Diffusion: At What Point Should You OBSESS Over Acoustic Treatment?

Brandon Drury —  June 4, 2011 — Leave a comment

All of us home recorders seem to follow a fairly similar path. We get started, get overwhelmed with the mess of choices and try to put a setup together. (If you are still in this rut, make sure to download my freebie Killer Home Recording:Setting Up. )

The few, the proud of us who make it through that mess begin climbing the Everest known as audio engineering, producing, psychology, soldering, wood working, Windows (and, yes, Mac) troubleshooting, marketing, taxes, low-level physics, music theory, drum tuning, synth tweaking, song writing, and a billion other stupid crafts that all merge into this one.

I don’t know one person cranking out full-blown ultra-A list mixes where I say, “Wow, dude. That’s BETTER than the big boy mix on X Grammy-winning production.” I know some guys doing DAMN GOOD work, but if I had a budget of $500,000 to mix the record, I’d go up the ladder. My point is that everyone here at RecordingReview is still growing.

Because of this persistent growth, I think it’s REQUIRED every once in a while to rethink where we are in our quest. What fundamentals are we getting right? Where have we totally dropped the ball? What things got pushed down the list and need to be pushed back up? Where have we gotten sucked into things that don’t really matter?

This week I’ve been thinking about diffusion and little else. I mean I just piss my pants because I forget to go to the bathroom because I’m trying to figure out the ideal quadratic residue numbers for my upcoming diffusor DIY project.

What set it off was a certain video from Ethan Winer of Realtraps. I honestly thought I had seen every video of Ethans (and read every article). It appears I missed the big time, ultra home run video. I missed what appears to be the life changer, and honestly, my life hasn’t been the same since I’ve seen this video. I have a “vacation” tomorrow and I’m STRESSED because I’d much rather be building diffusors.

The Life Changing Video

First, if you’ve never recorded the sound of your studio monitors, I highly recommend you do it. Play a kick butt, major label recording, toss a mic 4′ away, and capture it. Then mute the real thing and play back your recording. Unless you’ve been blessed with a silver-spoon-room, you’re probably going to go, “Ouch!”. I’ve done this test many, many times. It hurts no less each successive attempt. I’m batting zero.

Diffusion Video At Real Traps

- First, the first dude looks EXACTLY like a character off of the Garfield cartoon. It’s probably blinding lights, but I got a kick out of this none-the-less.
- Second, the video is over 10 minutes. If you are in a hurry, head to 6:00 mark. This is where my life changed, but there is BIG TIME value in the entire thing.

Note: I had TOTALLY forgotten about that Eric Johnson song. Awesome.

The Real World Application

I’ve done nothing but research this diffusion business, trying to figure out if these diffusors are something I should build or if I should just cough up the cash for the Realtrap diffusors.

Here’s where life gets interesting.

Here we’ve got new guy to, Zackykins, struggling with recording drums in unideal situations.
If you listen to his clips, they are quite boxy. (Give him a break. He’s new and his drummer isn’t exactly Josh Freese…YET.) I’m not picking on the dude. Just make a note this this guy has real gadgets for recording drum and that’s the results he is getting.

Then in my research for QRD (Quadratic Residue Diffusors) I stumped upon this.

Take note of the elephant in the astronaut suit in the room. I’m referring to the mountain of 2D QRD diffusors in the wall separating the drummer from the control room. Awesome! Even if they sound like a gripey wife, they still look cool.

Notice the crack in the snare and the overall “alive” vibe to the kit. When have you ever heard THAT in a video camera mic? I can count once and it’s this video right here. Don’t get too wound up about anything else, it is a video camera mic 2′ from a drum kit. The point is this overloaded camera mic sounds better to my ears than the real condensers in the drum thread above and we’ve rules out engineering skill in this situation. This room is doing something and it’s doing something AMAZING!

We can only speculate what all has went into that particular room (he obviously has some GIANT Helmholtz resonators too), but it’s clear that the they were not shy with their use of diffusion.

The Struggle

I’m in an odd situation because one of these days I’m going to quit blowing cash on gear, buy some land, and build my superstudio. This temporary setup has made me lazy in the acoustics department. However, it’s clear to me that I need to include diffusion into my current setup NOW.

