# Polystyrene Diffuser



## puneet_dh (Feb 6, 2009)

Dear HTS members,

Apart from rock wool panels, I have some blank wall on top of panel and a blank back wall . I am planning to add some diffusion using 1D QRD diffusor and looking to use Polystyrene as material.I would finish the diffuser with plastic paint.Can you suggest if this would be a good choice? I want to avoid wood due to budget issues.

Thanks,
Puneet


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## bpape (Sep 14, 2006)

It can work somewhat as long as the material doesn't have any absorptive properties. A high density packing type styrofoam can be carved to do OK in the upper mids and highs, though won't be rigid enough to do much in the dialog range and down.

Bryan


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## puneet_dh (Feb 6, 2009)

Bryan,

Other option I am considering is to stick thin 1/4 inch wood strips in the wells but fins would still be of Polystyrene.I'll put two layer of primer before 2 quote of paint. Ofcourse I am assuming that surface of a diffuser should be hard (1/4 inch wood strips are hard) and what lies behind should not matter for frequency range 750 and above.
Please correct me if I am just imagining too much 

Puneet
P.s I am using QRDDUDE software


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## bpape (Sep 14, 2006)

Certainly won't hurt anything. I'd think the fins in that type of setup would be the most likely to have some vibrational issues though.

Bryan


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## puneet_dh (Feb 6, 2009)

Thanks Bryan.
I am sharing some of my room picture and location where I intend to put diffusers.
Room is 12.8 Feet wide and 18.1 Feet Long and 7.6 Feet high till roof ceiling.Distance between seat and wall is more then 6 feet.We generally move our couch to make two rows before watching movies otherwise they are placed adjacent to side walls.
Front wall has a 12 feet long window but totally (Top to bottom) covered with 7 rock wool panels hung using French cleats and a thick curtain.Rockwool panels on side wall are 2inch thick with 50 Kg density.


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## bpape (Sep 14, 2006)

Looks good to me - though I might consider a nice thick bass absorber on the rear wall instead of diffusion to help with nulls off the back and tame the nook a bit. A lot of the diffused sound is just going to bounce into those alcove walls.

Bryan


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## puneet_dh (Feb 6, 2009)

Bryan,
When I test my surround right channel individually using receivers test tone, I hear two sounds one coming from dipole and other being reflected straight from back wall, hence I though of putting diffuser.
I am not very satisfied with the surround field that is being produced right now.i was hoping to make it more immersible but front speaker sound stage is quite predominant.This is even after using Audyssey. 
Looking at pics, can you suggest any thing else that might make things better from acoustics point of view
Thanks for your suggestions.


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## bpape (Sep 14, 2006)

My guess on the surround issue is how close together the rear channels are. I know it's a very limited space but you could try to pull them a bit farther apart as long as you can keep the baffle of the left rear in front of that little wall that bumps out. The right rear will get very close to the boundary so that side would need to be deadened.

Bryan


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