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Constructing 2D QRD Diffusors

Brandon Drury —  June 4, 2011 — Leave a comment

QRD 2D Diffusors
Here’s a pic of my back wall at the moment. Ignore the Roxul wrapped in fabric at the top. That’s just temporary until I can build the next set of diffusors.

I made a multitude of mistakes when constructing my diffusors so hopefully this section will help you not repeat my faults. I’m NOT a construction dude. I’m a wanna be guy. I’m like those wanna be recorders still using the stock soundcard in their laptop. On most days I’m clueless but every once in a while I pull something interesting out of my ass.

QRD Dude told me the exact number of linear feet of 2x2s (actually 1.5” x 1.5”….don’t get me started on that rant) so I bought a few extra. For what I had in mind I needed 53 2x2x8s which cost me about $100, give or take.

Wood Dry Out

The wood at Lowes wasn’t exactly A-grade wood (which is okay with me) and some of it was pretty soaked. One piece may weigh double what another piece weighed. The first step was to let it dry.
Wood Drying

Sanding

Then the sanding began. I initially used a 180 weight sandpaper, but that was way too fine for what I’m up to. This isn’t neurosurgery woodworking. It’s more blunt-force woodworking and I found a 60 weight to be much better for smoothing out all the rough stuff and the final results are fine. (Actually, as we’ll get to, other factors got in the way of these things looking as good as I wanted them to.) If a person wanted to go full-blown death on this sanding business and make each piece of wood perfect, I’d guess you’d finish this project about when my grandkids die or when India loses it’s status as the world superpower.

Sanding
Note: Notice my unique lawn mowing pattern to confuse the cops. This is my first year of not getting a formal warning for not taking care of my yard.

Staining

Staining

Bitches

Jasmine, the bitch from up the street, decided to inspect my work up close while attempting a breaking an entering to my home. One benefit of being 31 is you start to find dogs trashing your work humorous. When I was 25 I would have pulled out my .45 ACP and removed the hostile.

Damn Dog

Polyurethane

Here’s my setup for applying the polyurethane. I’d do one side of about a dozen boards, come back 45 minutes later, rotate them 90 degrees, and repeat. I wouldn’t listen to me on this one as I had all sorts of runs. My technique improved by the end where I was more careful to distribute the polyurethane evenly on the first swipe.

Polyurethane

I tried out some new “hippie” paint thinner. It was a buck cheaper and preached all the green environmental crap. When I opened it, it looked like watered-down milk. I wasn’t pleased, but the stuff ended up being pretty good. The milky stuff disappeared when I do my polyurethane work. I did find some good ol’ destroy-the-Earth mineral spirits that I used for final clean up just to make sure the brush was totally clean, but overall I’m pleased with this hippie paint thinner.

Big Problem: Circular Saw Support System

I had just read in a woodworking book about creating a guide support thingy for a circular saw to make it possible to cut very straight lines. I thought this was awesome. I made one and it worked well for some other things I was up to. In this particular case, the 2×4 was too tall so I made a quick decision to shorten it and turn it around so that the motor of the ciruclar saw didn’t hit the guide.

Saw bracing

The one thing I didn’t think about was the angle in which the cut would be from one axis. It didn’t occur to me that the super-short nature of this guide wouldn’t give much support on the other axis. This is tough to explain via text so I’ll let the picture do 1,000 words.

The end result, which I underestimated the severity of at the time, was it looked like my 2×2 pegs had been through a hurricane. They were bent or sloped. This meant assembly of the first diffusor took FOREVVVVVVVVVVVVVVVVER because the blocks could only be orientated one way.

Gap in diffusors

You can see this clearly here. This gap was caused by the larger 8 15/16” 2x2s with the bad angle mentioned above. I really thought that the ability of the circular saw to cut 12 pegs at a time would be the most efficient. Back to the drawing board.

Big Problem: Polyurethane And Stain Before Cutting

I figured it would be more efficient to stain and polyurethane 8′ long 2x2s than try to stain and polyurethane 3” long 2x2s That’s common sense. What I didn’t factor was the splinter factor from sawing.

Split wood

This immediately made me realize that I had made a mistake by doing the finish work first. A part of me thinks that some kind of spray-paint solution of a color may not be perfect (and may be tough to get right in deep in the wells) but it has to be a better solution than this. The best approach, as many have done around the web, is no finish at all. Natural wood looks pretty cool and would save you a TON of time and headaches.

