anyway, I thought with an absorber, you want mass, especially for absorbing the lower frequencies. For diffusers, we are just trying to randomly scatter the reflections right? so I would think a more reflective surface is key, but mass not so necessary. Diffusers are used when you don't want to deaden the room (or shorten the reverb time) but need to reduce ringing or flutter. So that's my understanding, but I could be wrong...
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Re: Need Help With DIY Diffuser Design...

Post by Scodiddly » Tue Aug 04, 2020 1:23 pm

I'd have to dig out a big heavy book to verify this, but I think the deal with those curved poly diffusers is that at lower frequencies they flex and absorb, especially if backed with fiberglass or something. Higher frequencies get scattered.

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Re: Need Help With DIY Diffuser Design...

Post by MoreSpaceEcho » Tue Aug 04, 2020 1:46 pm

digitaldrummer wrote:
Tue Aug 04, 2020 12:32 pm
For diffusers, we are just trying to randomly scatter the reflections right?
Right, but I think real lightweight QRD diffusors are only effective on high frequencies, they're not working in the mids, because those freqs are big enough to pass through them/deflect around them/whatever it is waves do.

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Re: Need Help With DIY Diffuser Design...

Post by trodden » Tue Aug 04, 2020 3:50 pm

MoreSpaceEcho wrote:
Mon Aug 03, 2020 4:41 pm
I will try to dig up some info, I know I saw Thomas Jounjean from Northward Acoustics talking about it, and he's the man for studio design afaic.

Anyway for DIY those polys are tough to beat. Cheap, easy to make, light, cool looking, and they really work. To give you an idea of how effective they are:

Back at my old loft, out in the main room there was a wicked flutter echo, it was loud and it raaaaaaaaaaang. Putting up 2 2'x4' polys, one on each side wall, totally fixed it. You can't see them in this pic (they're up high), but the left and right walls here:

Image

It was a big room and putting polys on a pretty small percentage of the wall space made a huge difference.
That place was so awesome.

MoreSpaceEcho
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Re: Need Help With DIY Diffuser Design...

Post by MoreSpaceEcho » Tue Aug 04, 2020 3:57 pm

It was. Came with a whole lot of problems but what a great space.

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Re: Need Help With DIY Diffuser Design...

Post by Colorblind » Tue Aug 04, 2020 5:32 pm

I built a couple of these to get rid of flutter echo between the floor and ceiling. Super easy to build using 1/2" plywood, and works like a charm.
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roscoenyc
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Re: Need Help With DIY Diffuser Design...

Post by roscoenyc » Thu Aug 06, 2020 3:17 pm

digitaldrummer wrote:
Mon Aug 03, 2020 6:39 am
I know its not as much fun as making it, but what about something lightweight and ready-made like this?

https://www.gikacoustics.com/product/2a ... bsorber-2/

and you can mount it like a picture frame so if you move, you can take it with you. you could also try a couple and add-on if you need more the big wooden diffuser's can get pretty heavy.

otherwise, if you just need absorption, Owens Corning 703 works well (once you wrap it with cloth) - you can hang it on the walls for mid-high absorption, or stack it in the corners for bass trap ("superchunk" style).
We've got some of those things on the back wall of our room. They are very light weight, not that expensive and they do the trick diffusion-wise at our place.

Image

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Re: Need Help With DIY Diffuser Design...

Post by Scodiddly » Thu Aug 06, 2020 4:18 pm

roscoenyc wrote:
Thu Aug 06, 2020 3:17 pm
Image
You've got a Meyer CP-10!!!

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roscoenyc
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Re: Need Help With DIY Diffuser Design...

Post by roscoenyc » Fri Aug 07, 2020 6:22 am

We've got 2 of the Meyer CP10's.
Poor mans Sontec!
Really fabulous piece.

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