The No.1 Website for Pro Audio
Diffusors: opinions about EPS polystyrene?
Old 9th June 2011
  #1
Gear Nut
 

Diffusors: opinions about EPS polystyrene?

Hello,

I'd like to reduce flutter echo in my control room without deadening it too much. I've found some pretty cheap polystyrene diffusors (EPS). I don't know if that kind of material is effective, is there anyone who know? Thank you!

examples:

http://www.thomann.de/fr/the_takusti...sor_8erset.htm
Old 9th June 2011
  #2
Gear Guru
 
Glenn Kuras's Avatar
I don't see the range of how they diffuse/scatter, but at that thickness I would think only higher upper end. I like to see diffusors around 5" or deeper to help with more of the mids and up.
Old 9th June 2011
  #3
Lives for gear
 
Jens Eklund's Avatar
EPS is an effective material to make diffusers of since its relatively cheap, lightweight and reflective, especially if painted and mounted properly. Naturally, not all diffusers made of EPS are “good”. The shape and depth determines the performance.

The downside of EPS, especially if low density (below approx 30 kg/m³) is the durability which cannot compete with wood or steel but the price of ready made diffusers in these materials is usually 5-10 times higher.

Another benefit of EPS is the possibility to produce relatively complex shapes that allows for optimizing performance with new BEM-modeling software. My upcoming model, "Optiffuser" is a result of this:

Diffusors: opinions about EPS polystyrene?-optiffuser-4-panels-painted-1000x600.jpg
Diffusors: opinions about EPS polystyrene?-optiffuser-close-up-unpainted-1000x700.jpg
Diffusors: opinions about EPS polystyrene?-optiffuser-20on-20rear-20wall-20in-20lede-20control-20room-1-.jpg
Diffusors: opinions about EPS polystyrene?-optiffuser-diffusion-coefficients-bem-1200x800.gif

Manual
Old 9th June 2011
  #4
Gear Guru
 
Glenn Kuras's Avatar
Quote:
The downside of EPS, especially if low density (below approx 30 kg/m³) is the durability which cannot compete with wood or steel but the price of ready made diffusers in these materials are usually 5-10 times higher.
As a company that sells both that is pretty much spot on. It really comes down to what you are going for. I have some customers that would never spend the money on say our Q7D (wood) and others that would never use EPS because of the looks. Neither is right or wrong, but what you are going for.
Old 9th June 2011
  #5
Lives for gear
 
Jens Eklund's Avatar
A common misconception about diffusers made of EPS is that they don’t reflect as good as wood or other dense materials. This can be true if low-density EPS is used and not painted. I did some measurements on my panels and the effect of a coat of paint is obvious:

Diffusors: opinions about EPS polystyrene?-optiffuser-absorption-coefficients.gif

In the low frequency region, the only thing affecting absorption is the mounting, which can actually be used to create a membrane absorber to battle modal issues. More information on the effects of mounting and the membrane effect here:
Flooring question
Old 9th June 2011
  #6
Gear Nut
 

Very interesting. I guessed it's only diffusing highs which is enough for me since I just want to get rid of a high pitched flutter echo. I already have bass traps and acoustics panels (242 and 244 from GIK).

Concerning durability, if nobody touches them it should be ok on the long run. It won't fall apart by itself ;-)

I'm sure how EPS looks at a distance, is it sleek when painted? Does it look like plastic or is it obvious that it's polystyrene say on a wooden wall?

If you guys could post a few pictures it would be great! thank you!
Old 9th June 2011
  #7
Gear Nut
 

I've seen your pictures Jens, really nice! But it's hard to tell since it's still white.
Old 9th June 2011
  #8
Lives for gear
 
Jens Eklund's Avatar
Any diffuser with a total depth of only 1 dm (and if EPS, an effective depth of a few cm less) will only be effective in the midrange up. To be able to achieve good diffusion in the low mid, it need to be deeper.

Assuming the density is above approx. 30 kg/m³, EPS is quite sturdy but if you decide to throw your guitar amp at it, it will definitely brake.