I thought I was doing something totally wrong that was causing these wretched splinters. I did some quick research and found out that all saws are going to cause splinters on a crosscut. It’s just an issue of where and how much. Going slow is a huge help in reducing them. The angle you hit the wood with the saw is another. It turns out that I was hitting the wood at a terrible angle with the circular saw, which was cranked to it’s 2.5” max to make it through the guide and the 2x2s. Not good. This bit me in the ass later on.

Miter Saw

Miter Saw

I ended up going with the miter saw. The miter saw always cuts straight at no angle (unless I want it to). This totally solved the angle issue and ultimately made the assembly stage of the next two diffusors exponentially faster. Don’t let the picture confuse you. I was only able to cut 4 boards simultaneously with the miter saw, which did increase cutting time quite a bit compared to the 12 simultaneous boards I was getting with the circular saw.

Miter Splinters

Here’s a good example of what the best and worst cuts of the miter saw looked like. The left is the top cut in the ideal position and the right is the bottom cut in the least ideal position. The bottom of the left piece doesn’t look much better, however. In the end I just rubbed off the splinters with my hand. Ironically, I went through close to 450 pieces of wood and none of the splinters stuck to me. On the first batch I used sand paper, but I wasn’t any more impressed with the results.

I want to point out that these saws are NOISY. That’s kind of a given. I always wear ear plugs with this stuff. I saw something somewhere that 90% of your hearing loss is caused by the loudest 10%. Just knocking the edge off the crazy loud stuff can be a huge deal.

My hearing is easy to protect. I have to say that I started to feel guilty for making hundreds of cuts. My neighbors were extremely patient and never complained, but I felt like an asshole by the end of the marathon of cutting. If you are in the kind of neighborhood where running a saw for hours at a time is frowned upon, you may want to consider other options. I get the feeling that there is some woodshop somewhere that can push 3 buttons and in 5 minutes 600 pieces of perfectly cut wood pop out. Maybe not.

Panzer

Panzer The Dog

Panzer decided to sleep exactly where he’d get covered in dust from the miter saw. He’s not the sharpest dog in the drawer!

Cat
When I told the ol’ lady that I wanted a lot of pussy, this wasn’t what I had in mind.

Note: Weak attempt at humor over. SMILEY

Diffusor Grid

My 2D QRD diffusor called for 12 different peg sizes that started at 3/4” and progressed up to 8 15/16” . I kept them organized by placing them in plastic Walmart bags. I made sure to toss a sheet of paper with their length number (1-12). This came in handy quite a bit as it’s easy to mistake the different sizes when assembling. Best of all, it made little “compartments” on the couch that made it easy to grab the size I needed. I considered buying little tubs for this, but the Walmart solution was totally adequate.

Diffusor Grid

Here’s the 19.5” by 19.5” foundation. I used 5mm thick plywood. It served the purpose just fine. This grid was entirely necessary to ensure that the pieces went in correctly. I would have been totally screwed without it, although for some reason I really hated drawing those lines. Not sure why.

Diffusor Assembly

Table Saw Assembly

Here’s the first day of assembly using the pegs from the circular saw. It’s easy to see how none of them line up right and the general worksmanship is somewhere between panty waste and dog shit.

Diffusor Assembly
One day two of assembly, using the miter saw cuts, productivity was infinitely better and the worksmanship is better. Not good, but better. I decided to live with the rubbed off splinters. Time was running out. You can see the MaxData function on the laptop from QRDude, which made it easy to keep track of where I was in the assembly process.

I found that by assembling two indentical diffusors at the same time I was able to save a ton of time. If you take a look, you’ll notice that each half row (left to right in this pic) is symmetrical. So every time I needed a size of peg, I simply grabbed four from the bag, one for the left and one for the right of each diffusor.

Wood Glue
Yes, perverts, I’m SURE that is wood glue. On day #1 I glued each piece individually. I kind of had to. I also glued each side of each peg to the other pegs. I had read previously that the additional glue connecting the pegs wasn’t necessary, but they didn’t qualify it any further. My 12 piece (the longest piece) is 8 15/16”. On day #2 I decided not to glue any of the pieces together. I wanted to see if it was necessary to use any glue other than sticking the pegs to the foundation.

