Sonarworks Reference 4 Headphone Edition Review Page 2

So that’s how it works – how does it sound?

Well, if you like something in the neighborhood of the Harman Curve, very nice. I have been sorting through some other headphone correction tools, and I must say that the Sonarworks system is surprisingly transparent. Most consumer-oriented processing exhibits audible artifacts and colorations to the sound, but Sonarworks pro-oriented software is about as artifact-free as I’ve heard. The correction for my Beyerdynamic DT880’s was spot on, taking them from thin and overly bright to very natural and much fuller sounding. Major 8-10khz problem spots, sucked-out mids and rolled-off bass response were very well sorted out, yet without the processing artifacts often introduced by other consumer-oriented EQ’s. I’ve always appreciated the DT880’s for their ability to convey tons of depth, and attempts to EQ them often kill that wonderful stage depth. Here I felt the DT880’s had greater stage depth than I’ve ever heard from them. Likewise on my Sennheisers, Meze’s, Bose and other headphones, the positive qualities seemed to come forward, drawing my attention to the way the headphone presented transients or imaged and letting me compare their unique ‘personalities’ with the common ground of a similar frequency response.

Some of the headphones seemed to handle the EQ better than others however. The Beyerdynamic and various Sennheiser headphones, for example, could only be bass-boosted so far before the low-end started bleeding into the mids. The equalization also never changed the inherent character of the headphones: the HD800 and DT880 will never be as tight and punchy in the bass as an Audeze say, and no amount of my fiddling with the Sonarworks software could change the softer bass characteristics of these headphones. Past 3db of boost I stopped perceiving much additional bass, and instead got an unappealing tubbiness in the lower midrange and mid-bass.

Likewise, the Meze headphones have a cup-resonance in the midrange which can make them a bit honky and colored sounding in the 500hz region. The Sonarworks EQ did a lot to smooth this over and make it more linear, but the issues were still perceptible as a kind of odd transient lifelessness in the 100 - 1000hz range. I also had a few issues with the Sonarworks software turning up sub-40hz bass a little higher than was optimal for some headphones – I’m not sure if this is the related to the response curve I mentioned earlier, some headphone’s inability to be equalized past a certain point or a combination of factors, but the included gentle-tilt filter included was very helpful in this instance.

In general, the more linear a headphone was to begin with, the better it took to the Sonarworks EQ. While this may seem obvious, the point is that the Sonarworks software, while more effective than any correction methods I’ve used previously, cannot make a bad headphone into a good one. It can correct poor tonal response, which certainly helps a lot and can, in some cases, increase the perception of transparency. But it does not actually increase detail retrieval, transient slam, or a clean dynamic response.

Sonarworks screen shot

That said, I did find the software most effective and compelling on inexpensive and very-expensive headphones. My reasoning is that it makes inexpensive headphones, where the largest gains in sound quality are made by any alterations, much more listenable. For expensive headphones, dynamics, transparency and detail retrieval are usually excellent, but frequency response can be just as bad, if not worse, as less expensive headphones in my experience. Here, the aforementioned abilities of these headphones can shine and be appreciated even more when their annoying flaws are corrected.

An additional option here is the choice between minimum-phase and linear-phase filter types. These will be familiar to most audio engineers, but the basic premise is that minimum-phase filters cause phase-shift and are capable of less precise but lower-latency frequency correction, while linear-phase filters are capable of much more precise filtering, but cause higher latency, and pre-ringing noise before the transient impulse.

Latency isn’t an issue for most consumers outside home theatre applications, and even though the Sonarworks software declared a relatively high 22ms and 67.33ms for the minimum phase and linear phase filters respectively, I had little issue using the program while gaming or watching movies. The buffer is also adjustable from 32 to 2048 samples as well, which can help alleviate system-specific issues you may experience.

In general the sonic differences between the two filters are fairly typical for what you’ll find in filters of these types. The minimum-phase filter has a natural transient and soundstage presentation but at the cost of true accuracy – depending on the amount of frequency correction used, time/phase and soundstage issues can range from negligible, to ‘slightly smeary,’ to ‘smothered across the stereo field like butter and toothpaste.’

By contrast the linear-phase filter has a much smoother sound because it is able to do much finer levels of correction than minimum phase filters. It also does not exhibit phase shift, and exhibits none of the soundstage issues of minimum-phase filters. All this comes at a cost however – the transient pre-ringing causes a sort of processed-digital sound in the treble, a kind of clinical sheen and a softening of the treble, this effect is made worse the more you boost or cut the bass.

