How to Test Your Mixing Room

The way a room sounds has everything to do with how we perceive the sound in the room. A little bit of natural reverb in a tight space (like a tile shower) can inspire even the shyest singer to start belting out their favorite Fleetwood Mac hits. The best speakers in the world put into a crappy sounding room are probably going to sound pretty yucky. Let’s work on some acoustics.

How can you figure out what’s wrong with a room? How do you fix the problems?

You can do all of these tests with your naked ear, but to keep it strictly scientific it’s a really good idea to spend a few dollars ($50) and get an SPL meter. (Radio Shack) This device is designed to give you an accurate reading of how much sound pressure is happening in a single place. It measures in SPL which stands for Sound Pressure Level. Sound above 100 SPL can cause permanent damage. The ideal listening levels are between 80 and 90 SPL.

Download some test tones so that you can have an accurate idea of exactly what you’re testing. Here are some test tones that I routinely use: Test Tone Downloads

You’ll need to download the mp3’s that you want to use and then play them through the speakers that you mix through. A good first mp3 to download is the 20Hz to 20Khz Sweep. This is a ten second sweep from the lowest sound people can hear to the highest sound. When you play this file through your speakers you will probably notice that the tone will start out as inaudible and then the volume will sound like it’s going up and down slightly. You will probably notice that some of the loudest parts of the sweep are the most annoying frequencies.

So here’s the weirdness: the test tone is recorded at an equal volume across all of the frequencies. What you are hearing as volume increases and decreases are inaccuracies in your speakers, resonances in the room you’re in, and possibly that all those Metallica concerts may have actually destroyed specific frequencies in your hearing.

First Things First

Make sure that you have set your monitors up in the correct way. Here’s a good check list.

  1. CABLES. Use high quality balanced audio cables to connect your audio interface or your mixes control room outputs to your monitors (if your monitors are active) or your monitor amp (if your speakers are passive). Make sure that the cables are the same length and the same type of cable. If you are using passive monitors make sure that the speaker cables are high quality, as thick as possible and that they are the same length.
  2. PLACEMENT. Your speakers should be placed roughly at ear level. They should be the same height. You should always sit in the same place every time you mix or listen. You should sit so that each speaker and you make an equilateral triangle, meaning that all sides of the triangle are the same length. The speakers should point to where you are sitting.
  3. DE-COUPLING. If you put your monitors on a table and play music the speakers will vibrate, so the table will vibrate, and everything on the table will vibrate. There’s a resonant frequency for everything, and your table probably doesn’t sound wicked good. At a bare minimum you need to get a piece of heavy foam to put underneath the speakers, this will minimize the amount of energy that gets transferred from the speakers into the table. I have had good luck with using heavy mason’s sponges that you buy at any hardware store. You can also buy products like:

    Auralex MoPad

    Vib X

Ok. Now your speakers are hooked up right, placed right and sounding as good as they can on their own. Now you’re ready to start doing your testing. First try playing the test sweep again. You probably will notice some improvement already.

Here’s the flow of the testing. Start with your mixer set to unity or with your interface set to unity and start going through all of the test tones. The ones under 500 Hz tend to be the ones that are the most screwed up. I usually start by playing a 1Khz tone and then recording the SPL. Measure the SPL with the meter right where your head is when you’re mixing. Adjust the volume of your monitors until the SPL is close to 90. This will be your baseline. Now you know that when you play a 1 Khz tone at -12 dB it’s sounds in the room at 90.

It’s a good idea to mark down where your volume knob is set now. This is where you want to do most of your listening. Now simply repeat this procedure for as many tones as you can stand. I usually start low and work my way up. Write down which tone you’re testing and what the SPL meter says.

Now you have a pretty good idea of what’s happening at your mixing location in the “sweet spot.” Next time we’ll go through what you can do to fix the problems that you’ve found.

2 Responses to “How to Test Your Mixing Room”

  1. cory Says:

    i know this is an old post but, on the topic of decoupling, i have found out that the best isolation pads for desktop monitors come dirt cheap from your local HVAC supply house (you know, the place you get your duct board and 703). The thing your looking for is A/C condenser vibration pads. they are designed to handle almost every frequency heard from equipment that can put out vibrations on a level way larger than your speakers ever could. they also make amazing wall treatments. when a new local radio station moved into town the guys at my local supply house told me the engineer at the station had bought well over $10,000 in the things for wall treatment because “they are simply the best at it”

  2. admin Says:

    I have tried some Vib-X neoprene pads that worked fairly well. The problem with these types of pads is that you need to make sure that your monitors are heavy enough to compress the pad a little. A lot of these neoprene pads require a LOT of weight in order to compress enough to work well. In other words, the spring needs to be compressed a little to isolate. If it compresses too much it doesn’t work, if it doesn’t compress enough it doesn’t work. So you need to make sure that the pad is rated to work under the same weight as your monitors.

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