CES 2018 Show Highlight: Sonarworks Headphone Correction Equalizing Software

I got the call a couple weeks before CES. A familiar Public Relations firm wanted me to meet up with a new client. I resisted initially...too many scheduled meeting can get in the way of an efficient route traveling the acres of CES show floor. "But," the rep said, "it's Sonarworks, the folks that do headphone compensation, and they want to meet you." Ahhhh, I know of them and am curious. Compensating headphones is tricky business; I would like to hear their story. I arranged a fairly early morning meeting so as not to impede my daily routine...and boy am I glad I did.

Helmut Blems, CEO, and Janis Spogis, VP Products, were engaging and competent spokesmen for the Sonarworks products, able to clearly understand and directly address my technical questions...until they wouldn't. There's quite a lot of proprietary technology they've invented to perform the difficult task of compensating headphones and as I tried to drill into the details there was only so far I could go before company secrets closed the door. None the less, it was quite obvious they knew what they were talking about, and what they knew was some pretty delicious secret sauce.

Sonarworks has a suite of tools for professional recording studios to equalize their studio monitors. Helmut went into detail about some of their measurement techniques and the data produced. They're able to produce acoustic maps of control rooms and provide users with a powerful set of room tunings that permit the engineer to create a very tight sweet spot while working, and then switch to another room tuning to produce a sweet spot at the couch behind the engineer for producers and artists to hear the mix. Very cool stuff, you can check it out here.

No surprise, with numerous successful studio tweaks under their belt, recording professionals started asking if they could do similar things for studio headphones. They started looking into it...no surprise, they found out it was a lot harder than they expected. When I told them I felt EQing headphones was at least four times harder than EQing speakers they both nodded their heads in agreement. None the less, they persisted.

Though they wouldn't go into detail, they've found a way to transfer their understanding of neutral on speakers to headphones. They do have at least four measurement systems to acquire data for over-ear, on-ear, in-ear, and intra-conchal (ear-bud) headphones. They've taken may thousands of headphone measurements, and currently have compensation curves for 117 headphones.

Their True-Fi headphone compensation software ($79) is available as a plug-in for a variety of digital audio workstations and full-featured music playback software, but they also have versions that get installed on MAC or PC computers that inserts itself deeply into the audio playback system to allow compensated playback from any audio source. They will also soon be shipping apps for both iOS and Android playback, which will be included with your $79 purchase when available. My understanding is that he $79 price also includes all current and future headphone compensation curves developed.

The proof is in the pudding though, so they gave me a little demo. They played the same track on a cellphone driving a Marshall Monitor headphone (an abysmal sounding headphone) and from a laptop driving a Sennheiser HD 650 through an outboard DAC. Both were compensated. I switched back and forth listening for tonal differences. It was a very weird experience. Both headphones sounded very similar tonally...but there were differences in imaging, dynamics, and resolve. Then the compensation was turned off. OMG, the Marshalls sounded bad, and while the HD 650 returned to a familiar sound signature, it was indeed less neutral to my ears.

Needless to say I didn't leave without a request to sample the software...and have already received a promo code to download the full product. This should be fun!

Helmuts and Janis give you the full rundown in the video.

View on YouTube here.

--------------'s picture

They're being secretive about their business because what they are doing is surprisingly simple and probably isn't worth $80 to most people:
1) measure 5 headphones
2) average their FR
3) equalize it to what's probably the Harman curve or a slight variation (if they had made a scientific breakthrough in this field of research, it wouldn't be a secret)
4) add the EQ profile to the software that people can buy with their hard earned money
The exact same result can be had with any freely available equalizer such as Equalizer APO. They refuse to publish their measurements since it would make the process of creating an EQ profile an easy task in case the headphone model hasn't been measured by a credible site like InnerFidelity, which is mostly limited to one measurement per headphone.

steaxauce's picture

There seems to be more to creating a good compensation profile than this. Maybe the ideal target depends on the style of headphones being used? In any case, I've tried inverting the measurements provided by Tyll and other sources with poor results, and different resulting tonal balances with different headphones. On the other hand, in my experience, Sonarworks provides pretty consistent results across different headphones.

