Ridding the World of Bad Sound
15 Minutes with Dirac Founder Mathias JohanssonMathias Johansson, CEO and co-founder of Sweden’s Dirac Research, has devoted his professional life to developing technologies that improve sound quality—whether that sound is music heard over headphones or car speakers, or an intricate Dolby Atmos soundtrack played over a high-end home theater system. “Our passion is to invent new sound technologies that offer a better sound experience regardless of the sound system,” he says. “We want to be a quality seal for good sound, and we want to achieve this through scientific methods.” If the accolades the Dirac Live room-correction system has garnered among enthusiasts is any measure, Johansson is not only on the right path to elevating sound quality but making tangible progress.
S&V: Tell us a little about your background and the history of Dirac Research.
Mathias Johansson: Dirac was founded as a spin-off from [Sweden’s] Uppsala University in 2001. We were six researchers who had developed a technology for improving the sound experience from loudspeakers by digitally optimizing the loudspeaker’s frequency response and its impulse response. Our first customer was BMW back in 2004 and, since then, we have expanded our optimization capability to include almost all types of sound systems, including earphones, loudspeakers, professional sound systems, mobile phones, and portable speakers.
S&V: I’m told there’s an interesting story behind the company name. Can you share it?
MJ: One of our unique inventions was an optimization of a sound system’s impulse response, which describes how the system reproduces transients such as percussion. A loudspeaker, being a mechanical system, has a certain settling time, which means transients get smeared out by the loudspeaker. The impulse response shows this “time smearing” in detail, and by optimizing it we get closer to an ideal impulse response which means an infinitely short settling time. Within mathematics, this ideal response is known as a Dirac impulse. Paul Dirac was a British Nobel-prize winning physicist, and we named our company after him.
S&V: How has the company mission changed over the years and what’s your focus today?
MJ: From day one, it’s been our company mission to realize the full potential of any sound system. While our reach has broadened, and we now focus on many more categories, our mission remains the same. The Dirac team is one of music lovers, and thus our passion is to invent new sound technologies that offer a better sound experience regardless of the sound system used. We want to be a quality seal for good sound, and we want to achieve this through scientific methods—as opposed to through marketing or branding, alone.
We want to be a quality seal for good sound, and we want to achieve this through scientific methods—as opposed to through marketing or branding, alone.S&V: Dirac offers a number of technologies for car, portable, and home applications. Among them is Dirac Live—the one with which Sound & Vision readers are probably most familiar. Before we delve into Live, can you provide highlights of the key technologies in your portfolio?
MJ: Sure. Let’s walk through them, starting with Dirac HD Sound, which deals with impulse and frequency response optimization of earphones and speakers.
Dirac Power Sound is dynamics processing and nonlinear processing for small speakers, such as mobile phone or tablet speakers. It brings out louder and clearer sound and more bass, all without causing any distortion. The mobile market also uses Dirac HD Sound.
Dirac Panorama Sound, for arrays of speakers with two or more drivers, extends the sound image and stage well beyond the physical limits of the speaker. It’s intended for use with small soundbars or portable speakers, laptops, tablets, and mobile devices.
Dirac Unison is the next step in digital room correction. It uses multiple speakers to support the main speakers and thereby not only optimizes the impulse response and frequency response to a greater extent than any other room-correction technology optimizing just one speaker at a time, but it also minimizes sound variations across the listening space. We call it active room treatment, and it is used in the B&W sound system from Volvo that was just named Best Car Audio System – Cars over £25,000 at Car Tech Awards.
Dirac Room Calibration is a simplified version of Dirac Live that runs on smartphones and is targeted at Wi-Fi speakers. The focus is maximum user friendliness, to allow for a quality room/speaker calibration with a minimum of user input.
Dirac Sensaround creates sound field extension, room simulation, and cross-feed for earphones.
Dirac VR is a new approach to positional audio over headphones using head-tracking, targeting high-end sound applications.
While we have a few additional technologies mainly used by the automotive market, these are our main products.
S&V: Which of these technologies is most widely available?
MJ: For hi-fi enthusiasts, the Dirac Live technology is most widely available. Dirac Live is used in cinemas, studios, and hi-fi applications. By strongly reducing the coloration that the listening room and speakers themselves impart on the sound, Dirac Live brings about a truer-to-the-source sound reproduction.
In general, the most widely adopted technology of ours is Dirac HD Sound, which is used in millions of smartphones to optimize the sound experience from headphones. Even rather inexpensive earphones have a substantial hidden potential that can only be realized by tuning them with digital signal processing. Most headphones color the sound quite badly, but the physical potential of the transducer is such that it lends itself very well to digital optimization.
In fact, many professional headphone reviewers deem that the out-of-the-box headphone model that’s shipped with the mobile device—that are first measured and then tuned using Dirac’s high-resolution frequency response and impulse response correction—actually outperform expensive, high-end headphones.
S&V: Back to Dirac Live, the speaker set-up/room-correction system available in audio gear from Arcam, Emotiva, Oppo, Pioneer, Theta Digital, and others. What does it do and what separates it from other top-tier room-calibration systems?
MJ: Dirac Live does two things: It optimizes the frequency response of the loudspeaker/room combination, while also improving its impulse response. By strongly reducing the coloration that the listening room and speakers themselves impart on the sound, Dirac Live brings about a truer-to-the-source sound reproduction. A few other things are noteworthy about its performance:
First, you simply can’t rely on guessing when you are creating a high-end room/speaker optimization system. Since room acoustics vary substantially over frequency and the position in the room, you simply have to take multiple measurements for the algorithms to work with data, rather than rely on few measurements and assumptions. The room response varies enormously even just by moving your microphone a few inches. That said, I can’t stress enough the importance of a good measurement routine! It’s imperative to capturing all relevant room acoustic information about your particular loudspeaker/room set-up. We recommend using nine measurement positions, spread out over the listening area, in addition to just beyond. This way, you have the basis for any algorithm to do a good job.