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DIY Sound Diffusers—Free Blueprints—Slim, Optimized DIY Diffuser Designs (+Fractals)
Old 11th July 2018
  #841
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Is there someone here that emailed Tim for the A1LeanFractal (not fuser) plans and would be willing to send them on to me? (Looks like he didn't want to post those online to protect his IP, but was sending them to folks via email). I sent him an email but no response yet and it looks like he hasn't logged in here in a while... Curious about the fractal dimensions. Thanks!
Old 15th May 2019
  #842
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AudioWonderland's Avatar
 

Does the wood for this matter? Will standard 1/2" pine ply wood suffice our do you need something specific?
Old 15th May 2019
  #843
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Quote:
Originally Posted by ths61 View Post
@ Arqen , Would a routed profile something like this triple bead and flute bit be a good approximation for a fractal implementation ?

3/16" deep and 1 3/8" wide.

Also, how much coverage is required to be useful ?

TIA

I think profiles like this would work if you can apply them at angles and mix it up with other shapes/profiles.

Anything to "Mix it up" often turns out well. Fractal is one method of trying to optimize how it's mixed up. I like a mixture of fabric, Stone, Wood, etc.

I wonder how a fractal difuser out of granet would sound!
Old 15th May 2019
  #844
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Quote:
I think profiles like this would work if you can apply them at angles and mix it up with other shapes/profiles
.

I don't see how a round profile would work for wells that are supposed to be square. Part of the principle of operation of a diffuser is that the incoming sound wave is able to enter the well, hit the (flat) bottom, and be reflected back up again, resulting in a time delay (and thus a phase shift). With curved sidewalls and a curved bottom for the well, I don't see how that reflection would happen...

That said, I would imagine that there must be similar router bits that are able to cut square-bottom, sheer-sided grooves, rather than rounded ones... ? Of course, the bit would have to cut to the exact correct dimensions...

Quote:
Fractal is one method of trying to optimize how it's mixed up.
Well, yeah.. I suppose! As long as the "mixing up" still follows the math behind how diffusers work. You can't just use any old random shape....

Quote:
I wonder how a fractal difuser out of granet would sound!
Just like one made out of any other material, actually... It's not the material that causes the diffusion, but the carefully crafted shape.

- Stuart -
Old 15th May 2019
  #845
Gear Addict
 

For a fractal diffuser I would use a small diameter straight router bit instead, Ø 6 mm or 1/4" or so is easier to control than larger bits and also less risky to operate. Together with "shims" in suitable thicknesses + a straight piece of wood along the side of the router machine, you can controll width and depth of each part of the diffuser front. Insert shims one at a time to widen the groove. Reset the bit depth when one groove is done and start with the next groove.

With a good table saw with a height adjustable blade, a straight edge + shims you can do the same. Clean any debris in the groove with a chisel.
Old 15th May 2019
  #846
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Bstapper's Avatar
 

Quote:
Originally Posted by Soundman2020 View Post
.

Just like one made out of any other material, actually... It's not the material that causes the diffusion, but the carefully crafted shape.

- Stuart -
You underestimate the necessity of mass.

If your statement were true then paper plates would work if molded into the desired shape.
Old 15th May 2019
  #847
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Quote:
Originally Posted by Bstapper View Post
You underestimate the necessity of mass.
I don't think so...

It's a common misconception that diffusers have to be massively heavy to work: the principle of operation is not related to mass: Any reasonably rigid material will work.

Quote:
If your statement were true then paper plates would work if molded into the desired shape.
Actually, they probably would!

You don't need much mass on a diffuser: the ones molded from EPS and other plastics actually work quite well, and weigh very little. They look awful unpainted, sure, but they do work. What's most important is the correct shape, and air-tight wells. Mass is not relevant (within reason!)

You might find this thread interesting:

Diffusors: opinions about EPS polystyrene?

- Stuart -
Old 15th May 2019
  #848
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Paper plates are not "within reason". I'm not sure that product you linked to is either, but I like the fact it looks like it is doing something.

Cheers,
Brock
Old 15th May 2019
  #849
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Quote:
Originally Posted by Bstapper View Post
Paper plates are not "within reason".
The density of waxed paper is around 700 kg/m3. The density of EPS is around 30 kg/m3 (at the low end of the range). A typical paper plate is about 1mm thick, so it has roughly the same mass as an inch of EPS. Diffusers molded from EPS are often a lot thinner than an inch... So yeah, a folded paper plate would do fine. Might not look very pretty: it would need a coat of paint, maybe, to make it nicer, but it would diffuse. It would also absorb probably, from the membrane effect, which might be unwanted... but then again, many diffusers also absorb in unwanted ways, so there's no difference there. And you might also be able to put that absorption to good use.

Quote:
I'm not sure that product you linked to is either, but I like the fact it looks like it is doing something.
If you actually click on that link, you'll find out that it doesn't take you to a product: in fact, it takes you to a thread here on GS, discussing in general the issue of diffusers made from EPS and similar materials. There are several mentions of various commercial products on that thread.

