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The New Digital Audio Revolution

When the compact disc was introduced by Sony and Philips in the U.S. in 1982, people went nuts. Never had the average listener experienced such sonic reproduction in terms of what were then acceptable audio specifications. That’s because prior to digital music, analog sources were judged on certain endemic distortion specifications such as total harmonic distortion (THD), and wow and flutter.

The CD changed all of that because unlike analog, its defects were not necessarily symmetrical-so the distortion was not harmonic at all. And since there was also no real time-based distortion, wow and flutter was no longer a factor. Instead, the CD has introduced an entirely different set of issues based around artifacts present within the conversion process from digital to analog that produce a harsh, ringing sound. And CDs possess a lack of information in the low-level musical passages, which can obscure musical subtleties and overtones.

The Red Book standard CD format is based on a pulse code modulation (PCM) format that delivers a total of 65,536 possible values. And as anyone in computers nowadays would know, that is not a lot of data; hence the sound, while acceptable to most, left many audiophiles and serious music listeners disappointed.

Over the past two decades, some of the more creative audio engineers have improved upon the CD’s original PCM format by creating more accurate digital-to-analog converters (DAC) and many-times oversampling. By using 18-bit and 20-bit DACs to process high-resolution oversamples and original 16-bit information, the improved headroom allowed for better resolution during softer passages. Some of the more exotic CD hardware manufacturers have installed on-board computers to interpolate the PCM data and thereby create a higher resolution all around. This is very costly-for example, high-end audio manufacturer Linn Sondek has produced perhaps the most critically acclaimed Red Book CD player of all time: the CD12. Its cost? $20,000!

Other true audiophiles have opted for two-piece CD systems that consist of a separate CD transport and digital processor. Audiophile CD transports can range from about $2,500 for the Theta Jade transport to $8,000 or more for the Wadia 270. Then you have to add a digital-to-analog converter unit like the Muse Model 296 that sells for about $3,000. By spending these copious sums, you can begin to hear true lifelike realism and soundstage from a format not really conducive to audiophile performance.

But these are all Band-Aids for a fundamental issue: the fact that there is not enough recorded information to deliver the ultra-high resolution that audiophiles crave. The human ear is purported to hear from 20 Hz to 20 kHz (although most adults can only hear to about 15 kHz or so). The CD only samples at 44.1 kHz. (The Haas Effect dictates that the sampling rate has to be double the highest frequency so 44.1 kHz yields a high frequency limit of 22.05 kHz.) However, musical overtones often resonate much higher than 20 kHz. And although they cannot be heard in and of themselves, they contribute to the overall gestalt of the opus. The general complaint is the standard Red Book CD sounds cold and sterile, and is missing the verve of a live performance, which is caused by the lapse of these overtones.

Super Audio CD-The First True Audiophile CD Format

At the highest end of the digital spectrum is Sony’s Super Audio CD (SACD). This brand new format is designed specifically for audiophiles who need to hear more of the music than ever before. An SACD player can accommodate four types of CD formats. The first type is a disc that sports a single high-density layer that will store high-resolution music. This HD disc is not compatible with a standard CD player. The next is a dual-layer disc that can hold twice the playing time. The third is also a hybrid format that holds an HD layer to be played on an SACD player, as well as an embedded standard layer so the same disc can also play on a standard player. And finally, an SACD player will play all standard CDs as well.

Instead of the PCM digital encoding format, SACD uses a direct stream digital-encoding format. This revolutionary new system eliminates most of the input filters that have heretofore caused all of the unwanted digital muddiness and noise mentioned above. Instead it uses a single analog filter in the output stage. As opposed to the 44.1 kHz samples delivered by the standard CD, the SACD can deliver up to 2,822,400 samples per second! This kind of data flow will recreate even the subtlest ambience and reverberations left off by previous CD players.

Currently there are more than 50 SACD titles available-mostly from Sony Music as well as many audiophile labels. The audiophile critics have gone wild with praise for the sonic excellence that SACD delivers. And right now, Sony has priced SACD for the extreme audiophile. Their flagship player, the SCD-1, sells for $5,000 and the “economy” version, the SCD-777ES, sells for a mere $3,500. But they are both selling briskly to people who have a predilection for high-end stereos.

The question becomes whether SACD will survive the onslaught of DVD audio players slated to hit stores sometime this summer. DVD audio-being spearheaded by the folks at Panasonic-uses the high-density DVD system for storage. It will be based mostly around a six-channel surround sound system for audio rather than Sony’s standard two-channel stereo system used for SACD. Soon, many DVD video players will also play DVD audio discs, that promise to have improved fidelity over the standard CD, as well as delivering music in six-channel surround sound. DVD audio was supposed to be available last year, but the secure copy protection code was hacked into and posted on the Internet, and all of the players had to be recalled at the last minute. As of now, manufacturers have offered no official street date.

DVD audio is sure to be popular given the popularity of DVD video-considered to be the fastest-selling consumer electronics product of all time. It will also be considerably cheaper than SACD-under $1,000. The question becomes, Can the two formats coexist?

Time for Data Reduction

It’s true that improvements in digital processing speed allow for dramatically increased media storage capacity. (The conventional wisdom is that data storage doubles every 6-9 months.) And that increased capacity allows for more data flow and a higher sonic resolution. But with increased data comes the issue of increased data processing time. A traditional CD can store only 640 megabytes, which translates into 74 minutes and 22 seconds worth of music. But that’s way too much data to download off of the Internet quickly. And if you’ve been reading any newspaper or magazine lately, you’ll know that this is most likely the future of music sales and distribution.

