Music in the Round #70
I have long maintained that we audiophiles, and the manufacturers that serve us, end up optimizing whatever is thought will best sell in the mass market. What can we hope to get out of new technologies like Dolby Atmos that might be applied to listening to music not recorded with it, particularly multichannel recordings? Fundamental to this is object-oriented processing, in which individual sources (a voice or a sound) are distributed among the channels of a surround system to appear at their proper positions in space, whether or not a loudspeaker occupies that spot. What I see as being of stealth value for music reproduction is that object-oriented processing might bring with it the development of advanced room-correction systems. Note: None of what follows is based on inside information, but on my speculations of what can be developed from the new codecs and hardware.
All the well-known consumer room-correction systems focus on the optimization of a horizontal array of speakers. Some, like Audyssey, even insist that all the measurement microphone positions be at the height of the primary listener's ears. Trinnov Audio, which uses a unique microphone array that can discern speaker positions in all three planes of space, can also "acoustically" correct each speaker's position in 2D or 3D space by sending signals to the other speakers in the room. In its present incarnations, it creates phantom sources for each speaker so that all speakers are at standard ITU angles with respect to the listening position, and all are in the same horizontal plane as the listeners' ears. In other words, it treats the signals of the five or seven or more channels as acoustical "objects," each of which needs to appear to emanate from a particular direction, and processes them so that what emerges from each speaker is not merely a single channel's signal but a signal that, in concert with what comes from the other speakers, helps create a virtually correct array. When I reviewed the Trinnov Optimizer, it occurred to me that the addition of more speakers, even with only 5.1 or 7.1 channels, could result in even greater and more complete optimization of proper signal source placement and correction of room modes.
At the 2014 Consumer Electronics Show, Dirac demonstrated a prototype of their Unison room-correction system. This uses all of the speakers in a standard horizontal speaker array as active correction devices for room modes. This reminded me of such active but singular room-correction devices as the Bag End E-Trap and the Phantom Acoustics Shadow active low-frequency acoustic controlthough those devices, as discussed by Keith Howard in his article Anti-Node: Active Room-Acoustics Correction," include microphones and electronics to detect and absorb modal energy. Dirac has yet to divulge the Unison's exact operations, except that "it is based on ideas from the fields of active noise control, sound field synthesis and room correction where our company has conducted research for many years." However, one can infer that the use of more and better distributed active devices should result in better correction, and indeed, the Unison demos were impressive for their elimination of room modes with minimal effect on the tonality of the system.
To me, it is a small conceptual jump from these observations to infer that a system with 3D speaker arrays, such as with Dolby Atmos (or Auro Technologies' Auro-3D) could do double duty as a complete platform for room correction. As of today, all the basic parts are available in the DataSat RS-20i and Trinnov Altitude32 processors. Although I was hugely impressed with my son-in-law's 5.1-channel system, which included an RS-20i and Dirac Live, it boggles my mind to think what the addition of height speakers could do for multichannel music, even if only to more completely optimize room correction.
NAD Masters Series M17 A/V surround-sound preamplifier-processor
Despite a tradition of marketing stereo and multichannel components of conservative appearance and solid engineering, NAD has been more adventurous than most audio manufacturers in pursuing digital innovation (footnote 1). In my review of the T 187 preamplifier-processor in January 2013, I traced "their original digital preamp, the 118, which I reviewed in the July 1998 issue; to the M2 Direct Digital amp, reviewed by [John Atkinson] in March 2010; to the Masters M51 high-resolution DAC, reviewed [in July 2012] by Jon Iverson; and their Masters M50 and M52 music-streaming devices." I concluded that "NAD has never simply repackaged available chips and modules, but has always gone their own way."
Somewhat in counterbalance to this, NAD's Masters Series has coupled strikingly sophisticated appearance and construction with solid but conservative engineering; eg, the M15 HD2 pre-pro and M25 seven-channel power amp. However, in an informative demonstration of NAD, PSB, and Bluesound products for Stereophile staff last June, I saw that things had changed. First was the impressively smooth integration of Bluesound technology into NAD's Masters M12 Direct Digital preamplifier-DAC, and the promise of same for the Masters M17 multichannel pre-pro. Second was the use of Hypex nCore technology in the two-channel Masters M22 two-channel and M27 seven-channel power amps. Third was the new industrial design by David Farrageso fresh that I just wanted to get my hands on them. So I did.
The Masters M17 ($5499) is much slimmer, cleaner, and sleeker than the Masters M15 or, indeed, almost anything else out there. It arrived in a carton weighing more than half as much as the 24-lb M17 itselfunless someone took an axe to the box, I can't imagine how an M17 could be damaged in shipment. I removed the M17 from a thick brick of firm plastic foam, and opened the slip-knotted fabric bag as if it contained a precious jewel. The M17 looked even better than I had recalled from seeing it at NAD's demo.
The M17 measures 17" (435mm) wide by 6.1" (156mm) high by 15.1" (386mm) deep. Its black front panel stands proud of the contrasting matte-silver frame, and the color of its illuminated NAD logo indicates the power status (Off/Standby/On). There are also a large, touch-sensitive display and a black volume knob. Centered on the top edge of the frame is a touch-sensitive Standby/On switch. That's it.
Across the top of the rear panel, beginning at the left, is a 7.1-channel array of XLR audio outputs. To the right of these is a matching array of RCA outputs, with the addition of an output for a second subwoofer. Below these are four Modular DC (MDC) modules that permit the user to change and update the hardware without having to return the M17 to the factory or replace it entirely. The review sample had these four modules:
1) Digital Video: 6 HDMI inputs, 2 HDMI outputs, RJ45 Ethernet port
2) Analog Video: composite in/outs (3/1), component in/outs (2/1), Zone 2 composite output
3) Digital Audio: 4 coaxial inputs, 4 optical inputs, 2 coaxial outputs, 2 optical outputs
4) Analog Audio: 7 inputs, 3 Zone outputs
At bottom right on the rear panel are an IEC AC inlet, an unswitched AC output, and the master Power rocker. Above these are IR and 12V trigger ports, trigger control, and an RS-232 port.
I immediately saw that the M17 has no USB port, and that its Ethernet and RS-232 ports can be used only for device control rather than audio data. After NAD's impressive demo of the M12's streaming abilities, this shocked me. However, NAD assured me that a module supporting streaming and Bluesound would be available by the end of 2014. Bummer.