--------------'s picture

Full-sized headphones and IEMs have different target curves. Different full-sized headphones do not.
The Sonarworks EQ settings should provide a better result if the unit to unit variation in a model is moderate or high. A single measurement should be enough if the quality control is good like with HD 800 and the high end Focal models. It brings me back to my original point that Sonarworks don't want to release the measurements because it would make it easier for people to equalize their headphones by themselves. More information = better EQ.
I'd be willing to take a look at your EQ profiles if you still got them around. There could be room for improvement.

mnaganov's picture

There are 30-day trials for both TrueFi and Reference 4. Since Reference can work as a VST / AU plugin, it's trivial to capture its transfer function (assuming it's linear) using e.g. Audacity, I've done that. Comparing to how you can equalize for the same headphone model using Toneboosters Morphit, Sonarworks indeed uses their own variation of Harman TC.

skris88's picture

Re "...inverting the measurements provided by Tyll and other sources", I HAVE tried inverting the measurements as provided by Tyll. And I've had EXCELLENT results. ;-)

Like Tylls says so right here, "....both headphones sounded very similar tonally - but there were differences in imaging, dynamics, and resolve".

If you're expecting EQ to be the miracle worker, you're expecting too much.

As they say, "You can't make a silk purse out of a pig's ear."

But with a study of the frequency response graphs and EQ I've made $60 Superlux HD668Bs sound "good" compared against $400 Sennheiser HD-650s. Instead of 'terrible" (they're very forward and shrill unEQed) they're "okay". Good enough to take on the rough and tumble of a road trip than the venerable HD-650s (or my now HiFiMAN HE4XXs) and still be able to enjoy my music than cringe.

I'm looking forward to this software - but USD $80 really is a little too much (my own EQ method might be just as good). :-)

raymondbl's picture

I'd say that's a bit unfair. If you do a free trial of the Sonarworks software, you could go through every calibration profile and take pictures of the frequency response, so they're not exactly hiding the EQ curve. As an experiment, you could put the curve in Equalizer APO and see if you can hear the difference.

I'm pretty sure there's more to it than just applying a frequency response curve. Their software shows you not only frequency response, but phase response. They provide three filter types, "linear phase," "optimum", and "zero latency." The FR curve they apply for each of the filters is different, and the phase response is different for each filter as well.

--------------'s picture

I've tried doing that months ago. I got an error message which told me my trial had expired despite the fact that I had never the software before. I contacted Sonarworks about my issue but never got a reply. So from my point of view, they are hidden.
I'd be willing to recreate all the EQ profiles in Equalizer APO if you or someone else could send me screenshots of the Sonarworks EQ profiles though.
A listening test would have to be a double-blind test. Sighted listening test don't provide credible results.

Headphones are minimum phase devices. The phase response is tied to the frequency response and vice versa.

mnaganov's picture

That's pretty easy:

"zero latency" mode is implemented using a recursive (IIR) filter; has the lowest latency, but introduces the most phase shifts.

"linear phase" is linear phase non-recursive filter (FIR) which indeed doesn't change the phase, but has the longest processing time (and introduces pre-ringing, but it's been told that it's unaudible);

"optimum" is a minimum phase FIR—less taps, thus less delay, but introduces some phase shifts.

All those filter types try to approximate the same FR compensation curve. And it's only the limitations of each approach that causes a bit different result to be produced.

RudeWolf's picture

0)Invent a headphone measurement routine which provides consistently neutral sounding correction curves for all types of headphones

It's not hard to draw lines with sweeps.

Bern L.'s picture

IMO Sonarworks saved the HD800 for me. I had tried (using EQ APO) and Tyll's FR graph to fix it on my own, but I never was happy with the results.

I am using SW reference 3....the biggest improvement for the least amount of money spent so far with headphones.

The only thing I would ask is that SOMEHOW a U.S. address could be used to ship headphones back and forth to Latvia. This has stopped me from custom calibrating.


--------------'s picture

I've heard the result of equalization. I wouldn't use my headphones without it.

I'm sorry to hear you couldn't get a satisfactory result with APO, because it is totally doable. As a matter of fact, I've been able to clone SW's HD 800 EQ profile with high accuracy.
The config file can be downloaded from here: https://mega.nz/#!Y1h2hR7A!Sr3Lz_jLGQD06lZNad3k7ynsoVIlAcf9HKLvQCO1BVc
Or if you can't get the file to work, the bands are listed here: https://pastebin.com/JSTsqJ2a

Proof of accuracy
Peace graph window: https://s14.postimg.org/5s3vi3sa7/HD_800_SW_APO_graph.png
The same graph superimposed in the inverted SW graph: https://s14.postimg.org/wpxsjuscx/HD_800_SW2.png
And again directly on top of the SW calibration profile: https://s14.postimg.org/iw9fuss1t/HD_800_SW.png
Apologies for the white pixelation around the Peace graphs.


--------------'s picture

I've heard the result of equalization. I wouldn't use my headphones without it.

