Practical Approach to Acoustics, Rooms & Speakers

Acoustics. Rooms. Speakers.

A lovely field of black magic, isn't it?

Taj Mahal at SunsetWith acoustics, the theory tends to be clear and palatable, but the practice is usually an endless nightmare of random oddities. If I got a rupee every time I walked into a room "built by famous pro acoustician" but still sounded off, I could retire to India right now. Pass the Saag Paneer.

The acoustics of a room are so hard to predict that even the big name acousticians have to alter their designs and make sometimes drastic adjustments after the room is built when they finally get to listen to it. For smaller rooms the consensus is that it’s basically impossible to predict exactly how a room is going to sound until AFTER it’s built. And then it’s hard to unbuild. Right?

90's Studio Control RoomAs a result, a lot of control rooms in pro studios around the world are still quite flawed and difficult to get good translation from. Granted, there are weird considerations that have nothing to do with sound quality that often go into the building of those flagship rooms like, in no particular order:

  • looks
  • maximum SPL handling
  • real estate costs
  • looks
  • comfortable sitting and socializing areas
  • looks
  • maximum window opening towards the live rooms
  • sonic insulation from the outside

And then there is the big console problem plus the designer more often than not has to prioritize the way it looks above all else.

Egg Carton Recording StudioWorking in big pro rooms that sound off is always a fascinating and humbling experience, (especially since a lot of them still don’t have an easy way to plug headphones in the monitor section, but I digress) so if professional rooms built with good budgets are not perfect then what of home studios and rooms that are not purpose built? Well, they tend to suck. Pretty badly.

I was reminded of that very fact during the last pureMix seminar in my, quite accurate, room (which ALSO looks awesome, of course) at Flux Studios. The first part of the seminar was a listening session. Each participant brought a mix with them and I listened to it to offer them my feedback. It was amazing to hear the consistency of the problems in the mixes from person to person. Mostly low end problem, 200Hz/100Hz/50 Hz, big holes, big bumps, nothing that anyone dedicated to the craft like those guys would overlook. When asked, most the guys self diagnosed the problems in their mixes before I said a word. So why would they not fix it before they brought the mix over for scrutiny in front of a crowd of mixing geeks? And why would 16 different people with 16 different rooms all have mostly the same problems?

Because you can’t fix what you can’t hear and most rooms tend to suck in consistent ways.

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The problem is that most people repurpose bedrooms, basements or garages to create their mix rooms and those rooms are all more or less the same size and thus exhibit the same problems. It’s quite simple really. Even the more ambitious projects start with the existing structure's hand me down size and proportions that are rarely ideal. In short: building a studio is a gigantic and endless exercise in compromise.

90% of all home studios or mid level studios I have visited have undersized control rooms with ceilings that are too low. It’s a real estate problem. (Can’t push a concrete wall without great expense). Unfortunately, the smaller the room the nastier the problems that are generated and the harder they are to fix. Such is our life. So basically, you are kind of screwed before you even put your (pretty looking) desk in that spare bedroom/garage, basement/parlor apartment/etc...

So you start with a handicap, and then, there is the issue of the pre-existing window that is usually living on the wall where it’s least convenient (otherwise it’s no fun), and usually in a position that is really annoying (right at the point of first reflection for good measure), and there are the power outlets that are on the wrong wall so you can only put the desk where it makes least sense (otherwise it won’t look right, you know?) and then there is the nice couch you got from your mom (She expects you to use it no matter what, it’s a GOOD couch, she SAVED it for YOU, you know?) but of course it is just a little too big (3 inches maybe, just enough to prevent the door from opening properly), to put it in the best spot so it can only go there in the second best spot. And the list goes on, just like the beat. (Still moving strong, on and on)

And THEN you get to place your speakers. And then it sounds bad. And depression ensues because all you hear is bass or maybe you hear no bass.

Mix sucks in the carEither of these scenarios can happen depending on what the walls of your room are made of, the shape of the room, the color of your mother’s couch (It’s a GREAT couch), the speakers you use, how loud you work (the room sounds different at different levels of course, otherwise you could start trusting what you are hearing and that’d be too easy), and what you had for breakfast that morning. And so you mix, you conquer and then you step out to play your mix in your car and you seat in utter disbelief at what is coming out of THOSE speakers.