Your preference will depend on the kind of music you listen to, and I found that many newer, popular recordings which sound a bit harsh already and have very little stereo information of interest sounded much better with the minimum phase filter, while warmer, older recordings that are a noisier or softer tended to compliment the sound of the linear phase filter. Ultimately the choice is yours and will depend on your preference, though I suspect most home consumers will prefer the minimum-phase filter, especially on headphones.

One of the major downsides of the Sonarworks software is that if you have modded headphones or headphones that are not part of Sonarworks’ library of measured headphones, this software is of little use to you. The catalog of headphones was quite extensive, covering many popular brands and past catalogues such as Sennheiser, Sony, V-Moda, etc. as well as current headphones such as the Focal Clear and Elear. That said, much of the headphone selection is targeted towards professionals, and there is a wealth of inexpensive headphones, but some conspicuous absences for the high-end headphone enthusiast. There are only two Audeze headphones, the LCD-X and LCD-2 with no indication of what revision, no Focal Utopia, Mr. Speakers headphones, no electrostatic headphones, ZMF, etc. In that sense, the software is a little more egalitarian in scope – for the 99-Euro price point, I would not hesitate to recommend this software to anyone interested in improving the frequency response of their headphones. I should also mention that Sonarworks is constantly updating their list of supported headphones, and that list, as well as a form requesting the addition of other headphones may be found here.

In conclusion, I believe I’ll be using this software quite a bit more both in professional mixing and mastering life, and in my audiophile life. With a little tweaking this is a product that can make a very noticeable and worthwhile improvement in the frequency response of your system. Just make sure you own or request a supported headphone before you buy it.

Sonarworks SIA Smerla iela 3 Riga, LV-1006 Latvia

buckchester's picture

Great review. I tried Sonarworks with a pair of Hifiman HE-400i and I found it improved the sound quite a bit. However, I felt like it boosted the bass a little too much and it added a subtle sort of “shouty” quality to the sound, which I believe lies somewhere in mid range between 1khz and 5khz.

I’ve since bought a MiniDSP EARS and MiniDSP HA-DSP, which by the way, I’m able to get even better sound with. With these, I have been able to significantly improve the sound quality of the following headphones: Audio Technica M50x, Hifiman HE-400i, and Focal Elex.

After measuring the 400i headphones with the EARS, the bass response I measured is quite close to most other measurements of out there (quite close to those SBAF, actually). Sonarworks measurements of these headphones show a very steep roll-off in the bass starting around 100hz, however, most other measurements, including mine, show a much narrower roll-off in this region. When I measure these headphones with the Sonarworks curve engaged, it shows a massive (~+12db above neutral) bump in the 40hz region. As a result of their measurements, I believe they have over-compensated in this area with these headphones. I wonder if those that they measured had worn out earn pads, which can apparently cause the bass to roll-off more steeply due to a flimsier fit. I found their bass measurements of the Audio Technica M50x and the Focal Clear Professional (closest they have to the Elex) seem closer to what I get with the EARS.

I cannot hear a difference between the filters.

Skycyclepilot's picture

I used Equalizer APO, a peak filter in that program, and a Voxengo graphic equalizer VST (hosted by Equalizer APO) to match my DT 1990s to the FR curves published by and DIY Audio Heaven with excellent results. All Beyer headphones have a sharp peak at about 8 KHz, thus the peak filter. The 1990s are overly warm, thus the equalizer. If you're willing to invest the time, this method is free.

echoplex's picture

Thank you for the review. It's unclear to me from looking at the screenshot of the software how you would get Sonarworks 4 to equalize the headphones to reproduce the Harmon Curve. Clearly, Sonarwoarks could have added a target curve for this, but it appears they did not. While I have no doubt that equalizing to a flat response will improve the sound of inexpensive headphones, the idea of taking a headphone that is already well designed to match the Harmon Curve - and then forcing it to flat response - makes no sense technically if you want you mixes to sound the same in headphones as they do in a well treated room (which is what audio professionals would be doing). This would not be a flaw in the Sonarworks design *unless* they are really reproducing the Harmon curve when they picture "flat" response on the graph.

I have never used the mini-DSP boxes, but you should also look into the software measurement application and plugins in IK Multimedia's Arc 2.5 system (cones with a different kind of design for a measurement mic). ARC predates Sonarworks and uses the Audyssey MultEQ® XT32 correction software found in some surround sound units.

Then at a more sophisticated level of acoustical correction (and cost), is the Dirac room correction software, and Trinnov correction (only available in hardware) which many pro audio people use depending if they want a software or hardware solution.

Slawomir's picture

In my opinion equalization of headphones should be based on measurement without(with subtracted) Harman Curve because human ear create resonances causing bump in 3khz region and headphones actually don't cause this phenomenon. Engineers from Sonarworks could and should equalize headphones to target without Harman Curve if they're using dummy head with ear canal.