[simoon]

I am sure this has been asked before, but I could not find the correct search terms.

I'm not exactly sure how to phrase this question, or if I am even asking the right question, but here goes.

If a panel has the correct geometry, say, a skyline diffuser, but it is made out of soft foam, will it act as a diffuser?

Seems to me, if the material has absorptive properties, like foam, that will mostly override the shape of the surface. How will the sound diffuse, if it being absorbed by the foam?

[Charles Xavier]

Polystyrene foam is not soft and works very well as a diffuser

[TRADERXFAN]

Yeah, don't use soft foam... use firm foam. You can add a coating to make it more reflective and therefore useful as a diffusor.

[simoon]

You both confirmed my thinking.

What would be a good coating? Relatively easy to apply, effective and not destroy the foam.

Thanks!

[rollo]

Polystyrene foam is not soft and works very well as a diffuser

  Bought the unpainted ones and wasted my money. Edges broke easily and are delicate when installing. My experience.
Try painted or GIK panels.

charles

[JakeJ]

Wonderfully inexpensive latex interior paint.  Hallelujah!

I have heard the medium to dark browns have a more neutral sound.  JK.

  Bought the unpainted ones and wasted my money. Edges broke easily and are delicate when installing. My experience.
Try painted or GIK panels.

charles

Not my experience with the ones I bought.  YMMV.

[Mariusz Uszynski]

Would you consider styrofoam diffusers?They come in black or white colours.


https://vicoustic.com/product/multifuser-dc3?g=0&multifuser-dc2-finishes=Black

[HAL]

Polystyrene foam is not soft and works very well as a diffuser

I bought the Behr coffee color painted ones and have worked well.  Just did LSAF2023 in Dallas TX with false walls with the foam hung on it.  Worked very well.

[JakeJ]

Would you consider styrofoam diffusers?They come in black or white colours.


https://vicoustic.com/product/multifuser-dc3?g=0&multifuser-dc2-finishes=Black

I could not find prices on these but I'm guessing well above my pay grade since the mfr website sends me to one of the most expensive B&M's in Seattle.  I may DIY some of these types of diffuser down the road.

[Mariusz Uszynski]

I could not find prices on these but I'm guessing well above my pay grade since the mfr website sends me to one of the most expensive B&M's in Seattle.  I may DIY some of these types of diffuser down the road.

I did my room in 2020, I paid $105 (canadian) per panel.Size 59X59cm.You can find dealers in North America.I purchased mine in Canada.

[TRADERXFAN]

I think this is worth a look...
https://gearspace.com/board/studio-building-acoustics/619846-diffusors-opinions-about-eps-polystyrene.html

[JLM]

Acoustic materials cannot be judged by appearances, must look into test results.  Foam (all types) are nearly acoustically transparent at all frequencies, so they don't work as an absorbent or diffuser. 

[HAL]

Does this acoustical test data include painting the closed cell styrofoam surface to make it reflective? 

[TRADERXFAN]

In the link I sent they talk about the density of foam importance. So I do think higher density foams are not transparent. Even Geddes uses foam [and patented that method] to absorb HOMs on the compression horn in his design. And that is a low density... just food for thought. Foam is can have its uses to audio wavelengths.

Also in that link they had some absorption figures - not sure if it was from a 3rd party testing facility but similar to their reports.

Jens has a great reputation in studio design work so I tend to believe he has an effective product based on taht. Plus our fellow industry circle Gik does use it too...
https://www.gikacoustics.com/product-category/acoustic-foam/

Don't fear the foam! lol

[adding: obviously you don't want absoprtion when you are making a diffusor... just mentioning that since we kind of shifted to whether foam is transparent]

[S Clark]

The Pi Audio hard styrofoam diffusers work very well.  I've used them for years.  If you snap off an edge by being careless, 5 minutes and some Elmer's glue puts it right.  Use a toothpick to hold the piece in place. 

[HAL]

Scott,
Agree.  Have a few versions of the styrofoam diffusor panels and all work very well.

[rollo]

  Hal those are different than the ones I had. Mine had sharp edges that broke off as careful as I was. Now I use the GR way of drapes on front wall and slightly up the front side wall.  Not going back.

charles

[timind]

  Hal those are different than the ones I had. Mine had sharp edges that broke off as careful as I was. Now I use the GR way of drapes on front wall and slightly up the front side wall.  Not going back.

charles

These are the panels you're referring to?


I've had these for a couple years now without a problem. I repainted mine to match the walls.

[S Clark]

Acoustic materials cannot be judged by appearances, must look into test results.  Foam (all types) are nearly acoustically transparent at all frequencies, so they don't work as an absorbent or diffuser.

All types?? At nearly all frequencies???? This is incorrect.

[JLM]

The best diffusers I've found are DIY:  prerecords.com/Diffusor.cfm

They are quadratic in design and made of wooden blocks of varying lengths up to 7.5 inches long.  An 18 inch square section weighs 23 pounds, which explains why manufacturers use foam or hollow plastic.  Recommend painting the blocks to decrease absorption.  At 7.5 inches deep their effectiveness be limited to midrange frequencies.