Stereophile|October 2021
Adoption of DSP-based speaker-and-room correction in home theater—a parallel universe to audiophilia—is almost universal. It’s easy to understand why.

Home theater matured in the digital age. Its fans were expected to install several loudspeakers in a full-range setup that included at least one speaker—the subwoofer(s)— that functioned exclusively in the problematic bass region. Setup issues were intimidating.

Help quickly came in the form of setup utilities that required no knowledge of acoustics—only a willingness to position a microphone for a series of measurements and let the system do the rest. Audyssey was the first such utility to gain wide acceptance. Today, some arrive installed in AVRs and preamp-processors; others come as standalone devices or computer software. Most work well, providing precise level balance, compensating for unequal path length differences, and correcting in-room frequency response for all the speakers.

In the two-channel world, things have proceeded much more slowly. I can think of several reasons. There are fewer speakers to integrate. Small, stand-mount speakers often benefit from uncorrected room modes to extend their range. Stereo listeners are much more likely to integrate analog sources—turntables, reel-to-reel tape, and old-fashioned radio tuners—into their systems and to resist converting that pure analog signal to digital so that it can be processed and room-corrected. And yet, these days, most two-channel audiophiles spend at least some of their time listening to digital, whether it’s from a streaming service, locally stored downloaded or ripped files, or old-fashioned shiny silver discs. There’s a place in the two-channel world for room-correction DSP.

Dirac Live (the original)

When it first appeared, Dirac Live was a software product that the user could buy, download, and install into a Windows or Mac computer used for music playback.1 As such, its use was limited to the more intrepid and technical audio consumers. For those of us who accepted the job, it was an ear-opener. Not only was it more flexible and precise than those convenient built-in products; it was audibly more capable of dealing with problematic room effects. I reviewed the original release of the Dirac Live Correction System (DLCS) in 20142 and installed it into both my systems, for multichannel and stereo.

In its original implementation, the Dirac Audio Processor (DAP) acted as a virtual audio device, inserted into the signal chain between your music program and your DAC.


Description Dirac Live Processor for Windows or Mac. Version 1.4.0. Enables Dirac Live processing without dedicated hardware. Supported plug-in formats: AU, VST, VST3, and AAX. Dirac

Live Calibration Tool for Windows or Mac. Version 3.0.14. Includes Enhanced Phase Correction algorithm for improved stereo reproduction. Supported platforms: Windows 10, MacOS Mojave, Catalina, and Big Sur.

Price Dirac Live processor, $349 (stereo license), $499 (multichannel license). Dirac Live Calibration Tool: free. Purchase and download from live.dirac.com/download.

Manufacturer Dirac Research AB. Stationsgatan 23-25, 753 40 Uppsala, Sweden. Phone: +46 18 4108210. Web: dirac.com

The DAP accepted only PCM sources (no DSD) and, at the time of the review, only up to 24/96. The other half of DLCS, the Dirac Live Correction Tool (DLCT), was used to conduct measurements and create filters. Those filters were uploaded to the DAP, which applied them speaker by speaker to the music being played back. I loved it.

Over time, DL added support for 24/192 PCM, expanded its hardware compatibility, and introduced a VST plug-in version of the DAP. Notably missing still was bass management. It’s still missing, but not for long. (See sidebar, Dirac Live Bass Control, p.162.)

Dirac Live 3

I stayed in touch with the Dirac team. After a while, the responses to my questions and requests shifted from answers and fixes to intimations that they were directing their energy to a new product. At the 2018 Munich show, I had a long conversation with Jakob Ågren, Dirac Live’s head of product management. He intimated that all my requests would be fulfilled by a new version of Dirac Live—but they’d be directing their earliest efforts to creating an embedded app for AVRs and prepros—not computer applications. It was, I’m sure, a wise business decision, but it wasn’t what I wanted.

Dirac Live 3 is finally here, not only on many hardware platforms but, finally, as a PC and Mac application. As promised, it offers many enhancements over earlier Dirac software, with more promised.

The Dirac system still has two components: the Dirac Live Processor (DLP, formerly the DAP), which applies the filter corrections to music as it plays. In PCs and Macs, it can be installed as a plug-in or as a regular application. Plug-in support is not universal, but JRiver, Audirvana Studio, Amarra, and most DAWs support it.

Many computer-based music apps can work with the standalone Dirac Processor. The processor module appears as a virtual soundcard (limited to 8 channels) and becomes the computer’s default output device. The actual target device—the DAC—is specified in the Dirac Processor. There’s no reason why this configuration should not work with all music players and the desktop apps of streaming services, but I could not get it to work with Roon.3 I used it success-fully with JRiver, Apple Music, and Qobuz (up to 192kHz).3

A warning: The standalone application routes all sounds, including notifications, through the Dirac Processor to your system. If you don’t turn off all system sounds, you and your neighbors risk ear-popping beeps, bells, and swooshes with the arrival of each new e-mail or the insertion of a USB drive.

The second component, Dirac Live (formerly DLCT), makes all the measurements and generates the corrections. You pay for the DP: $349 for a stereo license, $499 for multichannel. DL is a free download.

Up and running

Dirac provides a detailed, step-by-step user manual; here, I present a summary of how it worked for me in actual use.

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