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Wood acoustic diffusers have become a decorative item - loved the idea!

No collection of wood diffusers would be complete without a Shakti Hallograph.

1667942662048.jpeg
 
sarumbear said:
A big Bravo to the inventors?
Click to expand...
What would be ace is to make a fiberglass mould and then use vacuum to press a sheet of heated plastic over the mould and make them in quantity and economically. Make diffusers that is. Not helmholtz resonators.
 
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Doodski said:
What would be ace is to make a fiberglass mould and then use vacuum to press a sheet of heated plastic over the mould and make them in quantity and economically.
Click to expand...
I think 3D printing like they did will be more economical. Not to mention allowing more sizes.
 
sarumbear said:
I think 3D printing like they did will be more economical. Not to mention allowing more sizes.
Click to expand...
For a helmholtz resonator 3D printing is the solution but I think for a 1m x 2m or larger diffuser panel a vacuum indented lightweight thin plastic material is easily shipped at the weight of maybe 5 pounds.
 
Doodski said:
For a helmholtz resonator 3D printing is the solution but I think for a 1m x 2m or larger diffuser panel a vacuum indented lightweight thin plastic material is easily shipped at the weight of maybe 5 pounds.
Click to expand...
Molds can be very very expensive though
 
Doodski said:
For a helmholtz resonator 3D printing is the solution but I think for a 1m x 2m or larger diffuser panel a vacuum indented lightweight thin plastic material is easily shipped at the weight of maybe 5 pounds.
Click to expand...

I didn't think you could vacuum form something this shape (you could extrude it)...

1667943882569.png
 
Doodski said:
For a helmholtz resonator 3D printing is the solution but I think for a 1m x 2m or larger diffuser panel a vacuum indented lightweight thin plastic material is easily shipped at the weight of maybe 5 pounds.
Click to expand...
It is a composite of Helmholtz resonator and diffuser. It was designed to be customise for each job. A single model that will be stocked is not what the device is designed for.
 
MarcosCh said:
Molds can be very very expensive though.
Click to expand...
After making several or more diffusers a mould would be economical and could be used to resale more diffusers which apparently have a lack of packaged product availability in the world's market.
 
sarumbear said:
It is a composite of Helmholtz resonator and diffuser. It was designed to be customise for each job. A single model that will be stocked is not what the device is designed for.
Click to expand...
Could a end user buy various sizes of packaged and ready for use lightweight panels made from ~2.5+mm thick plastic and then assemble them into larger sizes as is required for a environment's special needs. That would get close to the goal parameters?
 
This thread rekindled my interest in messing with metamaterials on my 3D printer... this paper describes something that I think is very feasible (the prints they show aren't exactly rocket science) and seems to work already in the <150hz range with 10cm or thinner panels.

https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.6.064025

@sarumbear per your earlier question, is 27kg heavy? Yeah it's heavy to hang on the wall! Especially if you rent, the added cost of such a thing is around $200+ when you move out and your landlord charges you to repaint the wall. :) Lightweight diffusors can be attached using removable adhesives like command strips, which removes an entire logistical obstacle to treating the room.


Add these with some metadiffusers or absorbers and maybe a 3D printer is looking like the ticket to new vistas of room treatment...

@Doodski: vacuum-forming this type of thing wouldn't be that hard, but you might need a very large vacuum former, and those things aren't super cheap. Also, you may not be able to use wood for the mold, and you'd need to very slightly taper the sides so the mold could release properly. Vacuum forming processes I've seen were for much smaller parts, like 12" on a side or something. Larger machines probably exist but I haven't seen one personally. On the other hand, they probably use them for making jacuzzis and stuff... so maybe ask your local jacuzzi factory for some shop time ;)
 
sarumbear said:
... As an acoustician I am tired to tell people not to think room treatment only as absorption. In most small rooms absorption often creates more issues than it solves. Diffusion is a better solution. ...
Diffusers on the other hand stops reflections by scattering the sound so that reflections occur at very high frequencies and hence at less amplitude.
Click to expand...
Can you share guidelines on how to approximate the frequencies a diffusor will scatter, based on the size or shape of its protuberences?

For example it may be based on sound wavelength, like 1' = 1100 Hz, 6" = 2200 Hz, etc. That is, if its edges (or more generally speaking protuberences) are that big/thick, those are the frequencies they will scatter. That's just an example of the kind of guideline that would be useful; I don't know what the guideline actually is. Maybe it's half wavelengths or something else.
 
sarumbear said:
If you look at various charts you will see that the effectiveness curve is not steep. As there’s only one element at work the curve is 6dB/octave I.E. it is 50% effective at half the frequency you calculated and 30% at a third.
...
However, 5cm is very small for a diffuser. There are picture frames deeper than that! :) if you use 10cm at least you should expect effectiveness at half of the audible range. Go another 5cm and you cover 2/3rd.
Click to expand...
yep, that's the kind of guideline I was looking for.
 
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