But what can an aspiring producer/engineer with a spare bedroom do against this tragedy?

Well, while it is not really possible to completely and perfectly fix an existing room without heavy construction, there are a few things we can do to greatly lessen the suck (Technical term)

Thing 1 / Buy bass traps. Lots of them.

While they help a lot, there are many problems with bass traps unfortunately.

The number one problem with bass traps is that they are a lot less sexy purchase than say, a Manley Massive Passive, and so people buy Massive Passives and have no money left for bass traps. Which is funny because without the bass traps you can’t really hear what the Massive Passive is doing anyway. Funny that.

The Force is strong with the Massive Passive but really, I venture to state that you’re better off mixing in the box on a laptop with small speakers in a room fitted with $20K worth of bass trap than in a room without bass traps and $20K of fancy gear. Try me.

This reality is hard to come to terms with for most people but it is what it is. Blame Physics. That’s what I do.

Here’s a test that could motivate you to think progressively. It’s fun and it’s free:

  1. Launch your DAW
  2. Create a session
  3. Instantiate a test tone generator
  4. Make it play a sine wave at 60Hz
  5. Play the sine wave at roughly the same level you mix at (Loud, right?)
  6. Slowly walk around the room front to back, left to right, corner to corner while paying attention (No status updates)

Oh JOY! Magic. Your 60Hz has been hanging out with Houdini. Isn’t that amazing?

Yup, there are places in your room where the tone literally goes away completely and places where it makes your head resonate, places where it feels like it’s changing color (It’s not, it’s a sine wave, you’re hearing things, literally) and places where it must be accurate. I’ll let you try and figure out which is where.

How did it sound at your mix position? Louder? Softer? Just right?

Try again with 80 Hz for extra fun.

Now chew on this: 60Hz is where a lot of the action is for a great sounding bass drum / bass relationship.

How much do you want bass traps now?

At least, please consider adding bass traps to your corners. All your corners. (The corner between the walls and the ceiling is a corner too). Corners are evil.

The second problem with bass traps is that they take a lot of room to be truly efficient at fixing the low end problems, and since the original problem already stems from having a small room to start with, there is only so much you can do in an existing small room unless you are willing to sit in the middle of an ocean of bass traps. Are you?

So (real) bass traps have some idiosyncrasies but they are the fastest and most effective way to fix a bad room. Trying it is loving it.

Thing 2 / Play with your speaker placement

These days active speakers put a LOT of bass energy in the room which further complicates things. If your room is small, go for smaller speakers. You don’t need a bigger speaker to have more bass, you need a better room. Think of Beats by Dre headphones, how big is that driver? How much bass does it put out? Right. Size alone does not matter, it’s about interaction of size, environment and desired level. So it very well may be that your speakers put so much bass in the room that you can’t hear it.

What?

Yes, remember walking around in your room and witnessing the magic disappearance of the 60Hz? (You did the experiment right?). Imagine that phenomenon on all low end frequencies. They all cancel out somewhere in your room. At different places. Imagine the mess. Now imagine that mess when you push the volume and the room gets more and more overwhelmed.

Messy.

So first, you have to pick the right speaker. It’s only possible to do while listening to the speaker in your room. Online reviews will not work. It’s like for mail order brides, it rarely works out from a distance. You have check out the personality of the other party in the final playback environment.

Then you have to put them in the right spot. (The speakers, not the bride)

In small rooms, it’s generally a good idea to follow two rules:

bass traps in the corner of a nice studio1/ Avoid the corners.

Again. Corners are evil. Do the 60Hz test and go put your head in the corners of your room. Enjoy the ear massage. No corners. They amplify bass and boost the energy in the room in a chaotic manner. Don’t do it.

Anyway, you can’t put the speakers there because the corners are filled with bass traps, right?

2/ Put the speakers as close to the wall as possible.

No, really, try it.

If you put your speaker against the wall it will work with the wall surface and enhance the speaker's bass response (yes, put yet more bass in the room) but you will also go a long way towards removing the biggest reflection that makes the most mess, the one from the wall closest to you, the wall behind the speakers.