When I had to move the diffusor from day #1, when I picked it up it felt like I had picked up a cinder block in terms of structural integrity. It felt like one piece with not a hint of flex. Solid is a good word for it. When I had to move the difffusors from day #2, there was some flex. It was quite acceptable, but it wasn’t rock hard. It felt strong enough, but my confidence level was lower on this one. Who knows what it will be like in a decade. Wood glue is cheap. So I don’t see any reason not to glue the tall pegs together, which is what I did for the last diffusor.

For what it’s worth, when a healthy amount of glue is added, these things are STRONG. In fact, I had an overhang from one of the 3/4” pegs that I somehow goofed. I noticed it about 3 hours after I had glued it. I used both hands to attempt to shake the hell out of the damn thing to pull it off. I gave up. I suspect that with a flathead screwdriver I would have torn the wood foundation before the glue gave. Since there is no significant leverage working on the little pegs, I don’t see any need to reinforce them.

You’ll notice in this pic that I had all the pegs for the next go around ready. I’d slap on glue for all the squares that needed it (some squares are empty) and quickly put the pieces I place. This was a very efficient way of working. You can’t screw around with this method, but I didn’t feel I had to rush. While I didn’t officially time it, I want to say it took about an hour and 10 minutes to assemble both of these diffusors. By far, prepping the pegs took dramatically more time.

If a person could find some lightweight material that could be ordered to be the correct size and finish, they could save a ton of time and headache.

Was It Worth It?

I DID NOT expect the work load to be THIS high. It was a TON of work. Each step makes via the pics makes it look like a wham bam thank you mam kind of operation. Each one of those steps took quite a bit of time. It was amazing how fast each hour flew by. I started on Tuesday and put in long hours to get them finished by Saturday.

If you have more money than time, just buy some pro diffusors. Gik and Realtraps make great stuff. Tell Glenn or Ethan I sent you.

If you have free time and like building stuff, knock yourself out. You will feel like someone beat the shit out of you. At least I do.

It’s too early to speculate how they sound. Coming Soon.

2D QRD Diffusor

Saved Comments

26 Comments

mgraham70 – 06-29-2011, 03:00 PM Edit Reply
Thank you for sharing the experience. I have fairly significant wood working experience, under my belt (yeah, that too, you perv!) and a woodshop… so I had intended on building a couple of these (thanks to Tape Op). I’m looking forward to how they work out for you and if they end up being worth while. Thanks, Brandon.

drgamble – 06-29-2011, 03:09 PM Edit Reply
I have seen these type of homemade diffusers in studios around here and they seem to do the trick. How many panels did you build? If I remember right, the studio I am talking about has these on 3 walls and the ceiling. I believe the one on the ceiling is larger, maybe 4′x5′? There are all positioned perpendicular to his mixing spot. What is amazing is that the room is very consistent. There is not a huge difference between the sound sitting in the sweet spot and anywhere else in the room. It is also remarkable that the mix you hear in his control room is very close to the sound you would hear on any stereo, at least the ones I have tried it on. I think you will be happy with them and I hope they make the improvement that you are looking for.

brandondrury – 06-30-2011, 01:24 PM Edit Reply
I have fairly significant wood working experience, under my belt (yeah, that too, you perv!) and a woodsho
I hate you! I’m jealous. While I’m a TOTAL beginner in wood land, I’d LOOOOOVE to have my own woodshop. Some day!
so I had intended on building a couple of these (thanks to Tape Op).
I have another article coming up for the design of my diffusors. I did not use the Tape Op design. The Tape Op design is a heavily quantized PRD diffusor that only diffuses down to the 1k range (if I’m remembering correctly). That’s not to say that they don’t do a great job for that, but they won’t have any impact on the low mids, which are something I definitely wanted diffused in my room. So my design is quite a bit deeper. The deepest “peg” was 8 9/16″. So keep that in mind.
How many panels did you build?
I built 4 so far. It looks like I’ll have to check my Barker Codes and add another one since the design of the stands (above the bass traps) allows me to fit one more. From there I’m debating if I want to dedicate 2-3 more days making more 2D diffusors or just fill the rest of the wall with 1D diffusors. I’m leaning in the 1D direction at the moment, but I’ve got a mixing project I need to finish before I start another mammoth undertaking.—-Sound UpdateI had a session Tuesday and I mixed a song Wednesday. The low end is quite a bit “less murky”. The kicks hit harder without all the flab. It’s a noticeable difference. I would have noticed in a blind test. No doubt about it. I’m also hearing quite a bit less “cloudiness” in the room. While the room doesn’t really sound more live to my ears (at least not yet, this is only about 1/5 the diffusion I plan on doing in the room) it does sound like a lot of low mid crappiness has been neutralized. I can’t wait to hear what this sounds like when I get it finished.

