Sonarworks Reference 4 Review – Speaker and Headphone Calibration System

Here’s Eli Krantzberg’s review of the Sonarworks Reference 4 speaker and headphone calibration system that enables you to mix and master on your headphones with confidence.


The Sonarworks Reference 4 Calibration System

I have to admit, when I was first asked to review the Sonarworks Reference 4 calibration system, I was skeptical. The intended function of this software/hardware package is to calibrate your imperfect monitors to your imperfect acoustic environment.

It generates an EQ curve to compensate that you use to mix into on your stereo bus within your DAW. The idea is to ensure you are monitoring in as neutral a context as possible. So what’s not like? It sounds like a great idea!

I was initially skeptical; I realize now because I was fighting my preconceived notions about mixing and monitoring. No monitors are perfectly flat, and no room is acoustically perfect. You “learn” to work in your environment and that’s that. You learn to compensate through trial and error and experience until your mixes sound good. Period. Well, not so much.

You’ll have to read through to the end of the review to see how my prejudices have been modified through the experience of using this system.

So, What Exactly is Sonarworks Reference 4 All About?

First of all, Sonarworks Reference 4 comes in two flavors. The Studio Edition, which is what I used for this review, is designed to work on headphones and speakers. The less expensive Headphone Edition is a modified version, set up to work with headphones only. They also offer a premium bundle that includes pre-calibrated headphones with the Studio Edition.

There are four components to this calibration system. The first is the Reference 4 Measure app that resides in the Application folder.

This is what you will use to run the calibration routine to “measure” your speakers and their relationship to your room. Once it is done you will save this profile and load it into the second component of this system, the Reference 4 Plug-in. This is a standard plug-in, designed to be used at the last insert slot in your mixing signal flow; presumably the stereo bus within your DAW.

The third component is the actual mic itself, the omnidirectional XREF 20 measurement microphone that ships with the Studio Edition package. Each mic has a unique serial number that you will input into the downloads section of the Sonarworks web site. You are then provided with a custom profile for your specific mic that is used by the measurement Measure app when performing its acoustic measurements. The final component is a stand-alone application called Reference 4 Systemwide. Here you can load either your speaker or headphone profile so that all the sound running through your system audio is run through the calibration curve.

The Sonarworks reference system uses several advanced technologies to measure and calibrate your speakers; including the Automatic MicrophonePositioning System (AMPS) and Perceived Acoustic Power Frequency Response (PAPFR). There are a few more complex names and acronyms involved. But let’s skip that and look at how this system actually works!

Reference 4 Measurement in Action

Happily, Sonarworks holds your hand throughout the calibration routine with very clear on-screen instructions. First is to make sure the corrections are correct and there is no direct monitoring in place. Which is a very useful warning for someone using a UA Apollo setup like I am!

If you haven’t already, you are then prompted to download and choose your XREF 20 microphone’s unique calibration profile. After a few more audio interface setup prompts, the measurements begin. The on-screen graphics help you position the microphone to the necessary positions in relation to your speakers and physical setup. Finally, a profile is generated for you to save and use with the DAW plug-in and/or Systemwide app.

Mixing With the Reference Plug-in

Cards on the table here, it is a bit surprising to hear how different your speakers sound once you have the Reference plug-in set up on your stereo bus with your new custom profile in place. The EQ curve generated by the calibration process looked drastic to me. Could my room actually be this “bad”? I was assured by Sonarworks that this was not an untypical curve. Clearly, the positioning and acoustics in my room are affecting one speaker more dramatically than the other; at least down in the 150 cycle range. I’ll admit, I was reluctant and hesitant. I am used to trusting my ears with my setup in my particular room with my specific speakers.

I did an interesting experiment. I took a mix I did a month ago and remixed it with the Sonarworks plug-in in place on the stereo bus. It was a very revealing experience.

