Looking for reasonably priced sound diffusion.

i just noticed this thread. recently i did install Auralex T-Fusors on my side walls. two years ago i installed RPG Skylines on my backwall. here are some posts from my system page which might be helpful on this subject;

i realize i likely need diffusion on the side walls and decide to try the T-Fusors;

decision

installation and my first impressions;

impressions

pictures unpainted;

unpainted

pictures painted;

painted

FrankC (Gundam91):

Just wanted to clarify one of your points above - taken from the RPG website: "H The overall dimensions shall be 23-3/8"(H) x 23-3/8"(W) x 7"(D) and weigh no more than 4 pounds." found at this link http://www.rpginc.com/products/skyline/sky_csi.htm

So, the Skyline depth is 7" and not 2". Physics as they are, it's the max depth of the Skyline cell that determines its lower freq limit that its diffusion works to, while the inter-cell pressure which is a function of the cell size determines the max high freq limit. Dr Floyd Toole's latest book has an entire chapter on this and other diffuser types and absorption products . . . definately worth the read.

I took a closer look at the mio tiles. And I have some ideas of how to improve it:
1/ it's not paper thin. From the spec, it looks like it has the thickness of a paperboard. Someone mentioned about depth. But if you look at the RPG skyline, they are all about 2 inches deep.

2/ the surface is paintable. I would suggest to paint it with spray paint or spray on some water-proof stuff on both sides if you are worrying about it "sagging". I would think you have to like pull lots of water directly onto it for that to happen. Check art stores for the type of stuff they use, rather than the ones from Home Depot or OSH.

3/ maybe stuff inside the pocket with some foams. Maybe randomly, or with various sizes. I've been collecting this stuff to pack up my house for remodel. I'll use them afterwards.

If they show different colors, they should offer various colors as well. Bummer.

FrankC

I made a 2' x 4' panel from the MIO diffusion tiles to attach to the front of the large flat screen TV in front of me and between the speakers (my living room doubles for my HT and stereo room). I did this to try and counteract the sound reflections coming from such a large flat surface in front of me. The perception is that sound became more defined, spacious and less 'glary'.

i'm curious if absorption in front of the TV would work better.

Kevinzoe

Thanks so much for all of the information.

Very nice of you and you seem quite knowledgeable.

Grannyring,
I've done quite a lot of diffusion studying, communicating with Prof Trevor Cox and Dr Sean Olive, and built several DIY Skylines and Hemi-Cylindrical diffusers, so I hope my words of wisdom will be considered by you.

CAUTION: www.mioculture.com/store/pc/vi... This stuff is recycled paper, is only 2.25" deep, and its installation instructions say it will warp with humidity. RED FLAG, RED FLAG, RED FLAG. Paper is too thin to be considered a diffuser, except for the highest of frequencies (which is great if you're a bat). It's depth needs to be a miminum of 8" so 2.25" is clearly inadequate. So, I'd recommend you pass on it. (I guess you get what you pay for in this instance.)

Why do you want diffusion (or anything) on the ceiling? Is it to raise the apparent ceiling height? I can tell you from 1st hand experience that the RPG Skylines on my 7ft ceiling had little effect on raising the apparent stage height. Dissapointed - yes, a bit, but it could be due to any number of things like my speaker's vertical off-axis response being poor, too sharp an angle to 1st reflection point based on sitting distance from speakers etc etc.

Have you considered using say 2"*6" or larger planks of wood and angling them? Start with the 2" part touching your ceiling and hanging down perpendicular to the ceiling and running across the room width of your ceiling to cover the left and right 1st reflection points. Then begin to move the bottom of the wood up and towards your speakers; any sound hitting the ceiling will become trapped inside the area bound by the ceiling and plank and will bounce around before coming out delayed and attenuated. Hang several of these and you can elect to put some fabric over them and put fibreglass inside the fabric to partially absorb some of the sound.

Another effective and yet reasonably priced product is GIK's D1 diffuser which follows a modified QRD pattern. Hang them so the well orientation aligns with the room's length so sound hitting it will be diffused to the sides.

You will want diffusion that latterally affects the sound so QRD (with wells oriented vertically) or hemi-diffusers (convex and length oriented vertically) should do the trick. Latteral sounds help envelop the listener and widen the sound source, both positive traits.

With any diffusion product, it is the depth of the QRD wells, Skyline cells, or hemi-cylindrical radius that determines the low frequency that it will effectively work to. You want one that will work down to 300Hz (which is a good estimate for a residential room's Schroeder/transition frequency) for which Dr Floyd Toole recommends a minimum of an 8" depth for QRD and Skyines and 12" depth for hemi-diffusers. The material needs to be firm enough - no paper products please - to be effective at diffusing high and medium frequencies.

PLACEMENT: I would suggest that you put diffusion on the wall behind your listening chair before you try the front wall. Firstly, you're sitting closer to the back wall so it's effects should be more pronounced and will help deal with many 1st reflection paths from the speakers. Secondly, unless your speakers have rear-firing tweeters that're turned on, the front wall is likely the least important because sound has hit several surfaces before making its way to the front and each surface 'hit' attenuates it, and the sound signal experiences propogation loss (6dB down per doubling of distance). My experience with absorption on the front wall - I'm excluding bass traps in the corners now - is that the absorption will deepen the sound stage while diffusion will bring it forward, clearly a personal preference thing.

