December 2001

The Software

Finally! It certainly took long enough, but nowadays you can actually go down to your local mall and find a selection of DTS CD, DVD-Audio, and multichannel SACD discs. Each disc type has its own advantages and disadvantages, and each certainly has its own proponents and detractors -- and the music ranges from classical to pop to avant garde -- but the important thing is that, at last, the discs are available.

What these discs have in common is that they build upon the two-channel standard that has been with us since the advent of stereo. Although there have been other attempts to create multichannel musical reproduction before, they lacked the high resolution available with today's digital information-storage formats. The sophistication of the multichannel music that exists right now far exceeds anything we've had to work with in the past. And while it does have a long way to go, the selection as well as its implementation are improving all the time.

But before we get ahead of ourselves, let's take a look at each type of music-delivery software currently available.

DTS CDs

DTS entered the multichannel-music sweepstakes early on by producing DTS-encoded 5.1-channel CDs. DTS is a major player in the production of movie soundtracks for use in commercial theaters and, more recently, the home-theater environment. Although they compete with Dolby Labs, their software and decoders often coexist in the same products and use the same hardware. For instance, an increasing number of DVD-V movies have both Dolby Digital and DTS audio tracks. The vast majority of home-theater processors possess both decoders. It is therefore quite easy to toggle between the two while watching a movie or concert DVD. DTS decided that, with home theater virtually driving the consumer-electronics market, an opportunity existed to expand into music using the same technology, since appropriate playback systems were in place to utilize it.

For the first time, consumers were able to experience surround music over existing DTS-compatible systems, using the CD player as the delivery system. DTS CDs can produce excellent sound quality, although admittedly, its use of the CD limits its available storage capacity.

The requirements for DTS CD playback include a 5.1 speaker array with appropriate amplification, a CD player capable of outputting a DTS-encoded digital signal, and a processor capable of decoding DTS. This describes many, if not most, home theaters. One of the first major bands to embrace DTS with their own material was the Police, with a remix of "Every Breath You Take." Currently there are approximately 120 DTS-encoded CDs available in several genres. Some pundits see DTS CD as a segue to DVD-A, which is supported by DTS.

DVD-A

DVD-Audio was designed specifically as a high-resolution format to deliver multichannel audio. The available space on a DVD-A disc, like that on a DVD-V disc, is approximately seven times that of a CD. This enables it to store higher-resolution data in multiple channels. The DVD-A disc uses the same Pulse Code Modulation (PCM) recording technology the CD does, but DVD's available storage space allows much higher sampling rates and word lengths. Several industry leaders including Panasonic and Pioneer support DVD-A as the eventual replacement for CD.

The higher fidelity promised by DVD-A is partially related to the way data is compressed for storage. A form of lossless (as opposed to lossy) compression was developed by Bob Stuart of Meridian Audio; Meridian Lossless Packing (MLP) enables increased data storage without discarding any audio information. Thanks to MLP, DVD-A can deliver up to six channels of 96kHz/24-bit information.

DVD-A utilizes the industry-standard 5.1 configuration and can therefore be played back over existing speaker/amplifier packages designed for home theater. A DVD-A disc will not play in older DVD-V players, however, unless a DVD-V track is included on the disc. Many of the newer DVD players include both DVD-V and DVD-A capability, though you should make sure this is the case before you buy. If you’re used to DVD-V, DVD-A will be similar in playback setup -- with one significant exception. Due to concerns over copy protection, there is currently no digital-output capability on the players. This has been a major stumbling block for end users, primarily because this makes it impossible to utilize the bass-management and programmable-delay functions available in A/V preamp-processors and receivers.

Currently there are add-on consumer products available that "fix" some of this lost functionality, but only in the analog domain. However, new players are beginning to include these functions. Without a digital output, this is a necessity. For playback, six analog channels are output from the DVD-A player to six analog inputs on a component with volume control and either separate or built-in amplifiers. The receiver/processor in this instance is simply a six-channel level control, since its processing functions are essentially bypassed.

An industry standard for a DVD-A digital output is rumored to be in the works, but don't expect it before the first of the year. Purportedly, it will be a FireWire (IEEE) connection, although I personally will believe it when I see it.

That alone would greatly enhance its functionality in the hands of consumers, and help to grow the format. The general trend recently has been for manufacturers to include DVD-A capability on new DVD players. With DVD-player sales topping the 20-million mark in 2001, this is seen as a major boon in actually landing players in the homes of potential music lovers. The theory is that this growing base of players will provide a marketplace for multichannel recordings (by riding the coattails of DVD-V).

SACD

The Super Audio Compact Disc player was released as a delivery system for Direct Stream Digital (DSD) recording technology. Developed by Sony and supported by Philips, SACD can come in several forms. The first generation of music to be released was single-layer two-channel recordings, which required an SACD player for playback. Soon after, a number of hybrid (or dual-layer) discs began shipping, which are backwards compatible with existing CD players. More germane to our discussion was the subsequent release of the first multichannel SACD players and software.

Although SACD and DVD-A use vastly different recording systems, they have several things in common. First, like DVD-A, there is no digital output available for use with typical consumer products. I use the term "typical" because right now there are companies that utilize proprietary digital links, but only for use between their products. Therefore, we have the same scenario as DVD-A: six-channel analog outputs feed the six-channel analog input of the volume control/amplification stage. Also like DVD-A, there is little provision at this time for externally controlled bass-management and delay-time programmability. The bright news is Sony’s Multichannel Management, which does offer some much needed functions, such as the adjustment of speaker size and delay times. This should be seen as the first real attempt at making multichannel players useful to the masses.

Due to the incompatibility of current processor-based digital-to-analog converters, the future is sketchy with respect to how it will interface with most consumer systems, at least outside of the six-channel analog connection. The audio quality can be striking, though, and with a six-channel preamp, this could be overcome, though not in a typical home-theater-like configuration where the processor is utilized for these functions.

What’s the point?

Setting aside DTS CDs, we have two delivery systems that offer so much more capability than we had before. The opportunity to have high-resolution multichannel music in either SACD or DVD-A bodes well for a vastly more realistic musical experience in the home.

Caveats? Sure! If you do not already own a home-theater rig, setting up a system with multiple speakers can be a daunting proposition. I’m not going to tell you the future is clear and that you should rush out to buy multiple full-range speakers and a load of amplifiers. A little waiting may help clear the picture a bit, which could make some equipment more or less useful. One thing you can count on, though, is that whether or not such things as subwoofers and height-information channels become widespread, rear speakers will be used, so adding surrounds would be a good, safe move right now.

We’re going to keep track of the almost daily shuffling to see what shakes out. When we know, we’ll give it to you here. You can count on that.

...Jeff Fritz
jeff@soundstage.com

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