mgraham70 – 07-01-2011, 03:01 PM Edit Reply
Originally Posted by brandondrury
I hate you! I’m jealous. While I’m a TOTAL beginner in wood land, I’d LOOOOOVE to have my own woodshop. Some day!I have another article coming up for the design of my diffusors.

Don’t be hatin’… there is plenty of jealousy to go around. I’m extremely jealous that you’ve been able to make engineering/production your day job. I spend most of my work day, thinking about how much I’d rather be in my studio. With that said, I’m not really complaining. I’m very lucky to even have a studio (and a woodshop).

The woodshop came about, believe is or not, because I’m a frugal bastard. I own and run an independent record store (yes, vinyl and CD). I’ve been doing it long enough that, rather than leasing, I purchased my building in 1999. Something you have to understand about me, I hate paying people for doing things that I can do for myself. I built my woodshop into my budget for two reasons. First, there always maintenance to be done, when you own a building. Second, my store is actually rather large (at least for my city). To purchase display tables that are “made for” records and CD display are extremely expensive. In all honestly, I knew that I could build sturdier tables and racks, for a fraction of the price… if I had the tools to do it. So, over the years, my shop has paid for itself.

Same with my studio. I got tired of paying other people to do a half-assed job recording my bands (over the years… yes, I’ve spent quite a bit of time behind these other’s mixers though, no formal training). I’m not claiming that everyone who owns a studio does half-assed work. What I do feel is that I can do an as good (maybe better) job than the studios in my area. There is too much travel time and expense involved, for me to get the quality that I’m looking for… and aspiring to.

I’ll be looking forward to your next article on your diffusors. What I’m wrestling with, now, is a design that suits my specific control room. I built my studio, from my own research & design, to actually be a studio. So, I do not have any square (or rectangle) rooms. My control room has many angles (though it is symmetrical). Even when my room is totally empty, with no treatments, there is no perceptible flutter echo. Which I thought was pretty cool (at first) but, most of the research that I’ve seen, on traps and diffusion, talks about formulas pertaining to rooms with right angles…. measuring distances between walls. I guess I kinda angled myself in an acute corner (ok, well I thought it was funny )

Having said all this, I do think my room sounds pretty good but, I’m trying to tighten things up a bit and get a larger sweet spot.

As always, I appreciate your perspectives and insight on these studio matters. I’ll be watching for your next article. Thanks, Brandon.

IMF OnSite Recording – 07-04-2011, 10:19 PM Edit Reply
I assume these are for absorbing 7-800hz and up?

alexmcginness – 07-05-2011, 11:45 AM Edit Reply
why not buy a single diffusor from the big boy Ethan and reverse engineer it and build a bunch of duplicates? Why re invent the wheel or try to “guess” as to how they should be built?

Sir Les – 07-05-2011, 12:42 PM Edit Reply
….Why not invest in heavy duty Elevator/construction/demolition curtains?..put em on ceilling tracks..and fold and unfold as needed?…Easy to install and uninstall….I think they would remove reflections very well, if accordian folds or pleets were made, that might even improve on reflections…Just a thought….Not sure about wood Pricing and glue and tools and time…but it wouldn’t seem as labour intensive as to what you are doing here…less mess to clean up to…and lets not forget washing the dog…all that is time…time is money…etc….again Just My thoughts…