Here is a close-up of a coated EPS diffuser, a previous model of mine (but using the same EPS, 42 kg/m³):



If enough layers of paint (2 or more depending on the paint used), the EPS texture will be invisible so it could be anything underneath.
Old 9th June 2011
  #9
Gear Guru
 
Glenn Kuras's Avatar
It does look nice when painted, but still not as nice as wood. See the following pages to compare.
GIK Acoustics. Acoustic Panels and Bass Traps. (wood)
GIK Acoustics. Acoustic Panels and Bass Traps. (EPS and wood)
GIK GridFusor. GIK Acoustics. Acoustic Panels and Bass Traps. (just EPS)
Old 9th June 2011
  #10
Gear Nut
 

Nice.

Glenn: I think the shape looks nice by itself Of course it's not as smooth as a wooden one but at least on your pictures it's good looking.

Jens: Thank you very much for your picture. Honestly if I didn't know it's EPS I couldn't tell, it could be wood! Really fine job!

The link in my first post is for diffusors 2.75 inches thick, sounds like it's too thin when compared to what you're using. Also, I've checked GIK website to check their product, do you sell diffusors as well Jens?

And by the way, have you tried to varnish the diffusers to make them look more like wood/plastic? Is it possible when painted?
Old 9th June 2011
  #11
Lives for gear
 
Jens Eklund's Avatar
A 70mm deep diffuser is not going to diffuse much below the high midrange no matter how good the shape is. Add to this that the effective depth is even shallower since the base of an EPS diffuser need to be a certain thickness in order not to brake.

As long as the paint used supports the features needed, I see no problem in achieving almost any finish. You can paint a diffuser with a brush but I strongly recommend spray painting. The shape is a bit tricky to cover manually.

I currently only sell to my clients but hopefully, these will soon be available at some stores (at least in Sweden). I have sold some to other nations but shipping is a tad pricey.
Old 9th June 2011
  #12
Gear Nut
 

Makes sense. That's unfortunate shipping is so expensive... Just came across this one, thickness is 16cm! What do you think? There's no frequency chart prodived and the shape seems too smooth to diffuse properly, am I wrong?

http://www.thomann.de/fr/the_takusti...asdiffusor.htm
Old 9th June 2011
  #13
Lives for gear
 
Jens Eklund's Avatar
Quote:
Originally Posted by Roswell View Post
Makes sense. That's unfortunate shipping is so expensive... Just came across this one, thickness is 16cm! What do you think? There's no frequency chart prodived and the shape seems too smooth to diffuse properly, am I wrong?

THE T.AKUSTIK SD-2 RAS-DIFFUSOR - Cyberstore Thomann Français
THE T.AKUSTIK SD-2 RAS-DIFFUSOR - Anyone using this? reckon its any good?

Old 9th June 2011
  #14
Gear Nut
 

Nice thank you!
Old 9th June 2011
  #15
Gear Nut
 

So as an acoustician, would you say it's expensive for what it does?
Old 9th June 2011
  #16
Lives for gear
 
Jens Eklund's Avatar
Considering the suspected minimum temporal diffusion; yes.
Old 9th June 2011
  #17
Gear Nut
 

Good to know! I should try the DIY approach then if I want to keep the expense low because the problem is always shipping charges, unfortunately!

Maybe with MDF with a basic and trusted design.
Old 9th June 2011
  #18
Lives for gear
 
Jens Eklund's Avatar
If you have the time, DIY is usually the cheapest option. heh

QRDude: Quadratic Residue Diffuser calculator
Old 9th June 2011
  #19
Gear Guru
 
Glenn Kuras's Avatar
Quote:
Originally Posted by Roswell View Post
Good to know! I should try the DIY approach then if I want to keep the expense low because the problem is always shipping charges, unfortunately!

