New Diffuser Technology

[DonH56]

I haven't finished reading the journal article yet but this thread started by Scott Wilkinson over at AVS caught my eye: http://www.avsforum.com/forum/91-au...der-diffuser-10-times-thinner-than-usual.html

Metasurface Schroeder Diffuser is 10 Times Thinner Than Usual
Researchers at North Carolina State University and Nanjing University have developed a remarkable diffuser that is 10 times thinner than usual.

http://www.avsforum.com/metasurface-...thinner-usual/

Essentially a method of using modified cavity resonators to create fairly broadband diffusers that are much thinner (1/20 vs. 1/2 wavelength) than conventional designs.

Key papers/references from the AVS thread:

https://journals.aps.org/prx/abstrac...RevX.7.021034#
https://journals.aps.org/prx/supplem...n2zyf_js-1.pdf

 

[RayDunzl]

Ah Ha!

Just as I always suspected!

 

[Blumlein 88]

So with conventional 2x4 framing, could this be adapted to just replace your sheet rock with the front panel? Looks like over some frequency ranges it could be. Compared to the cost of many of the available diffusors this could turn out to be cheaper.

 

[DonH56]

That's an idea! With RPG out of business good diffusors are harder to find...

 

[Rodney Gold]

I have lasers and CNC machinery ..I will try build one ..I have a low ceiling with "iffy" diffusion and something shallow with the same diffusion a deep cityscape type has would be welcome

 

[Thomas savage]

I have lasers and CNC machinery ..I will try build one ..I have a low ceiling with "iffy" diffusion and something shallow with the same diffusion a deep cityscape type has would be welcome

Nice one, post a picture of what you come up with.

 

[Nightlord]

Haven't read all, so I don't know if it was tested... but perhaps some little dampening could be used in the cavities as well to make it an "abfuser"

 

[Blumlein 88]

Haven't read all, so I don't know if it was tested... but perhaps some little dampening could be used in the cavities as well to make it an "abfuser"

I had that same thought. I have seen similar concrete walls lining generator stations. Slots in the face of the block with the inside similarly shaped. Rock wool was placed inside. The purpose, and it worked well, was to reduce noise of the machinery inside.

 

[Jakob1863]

There was for some time rumour about surprising (means unexpected/unwanted) absorbing properties of diffusors and confirmed accidentially afair around ~1992, but not fully explored. Mechel wrote his analysis paper in 1995 (Mechel F.P.,The wide-angle diffuser - a wide-angle absorber, Acustica, 81, 379-401) and several other research papers followed adding to the theory and providing experimental results as well.

In short, it is possible to get substantial absorbing effects without loosing (too) much of the diffusing virtues by adding a layer with flow resistance. If i am not mistaken, Mechel also provided the idea to build the diffusers with reduced depth by bending the deeper caverns at 90 angles.

 

[Jakob1863]

An Article with some measured results:

Kamisinski et al.; Sound Diffusers with Fabric Covering, Archives of Acoustics Vol. 37, No. 3, pp. 317–322 (2012)

 

[Bjorn]

This is nothing new and not necessarily a good idea. The article below explains why:
http://www.lydogakustikk.no/?p=2706

P.S. RPG isn't out of business. RPG Europe is still operating as normal and RPG in USA will come back under a new owner.

 

[Jakob1863]

There seems to exist a new company founded in 2016:

http://rpgacoustic.com/about/