Basically, these days, most (professional) speakers (made by reputable companies) deliver a fairly balanced spectrum. So if you picked a properly sized speaker for your room, it’s what the room does with it that matters, not what the speaker sounds like. Putting the speakers against the wall minimizes modes and nodes in the most cost /energy/time effective way. I promise it works. Remember soffits? There is science behind that concept.

Side note: you can’t really do this trick with rear ported speakers, only with front ported or closed box designs. Sorry Mackie.

3/ Move the speakers around.

(Not a rule, just a suggestion so we’ll stick to two rules and a suggestion, so there)

Suspend your (impeccable) sense of style for an hour and move ONE speaker around the room until you recognize what comes out of it as ‘mhhhh, not bad’. Sometimes you can feel it happening while you walk with the speaker in your arms (while it is playing music, yes). The speaker will start resonating or get louder or softer. Find a spot that feels right, then try to organize the room around that.

It is the opposite of how your set your room up last time I know, but try it, mix something, and go to your car to check out the results.

Do it. Then you can put everything back the way it was before your mom shows up. At the very least it’ll let you identify spots in your room that suck less than others and you’ll learn from it.

In my (very good looking) room, I moved the speakers 1 inch at a time for years until I found a spot that I like and that translates well. My room is quite big (30’’X 20’’ with 11’’ ceilings) and for workflow reasons I could not put the speakers against the back wall. The fact is that, even with its size, and depending on the speaker choice, my room eats some of the bass coming from the speakers when sitting at the mixing position. With my old Dynaudio BM15s it was hell on earth (they worked great in other rooms), with the Focal Twin 6 or SM9 it’s just right and I have not had a low end issue related recall in years. (The SM9 does not work as well in my downstairs room because it’s too small. Bummer).

4/ Do not attempt to measure the room precisely with RTA software.

Unless you have a very strong mental and physiological constitution (This is healthcare advice, which does not count as a rule, so it’s still two rules, one suggestion and some healthcare advice. Pay attention please)

Don’t measure your room with a makeshift RTA system. Don’t do it. It will ruin your day. Guaranteed. Potentially your life, I think. It’s possible. I have seen it happen on the internet.

Anyway, measuring your room with homemade RTA capabilities will not bring you anything other other than depression, destitution, misery and deep sense of worthlessness.

Because:

A/ All rooms suck, both in frequency response and, worse, in time domain response.

Your room sucks. I have not been there personally, but I can assure you it does. It’s 100% sure.

The only debatable variable is how bad does it suck? I do understand the urge to know everything is details but:

B/ Since you probably don’t know how to read the RTA results in a constructive manner (I don’t really myself and I have made efforts), you are not going to be able to act upon those results in any real manner so basically you are putting yourself in a position of an indentured victim with no power to escape the ironclad rules of acoustics.

C/ And, even if you know how to read the graph (You’d have to know how to read the frequency plots, especially which sensitivity and octave settings to use to not drive yourself insane, know how to read the time domain waterfall, understand the difference between full bandwidth, sweeps and single frequency tests, etc, etc…), even if you do what I'm saying, following the above formidable advice will get you most of the way out of Compton using normal quite affordable resources. You don’t have to be a victim to TMI (Too much information in LA parlance)

In this case and in this case only (except maybe for some mail order bride cases):

Ignorance is bliss.

In my personal long and painful experience, knowing how bad your room sucks is about the same as knowing how many bugs your DAW has. Not useful. Not enlightening. Just depressing.

What matters is translation. And fun. Ultimately, it does not matter if your room is not perfectly flat as long as you can deliver mixes that sound great everywhere, and the journey to get those mixes is a blast. Period.

So, since your room is most likely a problem, try the above steps before you try anything else like heavy drinking or hard drugs. Those won’t help much (for your room that is) but there is a way out: Bass traps in the corners, tweak speaker placement, mix and compare. Make progress. Enjoy life.

Don’t sweat the details and don’t let the 1/24-octave-RTA-bring-you-down, no no let’s go.

 - Fab Dupont

Have you treated your room or moved your speakers around lately? Getting better low-end response? Tell us about it in the comments

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