I'm sorry to hear you couldn't get a satisfactory result with APO, because it is totally doable. As a matter of fact, I've been able to clone SW's HD 800 EQ profile with high accuracy.
The config file can be downloaded from here: https://mega.nz/#!Y1h2hR7A!Sr3Lz_jLGQD06lZNad3k7ynsoVIlAcf9HKLvQCO1BVc
Or if you can't get the file to work, the bands are listed here: https://pastebin.com/JSTsqJ2a

Proof of accuracy
Peace graph window: https://s14.postimg.org/5s3vi3sa7/HD_800_SW_APO_graph.png
The same graph superimposed in the inverted SW graph: https://s14.postimg.org/wpxsjuscx/HD_800_SW2.png
And again directly on top of the SW calibration profile: https://s14.postimg.org/iw9fuss1t/HD_800_SW.png
Apologies for the white pixelation around the Peace graphs.


Bern L.'s picture

First...apologies for being snippy. I wanted to edit after posting but I couldn't.

I agree with your assessment of EQ/APO being a great and easy program to use. Especially with the Peace GUI addition. I just couldn't quite get it to where I was content. I will give your settings a listen. Thanks.


bon's picture

How did you clone the freq curve to such incredible accuracy? Mind giving me some instructions. What technique did you use? How did you get all those values in the txt file? That is the file you use in eq APO, right?

--------------'s picture

I made use of basic photo editing skills and trial and error. No fancy programs or scripts.

Sonarworks doesn't directly show the equalization it is applying, but rather how the headphones measure after their compensation curve has been applied. So the first thing you want to do is flip the EQ profile on it's head - this can be done in MS Paint. Now you got what the equalization looks like.
The next thing I did was opening up Equalizer APO + Peace GUI and made a draft for my EQ profile by eyeballing Sonarworks' profile. I then took a screenshot of the Peace graph window, opened it in paint.net (this is a photo editing program, not a website) and singled out the graph from the rest of the graph window with the Magic Wand tool. Open a new project, copy paste the graph into it and save it as a .png file to ensure a transparent background.
I moved on to another piece of software called FastStone Photo Resizer to resize the Peace graph image to a size that fits Sonarworks' graph window of the HD 800. The height of the Sonarworks HD 800 EQ is 123 pixels. While it takes up the full width of the window, the Peace graph cuts off slightly before, so the width had to be 623 pixels.
So we now have a resized Peace graph that can be placed directly on top of the Sonarworks graph for easy comparison. Everywhere the graphs didn't line up, I corrected my EQ settings and created a new comparison image. Repeat until the result is satisfactory.

I got the values into the Pastebin simply by looking at my EQ settings and typing the same thing into Pastebin. They can also be exported as an .xml-document, but it looks a bit messy.
The file contains the same values as the Pastebin and can be loaded directly into Peace by placing it in X:\Program Files\EqualizerAPO\config.

bon's picture

That must have took ages. Still very impressive that you did it with such accuracy. I have M50x. I'll give it a try when I get time. There is a discord tool that matches the freq curves of two headphones. Maybe I will try that to get the freq curve of HD800 and then add your values to that file. Anyway, if you got any suggestions for the eq of M50x, please Let me know. The freq curves measured by innerfidelity and sonarworks are very different. Which one do you think I should go for? M50x are very decent sounding but are somewhat harsh for me in higher vocal region. Sometimes it sounds like scratching glass at certain instances for some songs. Other than that no regrets.

--------------'s picture

Took about 40 minutes to get it within a 0.5 dB error margin and another 40-50 minutes to sort out the remaining minor deviations.
IF and SW use different compensation curves, so the graphs can't be easily compared. IF thankfully displays the uncompensated measurements, so that's extremely useful when equalizing. SW have neither published their compensation curve nor uncompensated measurements.
I'll recommend that you EQ them to the Harman target curve. Looking at measurements, I think it's hard to explain exactly why you sometimes find vocals harsh sounding. M50x lack a bit of energy in the lower mids and also have a small treble spike around 4.1 kHz, but that alone can't explain it. Could be that you got a pair with more treble than the average, you are more sensitive to treble (keep in mind compensation curves are built around the average person) or that you are just listening to bad recordings. You can try to single out the potential treble spikes in the upper treble by running SineGen: http://sinegen.en.lo4d.com/download

Anders's picture

I uninstalled Boom 2 from my Mac. I found after several adjustments that I preferred my Focal Elears as they are. The necessary boost in the higher frequencies ended up being tiring, so I reduced it, basically getting back to the sound signature that I have. Alas, nothing gained.

Downloaded Sonarworks' program, and it appears from a quick try to be much better. These are my observations (having my Elears directly attached to my iMac):

( ) Without the True-Fi enabled the Elears appear muffled.
( ) The soundstage is wider and the sound is more forward leaning.
( ) The balance is better.
( ) The "Adjustment for Age" works well giving a good boost in the higher frequencies.
( ) The user interface is easier to work with than Boom.