brandondrury – 07-05-2011, 02:48 PM Edit Reply
I assume these are for absorbing 7-800hz and up?
No absorption…at least no practical absorption worth mentioning. Head to Home Studio Diffusion 201: What You Need To Know and scroll down to a new section I just added called “My First Design”.
why not buy a single diffusor from the big boy Ethan and reverse engineer it and build a bunch of duplicates? Why re invent the wheel or try to “guess” as to how they should be built?
This is a fair question. I guess the short answer is about $10,000 for the number of diffusors I need for both my control room and live room. While I did do some guessing, I feel that I’m in safe territory on this one. I would prefer absolute certainty, but I can’t think of any situation in life where you get that from day one. A major part of this gig is being the guinea pig who’s going to tell you how it is. It was important for me to know if DIY diffusion was worth it, how much work it required, and what difference it made. I know of no such resource yet. I’m not positive the Realtraps would be any better or worse. That’s a test for another day.
Why not invest in heavy duty Elevator/construction/demolition curtains?..put em on ceilling tracks..and fold and unfold as needed?…Easy to install and uninstall….I think they would remove reflections very well, if accordian folds or pleets were made, that might even improve on reflections…Just a thought
Not a terrible idea, but that’s not diffusion. Check out the “Schroeder Diffusors Are What I Want” in Studio Diffusion 201: What You Need To KnowThe math has to be dead on for the magical state of diffusion to exist.
time is money…etc.
DEFINITELY!! The last one took 3.5 hours (not counting finishing, which I’m not doing anymore anyway). The Realtraps diffusors go for about $600. Gik makes them for quite a bit less. The Realtraps do have bass traps in them, which is pretty cool, but this felt like the right way to go for the reasons stated above.I think I’m going to hire a handyman to do all the sawing on the next venture.While lots of work, you have to remember that I’m on a computer 18 hours a day 360 days a year. Getting the tools out, getting a workout, and getting a tan is a vacation for me.

metaphorman – 07-05-2011, 04:01 PM Edit Reply
I have been sorely tempted to build my own QRD diffusers…. found the plans and some software and such. Bought a styrofoam cutter.

Then I had to move, so I haven’t started the venture yet. I am kind of antsy around power tools, so I found another approach. My half-assed idea was to use the styrofoam 2 inch blue sheets from lowes and cut them with a styrofoam cutter (hot wire) into the shapes for QRD’s….. basically cut out some comb shapes already attached together and glue the two foot wide “combs” together with GreenGlue… then spray on the front and maybe on the back some eDead goo or some other noise suppressant like the QuietCoat stuff found on the ATSacoustics website in order to knock out those styrofoam resonances, and stick velcro on the back of them to allow me to hang them on walls and gobos and hanging off my portable closet racks. Make a whole wall or two out of that, and tune it for 500 hz (?), and stack a bunch of rockboard or something comparable in a 2 foot deep stack from floor to ceiling behind it.

Cheaper and less labor intensive than wood. Weighs less to.

I like the idea of experimenting with velcroing them to my ceiling, which has horrible comb filter problems when I stand up to do vocals in my studio. Not sure what the effect of having 7.5 foot high ceilings with long probes hanging down so close to mic is going to do though. Might just use more 4 inch auralex foam that I seem to have everywhere after I snagged a whole studio full at 75% off. Anybody tried anything like that?

I wonder what it would look like to have a whole wall covered with dried crusty eDead goo… it comes in dark grey and blue. Spray paint looks tacky… cover it with cloth, maybe? The wood looks pretty cool, though. I gotta admit.

At the moment I have 10 of those auralex T’Fusors. Not sure what to make of them. Tried using them during recording sessions, and everything sounded like it was being recorded in a plastic bowl. Hated it. Several hundred dollars down the drain? Walked up to them talking with a ribbon mike in hand and came to the conclusion that they had a severe resonance signature, even when loaded with foam and/or polyester batting the way auralex tells you to prep them. Painted the insides of them with eDead (kind of like a paint on version of dynamat used to silence car stereo resonances inside car doors) which seems to not make them sound like the same anymore, right before moving and disassembling my studio so I have no idea what they are going to do to recordings now. Anybody worked with those beasties?

alexmcginness – 07-05-2011, 10:01 PM Edit Reply
a difusor and bass trap to support it is only around $750 not ten grand from ethan. Buy one and build duplicates!