I’ve been fighting boxy sounds, unfocused sounds (the same sounds in the Realtraps vid of a room with absorption but with no diffusion) from day one and this is something that still fights me even with Neumann, API, and the fancy console.

Options In Diffusors

There are a few different ways to go with diffusion. Realtraps offers what seem to be highly effective diffusors that look badass (particularly the black ones) but will cost you. Gik offers some options that seem quite effective, too, but at significantly less cost. I can only speculate as to their performance. RPG is kinda the big dogs when it comes to this diffusion business, but they seem to be going after the Wall Street CEO market.

The final option is to build ‘em yourself. This is a route I’m contemplating. The work load is high. They aren’t dramatically cheaper (depending on your design). There is always the risk that you miss some small detail that renders all your work entirely ineffective. Even worse, you may build them perfectly and always wonder if you screw them up.

Announcement: For the first time in history there is something of value posted at GearWhores. This thread is a monster. If you are intimidated my math, charts, and outrageous attention to detail, it may be better to let the pros handle the diffusor construction.

Back To WHEN

Back to the original point of this article. WHEN is the right time to start obsessing over acoustics, conquer absorption, and then move over to the not-so-set-in-stone world of diffusion? The day you that ask, “How do I make this thing sound better than this?” is the day. If you find yourself looking at catalogs, I can tell you right now that you’ve made a wrong turn. Forget fancy mics, preamps, compressors, and plugins. Figure out this diffusion business NOW….at least that’s what seems to be the case.

Very soon I’m hoping to report that life without diffusion is like life without a penis. We’ll see…. says Confucious.

Stay Classy!

Categories: Tactics And Concepts, Audio Mixing Tips, Acoustics and Studio Construction
Tags: acoustics, diffusion, diffusor, gik, helmholtz resonator, realtraps, rpg

Saved Comments

EQThis – 06-14-2011, 08:54 PM Edit Reply
Good article Brandon. This has been on the back of my mind too but hasn’t quite consumed me…yet. Can’t wait to hear about your results. Tape Op also had a good article on DIY QRD/BBC diffusors in this month’s issue #83. They seem to make it simple enough, but I haven’t decided if the time commitment is worth what could be a miniscule improvement to a small studio. Also, I’m not recording drums. Best of luck.

TheMandalaVirus – 06-15-2011, 09:11 PM Edit Reply
Great article. A very unappreciated aspect of recording. I read a GREAT, retard friendly article on building your own in tape op magazine. I scanned the article, it’s just in a few sections. Here’s the link: DIY Diffusors

BlackCatBonz – 06-17-2011, 11:40 PM Edit Reply
I have been doing a lot of reading about diffusers as well. At the moment, I don’t have money for crazy expensive mic’s and pre-amps… The next logical step is having a great sounding room, I don’t have any money for room treatment either; but I have been building things for 25 years.
Once the mother-in-law moves out, I am going to turn her apartment into a studio…. It’s not a huge space, but it has a bedroom and living room that would make an excellent recording space with the right treatments.
Ethan and Doug have a great video “The Ultimate Home Studio” detailing what you can do in a home studio with some acoustic treatment, you don’t need a monster room as long as the room sounds good.

I also stumbled onto a site called Subwoofer Builder that has a few pages on Diffuser calculations and building.

It’s a great site if you don’t feel like trying to wrap your head around the math and want to get to building (I prefer figuring everything out myself because I am a ridiculous nerd). If anyone builds a few of these, please post some pics.

mgraham70 – 06-18-2011, 08:38 AM Edit Reply
Great article! Yeah, carpeting, egg cartons and foam pads just don’t cut it!I’ve been a follower of Ethan Winer for years. I studied his work and theories, extensively, before I built my studio. I did my best to figure out my own designed traps, based off of what I learned from Ethan. I doubt that my designs is as good as his but, doing it myself allowed me to have significant room coverage, which I needed for my relatively small rooms. I would’ve loved to purchased his traps but, there was no way that I could afford the coverage that I needed. I did the crude math and it would’ve cost me at least $24k to purchase the kind of coverage that I needed. Ethan’s traps are worth every penny of it. I just didn’t have it to spend. I don’t know how my designs stack up against his but, I’m glad to say, my traps have made a dramatic difference in the quality of my rooms. If you’re curious, you can see some of the traps, that I designed and built, in my studio photo album (in my profile). I’m most proud of my drum room (picture #7). I would still love to (hopefully someday) purchase some of Ethan’s diffusor/traps.Ethan is the man!