I would suggest that you try it out - there is a 10-day free trial period.


steaxauce's picture

It's about time you discovered these guys! I've been using Sonarworks for years and consider it to be an essential part of my listening configuration. I'm hooked.

The results are excellent with the HD800. I'd spend the money to upgrade to a new flagship in a second if a headphone ever came along that I was confident would give me better sound post-calibration than the HD800, but it's hard to tell, since reviewers (rightly) tend to focus on the tonal balance of headphones. But tonal balance doesn't matter much when using calibration.

I did buy an LCD4 at one point, but the HD800 with SW (SW800?) smoked it. It wasn't close at all. Until some trustworthy people (like Tyll) start reviewing headphones with Sonarworks and tell me otherwise, I'm inclined to think that switching to one of the other flagships from Audeze, Focal, etc. would lose me the HD800's great imaging without giving me much else in return.

Tyll, you should really give Sonarworks a serious look. The WoF might end up looking pretty different. :D

mtmercer's picture

I've used Sonarworks Reference 4 Systemwide for calibration with several headphones I have. Like steaxauce, I am hooked. HD800, unlistenable to me stock. HD800 with Sonarworks... Whammy! Focal Elears... Ditto!

My Sonarworks Sleeper is the Sony MDR-7506. That headphone is mindbogglingly good with the Sonarworks calibration.

It doesn't work for everything. The Phillips SHP9500 sounds pretty bad once calibrated due to the bass distortion.

Tyll - If you are taking requests, I wonder how the Elear with the Sonarworks Reference 4 profile (I vote linear phase filter) compares with the stock Focal Clear.

gzost's picture

Are you using the default or a custom calibration for the MDR 7506? With the Fostex TH-x00 I was surprised how much the custom calibration differed from the default curve. I'm curious how Sony are doing regarding consistency in production.

mtmercer's picture

Regarding Sony's consistency in production, I only have one pair so I can't comment one way or the other.

Regarding which calibration I use, I basically do the same thing for all the headphones I have that have average Sonarworks calibrations which is: Start out with the average flat calibration in Reference 4 systemwide. Then, I use the tilt feature to tilt the frequency response to whatever I prefer for whatever I am listening to for whichever headphone I am wearing. I'm pretty sure the tilt feature is only available in the Reference 4 plug in and Reference 4 Systemwide, not True-fi. Note I listen to music and use Sonarworks for personal enjoyment. I do not do any mixing or mastering.

metal571's picture

Including measurements of headphones that are currently running Sonarworks profiles in future reviews would be really interesting. Could have 3 measurements per headphone - one with EQ "to taste" or "by ear", one with Sonarworks, and one uncorrected. EQ is a very useful review tool - I tend to use it as part of identifying differences in grain/detail/THD and soundstage between headphones as that is most of the difference left after calibration via EQ. I was starting to wonder if anybody would ever come up with a system like this, so it's very interesting to see it come to life. Bravo to these guys, really cool stuff. I'm sure the upcoming InnerFidelity graph tool will have an EQ generator based on user preferred FR as well, right? Right? :P

Roberson's picture

Thanks to the author for the article! Very pleased!
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stevensalbert's picture
jpelg's picture

Seems like an effective product that works as designed, with good support, at a very reasonable price. I look forward to trying the mobile version.

detlev24's picture

...can be found in the comment section of Bob Katz's last blog entry:

https://www.innerfidelity.com/comment/515270#comment-515270 and following.

Enjoy! :)

GumbyDammit223's picture

I am using their plugin and Foobar 2k with my HD700's and couldn't be happier. The sound just seems "fuller" now when the plugin is enabled. I initially had a bear of a time getting it to run on my computer but Mattis with their customer service group spent MUCH time with me and MANY emails getting it working. I haven't purchased v4 yet but will probably do so this weekend.

wiinippongamer's picture

Without personalized HRTF, this is a mere parametric EQ for dumb people.

gzost's picture

Assuming that True-Fi does nothing more than what can be done using e.g. Equalizer APO - why is this an offer for dumb people? From my experience so far I get great improvements for any of the supported headphones I own, all from an easy-to-use interface. These improvements are well worth the price of the app for me. Maybe I could create the same effect with hours of listening to test tones and fiddling with equalizer settings. For some people, such as apparently yourself, that is fun - and I'm honestly glad for you. Myself, I don't want to dive into this part of the hobby and am glad that somebody offers this as a service, allowing me to spend my time listening to music instead.