Reference 4: Room EQ Made Simple

Mike Lawson • Technology • January 10, 2020

If you follow any of the online groups on music production, you know a day doesn’t go by when someone doesn’t ask about what gear they should buy for their studios. The responses predictably include everyone’s favorite mics, plug-ins, and speakers.

But then someone with a little more insight will chime in and say, “don’t worry about gear before you take care of the acoustics in your room.” This is very good advice. It’s tough to create a decent mix that can translate to different playback systems when you aren’t hearing the sound accurately.

Professionals know “it’ll all come out in the mix” is a fallacy, but they also know a poor mix can ruin a good song. Yet, mixing is something that often doesn’t get a lot of attention in music tech classes. One reason is that so much time has been spent on getting the music right–after all, we ARE music teachers—that there just isn’t time to give mixing the attention it deserves. But another reason is that it’s not easy to teach mixing in a classroom environment. Students are usually working on headphones, and even when using speakers, the acoustic environment is less than ideal.

The truth is that all playback systems color the sound somewhat. Professional studios pay a lot of money to design rooms with excellent acoustics, and engineers spend a lot of time learning the sound of their studio. Live performance venues have graphic equalizers that are permanently set to adjust the system to the hall’s idiosyncrasies.

For the rest of us, it’s more or less guesswork. We don’t have the budget to hire acousticians, and while the average music tech teacher understands sound, measuring and tuning a room is beyond what most of us can do. So at most, we add a rug, hang some drapes, maybe even invest in some basic acoustic treatments. This helps, but we don’t really know what the results are. Until now.

Reference 4 by Sonarworks provides the easiest solution to room equalization I’ve ever seen. The program measures the response around your listening point and then adjusts the playback to provide an almost perfectly flat output.

What’s in the Box?

Opening the box of the full version (€299, $179 educational)‚ is a little disappointing at first glance, as all you see is an omni-directional reference mic and a card with a license number. After downloading the software–there are two apps, Reference 4 Measure, which creates profiles, and Reference 4 Systemwide for playback–from the Sonarworks website and authorizing it, you’re ready to get started.

There’s no manual, but you won’t need one. Just open Reference 4 Measure and follow the instructions. You’ll first see a checklist to make sure your system is ready. You need an audio interface set to 44.1 kHz that can provide phantom power to the condenser mic. Next, you enter the ID number for the mic. Sonarworks has its frequency response profile in a database and automatically applies it to the calibration. Next, you’ll choose the input and output devices, set the levels, and then are shown how to position the microphone to get the most accurate measurement. All of this takes less time than it did for me to write this.

Ready, Set, Test

Now for the fun part as you start measuring. The process takes between 20 and 30 minutes. First, the software measures the distance between the two speakers and the between the speakers and your listening position. Then you begin measuring the response for 37 different points encircling the listening position. It displays a point on the screen, and you move the microphone to the point. The software shows when you are in position, and then it emits some tones to complete the measurement. It’s incredibly easy to use and has a bit of a video game quality to it. Once all the measurements are completed, it shows you the response profile of your room and the calibration it will apply. A nice feature is that the left and right speakers are calibrated independently. I tested the software on a variety of rooms. The first was the studio control room with a pair of Genelec 8040s and a Genelec subwoofer. This room has been problematic as the dimensions are less than ideal, and the glass is too large, but it’s been treated with absorptive walls and bass traps. I knew from experience that it tended to have a bit of a bass bump and the software confirmed that. But I hadn’t been aware of a dip in the mid-range it identified. As a result, I decided to measure the studio again with similar, though not identical results, the variation likely due to slight changes in the mic position while measuring.

Next, I tried it out in our mixing studio. This room has a pair of Adam A7x speakers. It’s a better listening environment and the software again confirmed that, but it also had a noticeable dip at around 1 kHz and the bass roll-off began at just under 100 kHz. With the completed profile, you can run apply the calibration system-wide or as a plug-in in your DAW. One odd thing on Mac is that when the Systemwide version is running, it won’t let you choose a different output in the Sound control panel until you disable the software.

The next thing to do was listen. I took a couple of mixes that I was thoroughly familiar with and began playing them in both rooms. First, comparing them in each room with and without correction and then from room to room. The results were remarkable. The difference with and without the correction was significant, but the correction was clearly more accurate. The differences in the two rooms have caused problems for students in the past, and this will help relieve some of the scheduling bottlenecks.

Suitably impressed, I decided to really put it to the test and tried it out on my home practice room, a small bedroom with a small pair of Presonus Eris 3.5 speakers. The room is untreated and has some real problems, including some nasty resonances at around 150 Hz. To be honest, I didn’t expect it to help much.

But to my surprise, it did a pretty good job of taming those resonant frequencies, and while It’s still not on a par with the treated rooms at school, it improved the sound quality significantly. I had my recording class do the last test. We tried using it in the studio live room with its playback system, a pair of Dynaudio L48s with an 18s sub. This is a considerably larger room and is very dry. We chose a listening point that created an equilateral triangle between the listener and the speakers. But when calibration was applied, the sound was significantly diminished and unbalanced. From looking at the profile, it’s clear we had found a node on a standing wave as there was a large bump at around 80 Hz. It ended up being a better lesson than I anticipated.

Now, this is all great, but there’s one more feature that sets this apart from other room EQ software. Reference 4 also includes profiles for many of the most popular pro-quality headphones. I tried it with our HD650 and ATH-50x. Once again, the resulting sound was quite similar, even though they are significantly different cans, one open-back, and the other closed-back. More importantly, the overall sound of the mixes was quite similar to what I heard on speakers.

Room for Improvement

There are a couple of minor issues. One thing is that the final results aren’t going to be perfect. Since the mic is hand-held and moving, there will always be some human error caused by the placement. The measuring locations are presented as circles with a point in the center. This makes it easier to hit the target, but also means each time you measure, there will be some slight variations. Moving your body to the correct spot while keeping the angle of your arm consistent will result in the most accurate measurements.

The other issue is something that only will relate to schools. On Mac, the software authorization is placed in user accounts. That means if your students have individual logins, the software  needs to be installed and authorized for each account. It would be much better if the authorization at the system level.

The Grade

Music technology today increasingly means audio production, and with that evolution, the art of mixing needs to be given more and more attention in music tech classes. Reference 4 makes it possible to create accurate mixes in the classroom or the studio. For school labs, there is a headphone only version for S49. Now that I’ve used it, I can’t imagine not having it. I give it a solid A+.

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