.tom – 06-18-2011, 11:44 PM Edit Reply
“I have a “vacation” tomorrow and I’m STRESSED because I’d much rather be building diffusors”

heh you got it bad. that’s a good thing

Danny Danzi – 06-19-2011, 08:50 AM Edit Reply
Brandon, I’m gonna go against the grain here a bit. You and everyone else will probably disagree with me. However, having worked in some pretty incredible rooms in my life recording drums, “the kit” as well as the tuning, mics used AND the player is what made the difference way more than any room I’ve recorded in. Though a room and having control over that room is important, in my experience rooms have not made a huge difference for me as much as the other stuff I’ve mentioned.
I keep reading people mentioning rooms as being so important when they record yet if you listen to most of the big guy productions, the instrumentation is up front and in your face. You don’t hear loads of room coming into the play at all…you really don’t. Now, in some instances, you may hear some room in a snare which replaces putting a reverb on it…but is what you are hearing the room, or a really good impulse or a verb? Seriously man, listen to the new stuff of today. Those snare drums crack right up front in your face and if the drum is ringing, it’s because of the snare used, the way it was hit, how it was tuned and how it was captured.

Trust me, you get a killer drummer with the right kit, the right tuning and the right mics on it, it ain’t gonna matter what room you’re in unless the room is so bad, it makes the over-heads sound like total dog crap…which even still, can be remedied. With all the right stuff, I’ve had the same results in a room that wasn’t so good as a room that was perfect for tracking drums. You figure, with close mic techniques, you could add impulses anywhere you wanted and then eq them. I’ve done this with OH’s as well on some rooms that were super tight sounding. There are 2 big studios that I work out of around here that have killer drum rooms. In one of them, they double booked 2 bands for the same night, so we had to use another room within the studio for the drum kit for this other band who wasn’t as “important” as the other so to speak. When I was done tracking the drums in this 16×16 room that didn’t have anything in it, the sound was incredible.

The studio owner didn’t know about the double booking at the time and had just updated his main room with all kinds of goodies. He says to me “wow, those drums sound insane…the new room really made a difference, didn’t it?” Then I shared with him what had happened….and he just couldn’t believe I got the sound I got out of this other crap room that was used at one time, but was pretty much used for storage. They had snakes in there still functional so it was easy for me to remove the crap in the room, set up a rig, roll some racks in and do what needed to be done.

But to me, that little crappy room sounded just as good as the big pro room with all the goodies in it. The kit was a DW kit with a drummer that knew how to play and how to tune the drums. That there makes it possible to do just about anything without having to rely much on anything. I could have put 57′s all over that kit and it still would have sounded incredible. When dude hit that snare drum, he hit it like it was his last day alive. Just the right amount of ping and ring in it. Freakin’ rim shots were off the hook…the toms resonated perfectly, he had a great cymbal rig…it was nearly impossible to blow making this kit sound good…and we did better than good, we blew the engineer running the drum recording in the big room, completely out of the water.

Danny Danzi – 06-19-2011, 08:51 AM Edit Reply
Hmm, I spaced out my paragraphs in that post perfectly. It seems to have disregarded them though. Do I have to use html or something to get it to space properly?