At first, I was startled that the level was so much quieter. I quickly learned this was a result of the default clipping protection that was enabled to compensate for the relatively dramatic curves needed to calibrate my set up. This was easily defeated by disabling the function and moving the output fader back up to unity output level. I used the same EQ plug-ins as in the original mix. But I found myself reaching for and adjusting bands that I don’t normally go to.

I have to admit that when I played back the final bounced version through my system on my IK Multimedia iLoud Micro Monitors, the new mix sounded really good! The moral of the story, for me at least, was to fight through your initial comfort zone being invaded and take the leap of faith. This system actually does work!

Using Headphones

I confess I’m not a huge fan in general of mixing with headphones, because they can be so colored and flattering to the sound. I used the same piece I used for the speakers and started mixing into a pair of Beyer Dynamic DT 770 Pro headphones without the profile in place. I got it sounding pretty good without too much trouble, which isn’t hard to imagine, given how nice sounding these headphones are straight out of the box. I then mixed it again using a custom calibration profile provided for this specific pair of headphones.

Unlike the speakers, I was very pleasantly surprised to hear that there was no immediate dramatic shift from the uncalibrated sound. I tweaked the mix using the profile. When listening back, I A/B’d the mix through the headphones with the calibration on and off. Happily, there was not a huge difference in the results; which I think is a good thing. There shouldn’t be a huge difference, given that there are no room variables involved.

What I did notice though was how the stereo imagining opened up with the Reference 4 calibration profile active. I really like that the difference was subtle. Not only did the imaging become clearer and more focused, but the frequencies seemed to even out slightly as well. I then tried the “average” Beyer Dynamic 770 Pro calibration profile that ships with the Reference 4 system. I didn’t notice a huge difference between that and the custom profile matched to my specific pair; although the custom profile did “feel nicer”. To be honest, I’m not certain if that was a placebo effect or not though


I wouldn’t hesitate for a moment in committing to the Sonarworks profile when mixing with these headphones. The subtle enhancement of the imaging and the nuance this provides in mixing is only apparent when mixing with headphones. I may have to re-think my ideas about mixing with them now!


Despite my initial apprehension, I can honestly say that I do believe almost everyone can benefit from using the Sonarworks speaker and headphone calibration system.

For inexperienced users, you will start off on the right foot; mixing to as neutral sounding speakers, or headphones, as possible. For experienced engineers who work on the road or in different studios, this is an invaluable tool. Simply run the Reference Measure app in your new environment and use the plug-in on your master bus. You will be able to rest easy, knowing that you are mixing in a consistently calibrated environment, despite the room or the monitors being different.

For experienced home studio engineers, and I include myself in this category, the benefits are also absolutely worth it, although we will have the hardest time taking the leap. It does require a bit of getting used to. But after a short time mixing with the reference plug-in in place, I forgot about it and didn’t notice it; and just went on mixing as I normally do.

The proof is in the pudding, as they say when you play back your mixes on other systems and hear how much more accurately they translate. There is a free trial available at the Sonarworks web site. If you have an hour or two to spare setting it up and mixing with it for a while, you will see and hear the benefits for yourself quickly enough!

For more information or to download a free trial, visit

Eli Krantzberg
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Eli Krantzberg

Apple Certified Pro Eli Krantzberg is an internationally known author and music software trainer for Groove3. His instructional videos have helped demystify music software such as Logic Pro, Pro Tools, Sonar, BFD, Melodyne, and Kontakt for thousands of users all over the world. Based in Montreal, Canada, Eli is involved in all aspects of audio production. In his studio he works with various artists, as well as on commercial jingles, corporate videos, and original music composition.
Eli Krantzberg
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  • I Multimedia has a mic/software combo called ARC which does the same thing. Very useful.

  • I’m glad you reviewed this. I’ve been curious about it but don’t have, really, any disposable income so can’t really afford to buy something I’m not sure about (don’t have a mic I’d feel comfortable using for the calibration so the trial wouldn’t do me any real good). I do trust your judgement though and this goes a long way towards nudging me in the ‘get it’ direction. Thanks1

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