SuprchrgedSi – 07-06-2011, 12:18 AM Edit Reply
Ok I have a question as to mounting multiple diffusors. Do they have to be right next to each other, or can they be spread out across a wall in a checkerboard shape. I would think that this would still provide the capability of “livening up a room, but not require quite as much material when all is said and done. Was there anythign in your reading about this Brandon?-Jimmy

mgraham70 – 07-06-2011, 07:34 AM Edit Reply
Originally Posted by SuprchrgedSi
Ok I have a question as to mounting multiple diffusors. Do they have to be right next to each other, or can they be spread out across a wall in a checkerboard shape.
Diffusion is way more complicated than that. There isn’t really a “one size fits all” way to deal with proper diffusion. I suggest that you read (if you haven’t already) all of Brandon’s recent articles on his quest for diffusion (found on the HOME PAGE). There are three articles, starting with “Diffusion: At What Point Should You OBSESS Over Acoustic Treatment?”. Tackling diffusion is not for the timid. There are ways to identify specific room issues and formulas for dealing with the issues. I knew that diffusion was tricky but, Brandon’s articles have really shed some light on how deep, the topic of diffusion, really is.

Traps are significantly easier to deal with (easy “er”… not necessarily “easy”). My opinion is (and I’m no expert) make sure that your room is under control, with proper traps, first. Then dive into diffusion, “if” you still have the will for it (especially if you’re a “do it yourselfer”). I’m walking that line right now. I’ve gotten my rooms under control but, now, I’m looking to tighten things up with diffusion. Brandon’s experiments and articles have been very helpful in showing how deep those waters really are, before you dive in.

SuprchrgedSi – 07-06-2011, 09:07 AM Edit Reply
Awesome mgraham. Thanks for the advice. I’ve already built 13 panel traps/absorbers, so the next step was to move on to diffusion to help liven up the room. It’s both my studio and my live room, so there’s a need for both in here. I’ll definitely go back and look more thoroughly into it.-Jimmy

IMF OnSite Recording – 07-10-2011, 01:21 PM Edit Reply
I was thinking of doing 23 1″ wells seeing that the cutoff is considerable higher (6880hz). Labor looks much more complex though. Let’s say you could make ANY spec in 5 minutes, would you have gone with 23 1″ wells as opposed to 13 1.5″ wells? Just curious. Also, a rough texture will diffuse even higher frequencies (like that of asphalt or a brick). Do you think spraying these diffusers with, say, truck bed liner or something rough textures would improve that?

DanTheMan – 07-15-2011, 10:57 AM Edit Reply
Thank again for doing this! FWIW, the poly will kill the wood glue’s ability to stick anyway so gluing in between won’t be of any real benefit. It will stick a bit, but not more.
Instead of more ‘live’, I’ve actually found that adding diffusion make the room sound more ‘dead’ in a sense. It almost sounds like the walls are not there, but certainly not like you are in an open field. The energy is still there, but it’s just more spread out and less direct in time and direction. It’s really hard for me to describe, but I definitely like the effect and it seems to clarify most everything I play in there and I don’t have good diffusion at all. It’s just the cheap Auralex T’Fusor. They took away all my flutter echo, but many people state they are no where near as good as a QRD and I bet they are absolutely correct. Just look at the T’s simplicity. But it was cheap and fast. Still, I want to add some better diffusers when time/money permit.You can look here for some performance data:Auralex Acoustics – Acoustic Product Performance Data

the Q’Fusor: http://www.auralex.com/sec9/Specifications_QFusor.pdf

GIK is essentially crushing them with the D1: GIK Acoustics. Acoustic Panels and Bass Traps.

samuelfi13 – 07-19-2011, 06:48 PM Edit Reply
Brandon,

Thanks for ALL of your articles on the subject of room treatments — I’ve found them VERY educational and helpful. The links to free software and other web pages have been great too. You put a lot time and effort into everything you do on this website and I feel that all of us who visit here are the better for it. I can’t thank you enough.

While my musical tastes (and recording experiences) are more acoustic than electric, I’ve still learned a lot from you and the other readers/contributors here. Even though I’m probably twice the age of most of you, it just goes to show you that one is never too old to learn something new…. In the last six months I’ve also come to appreciate the joys of the Grateful Dead and their spin-off bands. (I was a Jefferson Airplane, Who, and The Doors fan long before I learned to appreciate the ‘Dead.) Drivin’ down the highway, listening to live ‘Dead…well, at my age, life don’t get much better than that….

