Choosing a headphone can be overwhelming. There are innumerable shapes, sizes, and sound signatures, at prices ranging from pocket change to a small fortune — how can we know what headphones are truly “good?” Reviewers (us included) can only provide subjective impressions, and searching for objective measurements of sound signature and quality can be a fool’s errand — measurements often differ between even the most experienced reviewers, and even the most expensive measurement equipment is prone to user error and variations in test conditions. Manufacturers promise that their headphones sound like “what the artist intended,” but that too is nearly impossible — most audio equipment colors the sound being played in some way; we cannot know what equipment the artist used during recording, and the artist cannot know what equipment we’re using to listen. In this mess of audio anxiety, a Latvian audio technology company Sonarworks is taking a new approach with its True-Fi software.
Sonarworks’ True-Fi app is currently compatible with macOS and PC — a mobile version is in development — and uses digital signal processing (DSP) to alter the sound signature of headphones to a “reference” sound. This begs the question: what does Sonarworks consider “reference?” When we met the company at CES, Sonarworks told us that they use a combination of sensible methods: they surveyed musicians and mastering engineers about the equipment they use when creating music and what they consider a “reference” sound, then measured that equipment and compared it to professionally-calibrated flat-sounding speakers in treated rooms. All this information is used to create a “reference” curve to which other headphone measurements are compared. Fortunately for us, Sonarworks is doing this the hard way — rather than applying a generic compensation curve to all headphones, the company measures each headphone individually and creates a custom adjustment curve for it.
Of course, Sonarworks doesn’t own a magically perfect measuring rig, but the fact that they measure each headphone on the same rig at least ensures consistency in their results. As of this writing, over 130 headphones are supported, while it surely won’t be possible for the company to support every headphone on the market, they’ve already measured the majority of the most popular headphones on the market today.
It’s important to understand that the True-Fi app is not an equalizer. Most computers and mobile devices offer equalizer settings, but these are often limited in resolution (iTunes’ equalizer is just 10 bands) or limited to vague presets (“rock,” “bass boost,” or “small speakers”), and can easily ruin the sound by overdriving headphones, thereby causing distortion. True-Fi, by contrast, installs as its own sound playback device, inserting itself between the player (iTunes, Foobar, etc.) and the DAC, reshaping the sound before it gets converted to analog and amplified. With this method, Sonarworks’ proprietary DSP can potentially make adjustments with much finer precision than any equalizer — around 4,000 points of resolution. Still, Sonarworks doesn’t require you to accept its results blindly — users can still tweak the sound by adding age compensation adjustments (boosting treble to account for for age-related hearing loss) and bass adjustments (+/- 8 dB of adjustment below 100 hz).
We tested SonarWorks with a variety of headphones — the $60 Philips SHP9500, the $180 Beyerdynamic DT 770 Pro 80 ohm, the $250 Audio-Technica ATH-MSR7, the $1,000 Focal Elear, and the $1,400 Sennheiser HD 800.
We left the age compensation and bass adjustments turned off for all our tests. Using the app is simple — just search for the headphones you want to use, and they’re stored in a drop-down menu for quick switching. The True-Fi DSP can be instantly toggled by clicking a large button; there’s no delay or skipping to complicate the A/B testing. The True-Fi app made audible changes to each headphone’s sound signature, with no distortion that we could detect. The “reference” sound signature that True-Fi replicates is smooth, with comparatively less treble presence than the MSR7 and HD 800 (much less than the DT 770) — this is a very listenable, non-fatiguing sound signature, though with a softer edge than we generally prefer. The changes were sometimes subtle, and other times striking, even on the more expensive headphones in our test set.
Though the True-Fi app did not magically increase the quality of all headphones — the limitations of the budget SHP9500 remained even after DSP — the True-Fi app moved each headphone closer to Sonarworks’ “reference” sound signature.