Fitzcaraldo215
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No collection of wood diffusers would be complete without a Shakti Hallograph.
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Wood acoustic diffusers have become a decorative item - loved the idea!
- Thread starter sarumbear
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OP
- Thread Starter
- #42
Why is the speaker upside down?
Fitzcaraldo215
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No collection of wood diffusers would be complete without a Shakti Hallograph..
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Maybe it sounds “better”.Why is the speaker upside down?
Indeed it is. Never heard of it before. Thank you posting.
I like it especially because it uses my favourite acoustic tool Helmholtz resonator
It's been 3D printed and tested as well... https://pub.dega-akustik.de/ICA2019/data/articles/001008.pdf
OP
- Thread Starter
- #45
A big Bravo to the inventors?
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.
OP
- Thread Starter
- #47
I think 3D printing like they did will be more economical. Not to mention allowing more sizes.
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.
Paper discussing use of metadiffusers in orchestra pits - specifically The Royal Opera House, Covent Garden...
Molds can be very very expensive though
I saw the error in my statement and I clarified it in this post.
Wood acoustic diffusers have become a decorative item - loved the idea!
No collection of wood diffusers would be complete without a Shakti Hallograph.
www.audiosciencereview.com
OP
- Thread Starter
- #53
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.
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.
DanielT
Major Contributor
Sarumbear, what do you think about this? Diffusers made of cast pipe in cardboard:
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www.lifewire.com
A Simple, Cheap Way to Great Room Acoustics
A step-by-step tutorial on how to make and install your own audio diffusers for great acoustics at home
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
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
Lightweight skyline diffusers made of expanded polystyrene than can be suspended using hook and loop (Velcro)....
www.rpgeurope.com
RPG Skyline - Acoustic Products
RPG Skyline Diffusor, the original Primitive Root Diffusor.
www.rpgeurope.com
MRC01
Major Contributor
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.
MRC01
Major Contributor
yep, that's the kind of guideline I was looking for.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!
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