Maybe with MDF with a basic and trusted design.
We don't even ship to Zeta Reticuli.
Old 9th June 2011
  #20
Lives for gear
 
Jens Eklund's Avatar
Quote:
Originally Posted by Roswell View Post
That's unfortunate shipping is so expensive...
I’m considering cutting my profit when selling to other countries (but still only Europe) in order to compensate for the shipping cost. Also, avoiding the retailers markup (since this would be a direct sale), this further improves the situation. In some cases maybe even compensates completely if more that one pack. Drop me a PM if you’re interested or if you want more info on the Optiffuser.
Old 9th June 2011
  #21
Gear Guru
 
Glenn Kuras's Avatar
Bump for Jens. lol lol
Old 9th June 2011
  #22
Lives for gear
 
Jens Eklund's Avatar
Quote:
Originally Posted by Glenn Kuras View Post
Bump so Jens gets some more advertising face. lol lol
Look who’s talking! How many times per day do you post a link to your company?

Old 9th June 2011
  #23
Gear Addict
 

Thats a good finish, concidering it being applied to such an irregular shape
Old 9th June 2011
  #24
Gear Addict
 

Quote:
Does it look like plastic or is it obvious that it's polystyrene say on a wooden wall?
You have many imitations of crown mouldings made out of polystyrene which looks fine against wood when painted
Old 9th June 2011
  #25
Gear Guru
 
Glenn Kuras's Avatar
Quote:
Originally Posted by Jens Eklund View Post
Look who’s talking! How many times per day do you post a link to your company?

Busted!! Nice stuff btw.
Old 11th August 2011
  #26
Here for the gear
 

Has anyone considered coating something like resin on an EPS diffusor before painting? I just built several 2D prds out of EPS and I'm trying to decide whether to simply paint it or do something more fancy.

Last edited by hom3r; 11th August 2011 at 01:29 AM.. Reason: clarification
Old 11th August 2011
  #27
Lives for gear
 

Quote:
Originally Posted by hom3r View Post
Has anyone considered coating something like resin on an EPS diffusor before painting? I just built several 2D prds out of EPS and I'm trying to decide whether to simply paint it or do something more fancy.
Jens will likely chime in - but he has measured differences between painted and un-painted. the painted seemed to be much more reflective (which improved the diff/scattering coefficients, if i recall correctely (didnt bookmark the post)) - but let him confirm.
Old 11th August 2011
  #28
Lives for gear
 

by the way, where does one procure EPS polystyrene?

are you getting pre-cut pieces of desired dimensions, and then simply cutting to the appropriate depth for your 2D QRD/PRD? what type of mfg's usually carry EPS - so that i can begin calling around?

thank you,
Old 11th August 2011
  #29
Here for the gear
 

Where to get EPS

I've been using Owens Corning F-250 in 1" and 1.5" thickness. My local Home Depot carries both in 2'x8' strips. Ive been doing the cuts manually with a straight edge and extra long safety blade. Making each 2'x2' panel takes me 4-5 hours. Here's a pic of two I have completed:



I'm thinking that a coat of resin or something else hard and dense would be more effective than just painting with latex, but given that the frequency cutoffs for these are 1100 hz and 848 hz, latex may be sufficient.
Old 11th August 2011
  #30
Lives for gear
 

Quote:
Originally Posted by localhost127 View Post
Jens will likely chime in - but he has measured differences between painted and un-painted. the painted seemed to be much more reflective (which improved the diff/scattering coefficients, if i recall correctely (didnt bookmark the post)) - but let him confirm.
disregard that - this is the very thread. see post 5:
https://www.gearslutz.com/board/6732069-post5.html
Post Reply

Welcome to the Gearslutz Pro Audio Community!

Registration benefits include:
  • The ability to reply to and create new discussions
  • Access to members-only giveaways & competitions
  • Interact with VIP industry experts in our guest Q&As
  • Access to members-only sub forum discussions
  • Access to members-only Chat Room
  • Get INSTANT ACCESS to the world's best private pro audio Classifieds for only USD $20/year
  • Promote your eBay auctions and Reverb.com listings for free
  • Remove this message!
You need an account to post a reply. Create a username and password below and an account will be created and your post entered.


 
 
Slide to join now Processing…
Thread Tools
Search this Thread
Search this Thread:

Advanced Search
Forum Jump
Forum Jump