I would suggest that you also take down the side wall absorption - especially if it's thinner than 4" - and listen with just the bare wall as Toole's studies have shown the side wall reflections to be GOOD things in widening the apparent sound source when enjoying music. He saying that side wall 1st reflection points should be absorbed when you're mixing music or evaluating listening components.

In my room I had a wicked slap echo between the side walls so my hemi-diffuser (i)killed the spap echos, (ii)had a hard exterior (i.e.red oak veneer) so that medium/high frequencies weren't absorbed and (iii) used OC 701 fibreglass inside it for addional bass trapping. I experimented with moving the hemi-diffuser along the side wall and found the best sound came when the 1st reflection point on a side wall from the closest speaker was left bare (i.e. reflective) while the reflection point from the speaker across the room was diffused. This seems to align with Toole's research that says the most significant side wall reflection comes from 60degrees (looking straight ahead = 0degrees and over your shoulder would be 90degrees). You can use trigonometry to figure out where the 60degree point is and mark it - it may be very close to the 1st reflection point of the closest speaker when you use the mirror tecnique.

ASC cool traps are new and what I used. I can't remember the price but that come in quanities of 16 and are 1 foot square. It seems to me they were like $300 or so for 16 but I could be terribly wrong. They look good though when placed together in rows and do the trick for sure. They can be used in a variety of ways, not just ceiling. I have some left over and have yet to figure out where to go with them.

Wow, some great stuff here. Thanks to all for taking the time to post. I am most interested in those acoustic tiles on the website

www.mioculture.com/store/pc/vi...

Blindjim, do you use these? Has anyone tried these? Goodness they are easy to put up, attractive and cheap!!! These may be one heck of a find. Just wonder if they are effective. This could be an answer to diffusion for all of us Aphiles on a budget. They look great also!

Blindjim asks some very good questions and I don't have the answers to be frank. Hope others can share from experience .

I’ve a couple Q’s here myself, please. … and maybe an answer as well for the OP…. or at least an alternative choice

First… How low a ceiling does one have to have for these things to be of consequence? Or is there some specified distance from the top of the speaker to the ceiling in order for these gizmos to be effective?

Next… Why would actual diffuser panels or squares be better and how does one decide how much and where to place it/them?

When I repainted and remodeled the living room for a theater, I wrongly listened to others and had the ceiling painted a similar but softer white. Bad move. The eye catches enough of it to be distracting as the screen is wall mounted, so it needs to be much darker.

I vaguely recall a wall paper maker that has a fairly good selection of fabrics and colors that act as diffusion and very slight absorption. Materials and are assigned the terms ‘Acoustical room treatment fabrics’.

The idea of diffusion on the ceiling and changing the color as well seem a good enough reason to put the difuse wall paper up there in my circumstance. As it won’t catch the eye like individual panels will, and should prove quite complimentary without over damping a room.

It can be had in tiles or rolls depending on who you get what from. In one case I noted 12 tiles sell for $35.

http://www.mioculture.com/store/pc/viewCategories.asp?idCategory=2

www.noiseout.com

http://designerwallcoverings.com/WallpaperStore/index.php?main_page=index&cPath=590

other’s are out there for sure… just keep Googling.

also Decware has a kit which i think would be right in your price range and would take a shorter time to build. the kit for 1 pair 24 x 24 x 3" Diffuser kit P1324 goes for 150.00 and are made of solid wood and most likely glued together using carpenters glue...

Sorry for beating this to death, but I found the original site that I wanted to mention. mh-audio.nl ,acoustic calculators galore for DIY. Go to the online calculator section, not the download section. You will find all the info that you need to desigh, have fun!

I forgot to ad that pmerecords.com also has plan for a DIY Skyline QRD and a link to a calculator for specific freq designs. The calcultor is part of a larger site that also has calculators to design all the different diffuser styles.

Go over to subwoofer-builder.com . They have an extensive article on DIY QRD and Skyline style diffusors. The Skyline styles are quite easy to DIY and will cost far less than your target price of $80 each.

Hi Bill here's what I did with my ceiling. Had an insulation contractor spray cellulose insulation about 1" thick: did the entire room ceiling + about 6" down the sidewalls from the top. This is the same process used to insulate industrial buildings, warehouses etc. The applicator nozel mixes a liquid latex adhesive with the fiber coming from the hopper via a high-RPM blower. The cellulose is highly pourous and randomly surfaced which is a highly effective solution for slap echo. The room remains slightly on the 'live' side which is exactly what I wanted. It didn't cost a lot either.
I had them use bleached white cellulose vs. the typical gray color found in warehouses. Dye can be mixed with the adhesive for other colors if desired. You have to cover or remove furnishings, and mask the walls and floor with plastic sheet and tape because the stuff sticks wherever it lands. Although if you want to have some corners or backwall areas covered, to whatever thicness desired, it is easily done while the crew is onsite.
I actually had my whole house done, not just the living-listening room area. It adds some R-value as a side benefit, and quiets the whole house too. Of couse your attic insulation can be agumented as well; this does not require the adhesive, they just blow it down to whetever specified thickness. And gray works there or even in the basement / crawl space too.

Auralex makes a 36 panel pack for 99.00 there 12"X12"Squares there light and look very easy to mount. You could consider them and if you like what you hear you can always move up to a more advanced model diffuser.