Data reduction or compression algorithms allow for more minutes of music represented by less data, and hence delivering lower fidelity. Sony really pioneered it with the MiniDisc, which was introduced about a decade ago. MiniDisc is a small, 3.5-inch disc (as opposed to the CD’s 5.25-inch size) that holds the same number of musical minutes as a CD (74:22), but uses a data reduction algorithm called ATRAC to reduce the data so that it fits onto the smaller format disc. ATRAC looks for similar notes played simultaneously where one is much louder then the other. Assuming the human ear cannot discern the difference between two similar notes if one is much louder than the other, ATRAC data reduction will eliminate the softer note. Most people cannot tell the difference between music whose data has been reduced by ATRAC and a full-blown CD sound, especially when using a portable Walkman-type stereo outdoors with a lot of background noise. But real audiophiles and music lovers can discern between the two because data compression or reduction systems remove much of the music’s timbre, overtones and subtleties that make music special.

Sony’s newest MiniDisc player is the MZ-R70, which Sony is touting as the perfect digital archival medium because it is durable, inexpensive (blank MDs cost about $7 vs. the $14 cost of blank CDs meant for music recording). And with MD, you can re-record up to one million times on each disc.

Motionless Digital Archival Storage

So-called flash memory-similar to the RAM memory in your computer-is the next wave of digital music delivery systems. MP3 is the term that most people are familiar with for this genre. And it is technology used by many of the music Web sites. But it has also become a generic term, which is used for all music downloaded from the web. In fact, there are many different encode/decode systems that compress music for faster transfer over the web. These CODECs have been produced by various software manufacturers and include Microsoft’s Window Media (WMA), Real Audio’s R2, Liquid Audio’s LA, as well as Panasonic’s upcoming AAC CODEC. Each uses a different system, but all accomplish the same thing-they reduce data up to 10 times or more so that songs can be downloaded quickly (especially via 28.8 or 56k dial-up modems).

The quality of the sound downloaded from the Web depends upon the amount of data allocated to each song. If you try to cram two hours worth of music onto a 64k flash memory card, it will sound worse than if you put one hour onto it. This is along the same lines as SP mode and EP mode on your VCR: SP mode delivers a better picture, but you can only squeeze two hours onto a single tape, as opposed to six in EP mode.

At bit rates of 132 KBPS, you can have pretty decent fidelity with about an hour’s worth of music. You can get two hours at 66 KBPS but it won’t sound as good. But even at 132 KBPS current CODEC algorithms do not sound as good as the MD ATRAC system, and that doesn’t sound as good as the standard compact disc. Perhaps one day, when they really have data compression down to an art, you won’t be able to tell the difference.

Many people opt to store their downloaded digital music on their PC. Others want to take it with them using an MP3 portable player. These players use a stationary flash memory card-similar to your computer’s RAM-which can accommodate up to two hours worth of music depending upon the fidelity. The Diamond Audio Rio player was the first MP3 player on the market. Since then, a slew of manufacturers has gotten into the game.

One up-and-coming MP3 vendor is the Memory Corporation Group, which produces the Music Store and Soul Mate MP3 Players. The Soul Mate is a compact MP3 portable player that is extremely inexpensive-around $130. It contains 48 MB of memory so it can store an hour’s worth of music. It takes about 20 seconds to download 60 minutes worth of music. It comes with download software, headphones, a rechargeable battery, docking station and an AC adapter.

The other very interesting product from Memory Corporation is the Music Store. It has a high-capacity hard drive built-in that is capable of storing the data from 200 CDs in memory! It will also store more than 200 hours of downloaded music. It interfaces with your stereo system so you can listen to any of the discs or songs in any order-with no moving parts. It also has a docking port for the Soul Mate portable player. The Music Store will download an hour’s worth of any combination of songs onto the Soul Mate in 20 seconds. The Music Store costs around $500, including the Soul Mate, and $400 without it.

Enter SDMI

Until now, music that is downloadable from the Web has been free, a phenomenon enjoyed mostly by teenagers. They can grab a free song off of a Web site and either keep it on their computer, burn it onto CD or transfer it onto an MP3 player. Generally, these songs are by up-and-coming artists who have not yet been signed to a major record label. This is great for the short term, but eventually musicians want to get paid-even unsigned ones! Things will start to move away from free downloads with the use of an encryption process called SDMI or Secure Digital Music Interface. This system allows for the personal consumption of music but prevents people from making unlimited digital copies. Each time a user downloads a song, and pays with his or her credit card, it is tantamount to a licensing agreement for the song. Depending upon the terms of the individual agreement, you can “check out” the song off of your hard drive a set number of times (usually three times). That means that you can make three digital copies, and that’s it. If you want more, you’ll have to pay again.

Sony is the first to introduce a portable digital music player that utilizes the SDMI standard. It uses the Sony-developed flash storage medium called Memory Stick. The newest model, the NW-MS7 Memory Stick Walkman utilizes a removable version called MagicGate™. This data store device can hold 64 MB of data; a standard CD holds 640. But using Sony’s new ATRAC-3 10:1 data reduction system, this Walkman can hold up to 120 minutes of data, depending upon the bit rate used.

The NW-MS7 is about the size of a stick of butter. And you can change out the Memory Stick cards, so you won’t have to re-record over the same songs every time you want to download something. As with any first-time technology, the Memory Stick Walkman isn’t cheap. This model sells for about $400-but additional Memory Sticks are more than $150 each!

An alternative to the removable MagicGate™ media is to go with the cheaper embedded flash memory Walkman, the NW-E3. This is smaller than the MS7-about the size of a cigarette lighter. The only issue is that once you’ve used up the 64 MBs, you have to record over the songs.

Another very cool thing about downloading music from the Web is that you can also go and get your titles and artist information for most albums. Once you download your music, you can go to www.cddb.com and also download the song titles and artist credits, etc.

Originally Published