***Edit*** Ok, I fixed it.

brandondrury – 06-21-2011, 02:56 PM Edit Reply
Hey Danny,It sounds to me like you are working in good room already. ….regardless of size or the way it looks. The only real issue with this acoustics stuff….or at least the one sound that I haven’t been able to find a creative use for are the comb filtered early reflections. They always murk everything up and I my natural reaction is to boost upper mids to fight through them, even though that’s not the right solution. What I liked about the video clip that Ethan created was it illustrated the EXACT sound of this boxy, murky crap and that was a room that already had absorption. The room with diffusion was a zillion times better and based on the video I’d rather work in the with-diffusion room every single time. No question.This doesn’t mean that everyone needs diffusion and I’d guess that not all people are suffering from this problem. I’ve recorded on location many times and not had to fight through those troubles. It makes life REALLY fun. The tricky part is identifying the real problem. As you’ve noted, there’s a zillion more that goes into the chain, but it’s safe to say that the room is going to have an effect on every track you record with a mic, for better or worse. The other side – the one I’m facing – is too my absorption sucking all the fun out of the room and that leading to big time troubles. Diffusion seems to be the answer for that. I’ll be able to tell you in about a week or so if I wasted my time and money.
toms resonated perfectly
This is another huge one. I find that any good engineer can fight through kick, snare, and cymbal problems with work and a few good tools. Toms seem to be most sensitive to the room (in terms of this early reflection business). I’ve heard drums that went from tons of attack to ZERO attack just by switching rooms. It does happen. The tuning can be adapted to the room, but even that is a compromise.

sparqee – 06-21-2011, 04:11 PM Edit Reply
Two years ago I got fed up with my room tone. I got a bunch of books, spent late hours searching through Gearslutz (what a nightmare). Learned a ton of stuff but finally decided that I would rather write music than study the dark arts of acoustic treatment. A month later I heard a podcast interview with an acoustics consultants and since he was offering a discount to listeners I bit the bullet and hired him. A week of back and forth emailing of photos, measurements and impulse response testing and he sent me a very well documented “to do” list. Now that I’ve finished installing the treatment (some DIY, some purchased) I can say I’m happier with both the sounds I get through my mics and the ease of mixing (I do both in the same room). It really was a satisfying combination of DIY construction, self learning, advice taking, and instruction following. All told I think I spent around $700 US between materials and consulting fees. Well worth it for me. If anyone is interested the consultant’s name is Gavin Haverstick. Check out his website. He’s a very nice guy and taught me a lot. – Sparqee

.tom – 06-23-2011, 10:27 PM Edit Reply
I agree with Danni Danzi’s post – the tuning and quality of the kit is most important, next to the quality of human.. hehe special breed, rock drummers.but, I do want to explain something I’ve observed recording musicians & instruments; early reflections & their frequency response are very much a part of what makes that snare clear and full. in this case, the diffusion is a good filter, it has several hundred reflection times by design as this flattens response as does the varied radius of each corner in that room. those drums are tuned nicely and the cam does have a soft limiter circuit that reveals rooms and response a bit better than ppl might, yes, Danni is correct – the major contributor to great drum sound is the drummer & the kit plus tuning, but Brandon is also correct when he points out he’s working in a squared, modal room and adding diffusion etc will certainly make a big difference in drum me, when it comes to recording drums, it’s about early reflections. even in the mix and setting up reverbs for drums it’s about early reflections.

brandondrury – 06-26-2011, 05:41 AM Edit Reply
I think it’s important to note that anyone taking this recording thing seriously doesn’t care about the most important factor. They care about ALL the factors. Trying to figure out if it’s the amp or the guitar player that make the tone is always a messy thought experiment as both are required. Killing either is going to probably get in the way of a great recording. The hard part is identifying your weakest links. I do think that mega musicians with mega performances will always be the name of the game, but I no one really wants to record these kinds of performances in a cardboard box. So I think a discussion of acoustics is highly important….even if everything else is too. Brandon

mgraham70 – 06-27-2011, 08:32 AM Edit Reply
Originally Posted by Danny Danzi
Trust me, you get a killer drummer with the right kit, the right tuning and the right mics on it, it ain’t gonna matter what room you’re in unless the room is so bad, it makes the over-heads sound like total dog crap…which even still, can be remedied. With all the right stuff, I’ve had the same results in a room that wasn’t so good as a room that was perfect for tracking drums. You figure, with close mic techniques, you could add impulses anywhere you wanted and then eq them.

I agree with Danny about the kit and the drummer. A properly tuned kit goes a very long way and a drummer, who knows what there’re doin’ and how to do it, can still sound musical and impressive on anything, anywhere. Just watch the opening of Benny Greb’s “THE LANGUAGE OF DRUMMING” DVD… where he randomly creates some very impressive rhythms, on items in his kitchen. With skills like that, the mind is very forgiving of the sound quality.