If you don't think those products are "within reason", then you should probably take that up with RPG, GIK acoustics, Jens, Thomann, etc. I'm sure Dr. D'Antonio and Glenn Kuras would love to hear your opinion on why EPS diffusers are not "within reason" and only "look like they are doing something"...

Anyway, getting back to the point: High mass is not necessary for a diffuser to work. Shape is what counts. Any reasonably stiff and reflective material can be used to make them.

- Stuart -
Old 16th May 2019
  #850
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I was referring specifically to the 8-pack of .$89 diffusion discussed in that link.

I don't have to guess whether the product in question is "within reason" or not. I automatically assume that it is as soon as no quantifiable published performance specification is available.

But I'm not going to sit here and argue about the merits of using paper plates folded into the proper shape as a viable means of effective diffusion.

Carry on,
Brock
Old 16th May 2019
  #851
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Quote:
Originally Posted by Soundman2020 View Post
.

I don't see how a round profile would work for wells that are supposed to be square. Part of the principle of operation of a diffuser is that the incoming sound wave is able to enter the well, hit the (flat) bottom, and be reflected back up again, resulting in a time delay (and thus a phase shift). With curved sidewalls and a curved bottom for the well, I don't see how that reflection would happen...

That said, I would imagine that there must be similar router bits that are able to cut square-bottom, sheer-sided grooves, rather than rounded ones... ? Of course, the bit would have to cut to the exact correct dimensions...

Well, yeah.. I suppose! As long as the "mixing up" still follows the math behind how diffusers work. You can't just use any old random shape....

Just like one made out of any other material, actually... It's not the material that causes the diffusion, but the carefully crafted shape.

- Stuart -
Thank you for some real answers! very cool.
Old 30th May 2019
  #852
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I was reading this great thread and I have a simple question regarding panel measurement/prediction:

Why 3.6m as a measurement width standard?

"The rest of the table keeps all the test sample widths the same at about 3.6 m to allow ready comparison. When comparing other diffusers in the table, it is important to compare like with like, for example to ensure that the diffusers being compared have the same maximum depth. Trevor J. Cox - Acoustic Absorbers and Diffusers: Theory, Design and Application

Why should we mesure (or calculate) a panel of 3.6m to estimate its behaviour if only a panel of 1.2m is used (so 33,33% of the measured panel)?
Is that important to measure/calculate a 3.6m panel if we don't compare to others?

I mean, if I play with Reflex for a 1.2 m panel design. Looks awesome. But when I calculate for a 3.6 m it's not great. Should I care since the panel will be only 1.2m width?
Old 25th August 2019
  #853
Gear Head
Quote:
Originally Posted by Arqen View Post
....

Enjoy the blueprints!

Tim

P.S. I’ll update this thread when I post more DIY diffuser resources. So stay tuned!
(to download the designs, visit the blue link above)
Hi Tim,

I see the Diffractal base is different than the LeanFuser base.

[0 40 70 60 80 50 10] vs [0, 40, 50, 30, 50, 40, 0]

Will a Diffractal base work better than a LeanFuser base (considering it is deeper (80mm versus 50mm) and asymmetric (no repeats versus 3 repeats in the 7 bays)) without the 2nd layer of narrow diffractal strips added to it ?

I would assume it would perform better than the LeanFuser and not quite as good as the Diffractal Diffuser.

Thanks much.

P.S.

It looks like some people made "nested LeanFusers" instead of "nested Diffractals".
Old 26th August 2019
  #854
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Quote:
Originally Posted by JayPee View Post
I was reading this great thread and I have a simple question regarding panel measurement/prediction:

Why 3.6m as a measurement width standard?

"The rest of the table keeps all the test sample widths the same at about 3.6 m to allow ready comparison. When comparing other diffusers in the table, it is important to compare like with like, for example to ensure that the diffusers being compared have the same maximum depth. Trevor J. Cox - Acoustic Absorbers and Diffusers: Theory, Design and Application

Why should we mesure (or calculate) a panel of 3.6m to estimate its behaviour if only a panel of 1.2m is used (so 33,33% of the measured panel)?
Is that important to measure/calculate a 3.6m panel if we don't compare to others?

I mean, if I play with Reflex for a 1.2 m panel design. Looks awesome. But when I calculate for a 3.6 m it's not great. Should I care since the panel will be only 1.2m width?
Anyone?
Old 3rd September 2019
  #855
Gear Addict
 

Quote:
Originally Posted by JayPee View Post
Anyone?
What exactly are you trying to simulate?

Your critical distance from the array (ie how far from your monitoring position)

Or the physical width of the array ?

ie that width suggests you either you have created 3 panel array thats approx 1.2m wide in physical dimensions or one of unknown that your desired listening distance from will be 1.2m?

Or have you modelled a different array and your using 1.2m then 3.6 m as the distance between the array and the listener ?

clarifying this will help answer i believe
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