• Price: US$99 for Headphone Edition, US$299 for Studio Edition
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Sonarworks Reference 4 Calibration App Review

Joey Santos
Read time: 4 mins
Last updated 3 November, 2021

The Lowdown

Sonarworks Reference 4 is an application that attempts to “flatten” the sound of your headphones and speaker monitors to give you a more accurate listening experience when you’re producing. It does this by correcting the frequency peaks and dips in your speakers or cans. It’s a great idea in theory, and in practice it is able to do the frequency corrections, lessening the bias and characteristics in favour of a more neutral sound. The result is that the app makes it easier to hear and tweak nuances in your mix using your existing playback system. It’s a fantastic tool, just adjust your expectations – in other words, just don’t expect it to turn a cheap pair of headphones into one that costs thousands of dollars.

Video Review

First Impressions / Setting up

All headphones and speakers have a “signature” sound: whether that’s a bump in the low end for more bass (as is the case with DJ headphones) or a dip in the mids and a spike in the highs and lows for that “hi-fi” hyped sound (eg cheaper / consumer grade gear). These characteristics are what sweeten the sound and make casual listening a more pleasurable experience.

It may seem like a paradox then, that more expensive studio monitor speakers and, to a certain extent, headphones aim for a flatter, more “sterile” response that tries to suck out any hype or excitement from the frequency range. But that’s exactly what studio-grade gear is supposed to do: By keeping these biases and frequency bumps to a minimum, studio engineers and producers are able to hear an accurate representation of the sound coming out of their DAW. Generally, the more expensive you go, the flatter the response though there is no totally flat playback system – at least not one that doesn’t cost thousands of dollars set in a room costing even more.

Sonarworks Reference 4 aims to disrupt all of that: for a couple of hundred dollars, the app claims to flatten the frequency response of headphones and speakers that are compatible with it. The way it works is the app first creates a profile of a specific headphone. By measure and mapping out its characteristics, Sonarworks is then able to determine the peaks and dips in the frequency response of a particular model, and it then applies the correction within the software. The result in theory is a flatter sounding headphone.

You can also use Sonarworks Reference 4 with your speaker monitors, though you’ll need to purchase the Studio Edition plus a measurement microphone because you’ll be doing the monitor profiling yourself.

If you want to use it with your speaker monitors, you’ll need to create a profile for them yourself using Sonarworks Reference 4 plus a measurement microphone available directly from Sonarworks (a US$69 purchase). The reason for this is because the app also measures how your speakers interact with the room that they’re in, so you need to do the measuring yourself.

In Use

It works as a plugin in your DAW and as a “sitewide” application – this lets you listen to reference tracks outside of your DAW which can be handy during the mixing process as you listen to other songs to compare how your mix sounds, though you may want to turn it off when you’re casually listening to music as it essentially strips the biases and characteristics of your playback system.

I added the Sonarworks Reference 4 plugin to the Master bus of my Ableton Live project (you need to insert it after all of your processing in the Master channel). Once inserted, you then open the plugin and choose your headphone from a dropdown list. Once selected, you can then enable or disable the frequency correction.

The result is immediate, apparent and eye-opening. Switching the correction on removes the bass and high-end sparkle of my Audio Technica headphones – I now hear a less-exciting, flatter and duller sound. I also hear more of the mids now, like they’re on the same level as the lows and highs. It’s a bit off-putting at the start and you’ll want to bypass the correction to get back to the “good” sound of your headphones, but this is exactly what Sonarworks Reference 4 is meant to do. By turning the correction on, you’re now hearing your production without any of the “sweetness” or “warmth” added by your choice of headphones, and you’re left with the rather-naked feeling of hearing your music without adulterations.

The good news is that this flatter sonic representation allows you to make more informed critical listening decisions without having to deal with the built-in biases and characteristics of your headphones or speakers. If your cans have a bias towards the low end, for example, you may realise that your production doesn’t have enough bass when you play it back on other systems like your car or through a different pair of speakers or headphones. The reverse is also true: if your speakers are brighter and lacking in low end, you may end up mixing in too much bass to the point that it sounds “woolly” when you listen on other systems.

Sonarworks Reference 4 helps in this regard through its correction algorithm, though there are limitations: if your headphones are just about decent and usable (ie the entry-level models in Sonarworks’ list) don’t expect them to sound as good as models that cost thousands of dollars (eg the Sennehiser HD-800). Sonarworks Reference 4 just calibrates and flattens the frequency response of your headphones or speakers, it doesn’t magically turn a cheap pair of speakers into an audiophile grade system that costs as much as your college loan.

That said, the flattening does allow you to get the most out of your existing (compatible) headphones or speakers, so that in itself should be reason enough for DJ/producers who are starting to get serious with their production and mixing, especially if they don’t have access to more expensive gear or a treated room.

The good news here though is that it makes bad or underwhelming headphones (eg the Blue Mo-Fi) usable, if only for production tasks or as an alternate playback system when checking your mix. Another advantage is you’re able to produce when you’re not in front of studio speakers and you have to use headphones – while the sound quality and sound stating of headphones and monitor speakers are different, you at least get to work with that “flat” frequency response when producing with cans.


Sonarworks Reference 4 is a great idea in theory, and in practice it is able to make the frequency corrections, lessening the bias and characteristics in favour of a more neutral sound. The result is that the app makes it easier to hear and tweak nuances in your mix using your existing playback system. The only downside is that it doesn’t cover a lot of headphones meant for DJing – there are a few (it does have the Pioneer DJ HDJ-500 and the Sennheiser HD-25) but it needs updating as there are many new headphone models available today.

If you’re aiming to get started producing music and would like to pick up a pair of headphones, Sonarworks 4 is a great companion app – we recommend picking up something like the Audio Technica ATH-M40x or ATH-M50x, both of which are in Sonarworks’ list of compatible headphones. Adding in the measurement microphone and getting Reference 4 Studio Edition also means that you can calibrate your speaker monitors, and this extends the usability of the app, especially since it works with just about any kind of speaker system.

Overall, it’s a fantastic tool to eke out the most from your headphones or monitor system. Just adjust your expectations – in other words, don’t expect it to turn a cheap pair of headphones into one that costs thousands of dollars.

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