Last, but not least, I want to thank all of you other guys who take the time to share your questions, insights and experiences on all the articles and forums here. You broaden the perspective on things and also contribute a lot of useful info to the mix. Thanks a bunch.

garageband – 07-19-2011, 08:50 PM Edit Reply
For my new space, I just completed a diffusion panel and a reflection panel. Both were built to cover windows, look interesting and still provide a nice acoustic benefits. When I post them on the upcoming “Show Us Your Diffusors!” thread, I’m sure I’ll hear about how they aren’t correct or some-such baloney. Not like I would want to hang a single 3/4-based 42x60x8 300+ pound QRD with nothing supporting the back of it. There are plenty of things you can build that’ll help your situation.

mgraham70 – 07-20-2011, 06:05 AM Edit Reply
Originally Posted by garageband
For my new space, I just completed a diffusion panel and a reflection panel. Both were built to cover windows, look interesting and still provide a nice acoustic benefits. When I post them on the upcoming “Show Us Your Diffusors!” thread, I’m sure I’ll hear about how they aren’t correct or some-such baloney. Not like I would want to hang a single 3/4-based 42x60x8 300+ pound QRD with nothing supporting the back of it. There are plenty of things you can build that’ll help your situation.
Hey, whatever improves your situation! I’m looking forward to seeing what you’ve done.

Audio~Geek – 07-20-2011, 11:50 AM Edit Reply
looks great man. You’ve effectively talked me out of building some.

brandondrury – 07-24-2011, 02:48 PM Edit Reply
Do they have to be right next to each other, or can they be spread out across a wall in a checkerboard shape.
The way I understand it, QRD Diffusors are supposed to be in an array with the edges touching one another. This only phase one. I have 4 more of these finished and 2 more left that I’ll finish tonight to finish up this “one” diffusor. From there I plan on building 12 2′x2′ 1D QRD diffusors for the other three walls. I have some Gik ceiling tile diffusors for the top. I’ll keep you guys posted.
a difusor and bass trap to support it is only around $750 not ten grand from ethan. Buy one and build duplicates!
Correct, but I’m not positive that would be a better solution. Reverse engineering and rebuilding is a skill I’m not sure I posses particularly when it’s so easy to get the plans from QRDude.
Tackling diffusion is not for the timid. There are ways to identify specific room issues and formulas for dealing with the issues. I knew that diffusion was tricky but, Brandon’s articles have really shed some light on how deep, the topic of diffusion, really is.
Well, like a lot of things in acoustics it’s so complicated that it become simple again. I guess one could call it an “art”. The Tape Op article illustrates this. That guy even mislabeled the article “QRD Diffusor” when it’s actually a PRD Diffusor that’s been heavily quantized. He seemed to be really happy with his diffusors and he’s cut a lot of corners in his design. So it may not be THAT complex. I dug deep because that’s how I role and probably screwed them up anyway.
For my new space, I just completed a diffusion panel and a reflection panel. Both were built to cover windows, look interesting and still provide a nice acoustic benefits. When I post them on the upcoming “Show Us Your Diffusors!” thread, I’m sure I’ll hear about how they aren’t correct or some-such baloney. Not like I would want to hang a single 3/4-based 42x60x8 300+ pound QRD with nothing supporting the back of it. There are plenty of things you can build that’ll help your situation.
Awesome. I can’t wait to see this “show me yours I’ll show you mine” thread. As far as “aren’t correct” junk, I think there are specific methods that the math tells us will be more efficient or effective, but no one has come up with a Diffusion Coefficient to Happiness meter that I’m aware of. This acoustics business is too complex for anyone to be wrong, particularly if their mixes rock. I’m just a little scared of not bidding high enough so I try to go a little more ridiculous than necessary in the beginning.
You’ve effectively talked me out of building some.
The heat index has been around 105 for the entire week so I took some time away from mine. I started gluing a pair yesterday. I made it through one Viking documentary and halfway watched Lawnmower Man. So it seems it takes about 1.5 hours to just glue the 169 pieces. This IS a lot of work. I’m hoping not to ever have to do this again, though. Scratch it off the list and then conquer something else.Brandon

Brandon Drury

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Brandon Drury quit counting at 1,200 recorded songs in his busy home recording studio. He is the creator of RecordingReview.com and is the author of the Killer Home Recording series.
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