However, I disagree with Danny’s “one size fits all” mindset, regarding sound and mic placement. Yes, decent to great sound can be achieved in almost any room, with close mic techniques…. but not everyone always wants that “right on the head” sound, for everything they record. Furthermore, some room’s dimensions can be modally out of control and phase cancellation can wreak havoc on almost any mic placement. I agree with Brandon, your “not treated” room is probably a pretty good room to begin with.

In my case, my drum room is so small (approx 9′ x 14′ with an 8.5′ ceiling), the placement of traps made a DRAMATIC difference in the ease of getting great sounds. Sure, maybe someone with sharper engineering skills, could deal with my room (untreated) but, I believe that traps and diffusion opens up your options and makes achieving those options quicker and easier. Wrestling with technical elements (almost) always gets in the way of getting to the creative elements (arguably, the most important thing).

Side Note: I have a great sounding Pearl Masters Custom kit that sounds amazing and I take great care in tuning it properly. Before the treatment of my room, my bass drum sounded really good and full but, I struggled with capturing a punchy yet fat/tonal sound. The common punchy, “clicky” sound was easy to achieve. After treatment, I have a surplus of “tone” in my bass…. I actually have to dial it back. Hip Hop is not my thing but, I bet I could make Hip Hop samples, if I wanted to. My options are extremely wide, now.

Treatments may not be a “necessity” but, they sure as hell add to the end quality, flexibility and ease of achievement, for me.

dudermn – 07-03-2011, 06:47 PM Edit Reply
Modern ways of thinking of diffusion don’t exist? Seriously Sound-waves travel as SPHERES!!!! Dammit People.
So if you take a sphere and throw it at a freaking square at 600 mph what happens ? Try throwing an orange at a knife for starters. Hasn’t anyone discovered spheres yet for home recording? (and no not circles)
Though I can’t be one to brag I don’t use any type of standard insulation or industry standard monitors. Heck I drink more than I work . Now than, how bout evolving this thing, and using sound reinforcement over diffusion.
I.e. Capture the sound, restrict it’s ability to emit back to point A, emit from the direction of desired diffusion captured sound without the degradation of altering sound frequencies.
So… Take a big mattress pop it in the corner. Put a microphone in front of it, and a another good ol fashion monitor. Set that up with it’s own ‘mini-p.a.’ system and do that for where-ever you want diffusion. Heck, you can even run an effects rack and pretend to be in the Taj Mahal (digitally of course). (Bose did some studies with their little sonar acoustic radio….) Anyone ever herd of tuned metals by the way ? I.e. Have a desk that upon hitting with your head ‘oscilates’ within the 440s (or 1320 or 220s) ????? Great article, I really liked the onslaught of material too. Now to watch the video with “the guy from garfield” You ment the author
I really like the part with “if you ever recorded sound off of speakers and herd it sound offphase” How he turned studio terms into everyday English is GREAT

IMF OnSite Recording – 07-04-2011, 04:40 PM Edit Reply
Some drums actually sound great in the right UNTREATED room due to natural reverb. How about When The Levee Breaks by Led Zeppelin? That was actually recorded in a stair well with microphones going up the stories. Now that is a natural effect placement and I find that to be more creative than a raw sound put through a fake reverb. However, a diffused room is universal and caters to musicians of all tastes as all things are rendered after the recording.

brandondrury – 07-05-2011, 02:14 PM Edit Reply
Some drums actually sound great in the right UNTREATED room due to natural reverb. How about When The Levee Breaks by Led Zeppelin?
Agreed 100%!!!Until the day people are talking on blogs about how classic Brandon’s drum sounded in an UNTREATED room, I’m going to work on solving the inherent problems in my rooms.In Recording Studio Design, this issue of treatment vs non-treatment comes up. Basically, an untreated room that’s big enough not to be contaminated with comb filtered early reflections is going to have X character. Everything recorded in it will have it. I think we can all agree that maybe not every song should have the When The Levee Breaks sound. In particular, Angel of Death would sound like Angel of Crap in a hurry. So the more neutral approach seems to work best when we are doing Slayer one day and Fleetwood Mac the next. 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 and is the author of the Killer Home Recording series.

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