Find yourself waiting for an HDCD release? Most people don't switch to a new audio format until a recording is released that they are curious about. At the top of my list would be Gavin Bryars "Jesus' Blood Never Failed Me yet." Actually any Bryars release on HDCD (or the new DVD Audio format) would cause my ears to twitch. 24/96 digital sound is a dramatic advance. Any home recording enthusiast can test the difference that a wider bandwidth alone can make.

      In some respects, this is what audiophilia is all about: How much closer can we get to the original recording? My own experience with evaluating a new format dates back to the North American launch of the CD in 1983.

      I was an employee of PolyGram at the time, and like most other employees, I was excited by the prospect of artifact-free sound. I found noisy records to be annoying. Warped and off-center records were worse still. Most warps are audible, and off-centering caused pitch instability that only added to the musical experience when the recording itself was bizarre. The Small Faces 'Itchygoo Park' might not sound too bad off-center, whereas a classical recording of Ivo Pogorelich playing Ravel's 'Gaspard de la Nuit' would be bothersome on bad vinyl. The sustained piano notes would sound unnatural as the stylus attempted to track the poorly manufactured record.

      The CD was supposed to do away with these headaches. Notwithstanding the technical limitations of the format itself (not enough bandwidth: Nyquist was wrong about two times oversampling being sufficient to capture the nuances of music. Sonar uses eight times oversampling to construct an accurate positional impression, for instance), a well manufactured CD does a fairly good job of satisfying our need to hear good sound.

      My first venture into CD was underwritten by PolyGram. All employees were able to purchase CD's at the company price (under $12.00 CDN in 1984), and they just about gave away the CD players, which were top of the line 16 bit PHILIPS CD303's that had advanced error correction algorithms designed to make even the most difficult discs tractable. I got a demonstration of just how superior the error correction of the PHILIPS machines were when one of my discs, Sibelius' 2nd Symphony mistracked during playback. The CD303 managed to play through the fault (a physical one on the disc surface) where no other contemporary machine could. PolyGram's QC department had each and every existing machine in manufacture for comparative purposes and in the early days of the format, they routinely tested CD players for playback stability, mistracking and so on. In the early days of the format, manufacturing reject rates were very high for discs, sometimes exceeding 50%. There was only one source of discs at the time: PolyGram's PDO division manufactured them in Hannover. As the global source of a format that had yet to recieve widespread acceptance, PolyGram wanted to ensure that their carefully QC'd discs would play back acceptably on the machines manufactured by other audio companies. The first years were touch-and go: only Sony came close to the playback standard set by PHILIPS.

      At the time, I thought that the two primary criteria for purchasing a CD player would be features and error correction.

      Error correction? Who talks about that? Years into the format, there is no guarantee that a new CD player will successfully track some of the CD's that one of my ex-girlfriends came to hate. One time, in a fit of pique, she took a knife to the surface of Eugenius' 'Mary Queen of Scots' and Mike Oldfield's 'Amarok.' My current PHILIPS transport can navigate both, hardly any other machine can. 'Amarok' causes most players to mistrack around the 17 minute mark. It is just like a scratchy record: The player will keep on trying to play the same passage. It can sound quite ambient at times. The secret to playback success in even the oldest PHILIPS 14 bit machine lay in skipping forward over the damaged or unplayable portion. Many machines won't even allow you to manually bypass the damage, and that is just plain bad design. My home Sony player fails this test.

      Are the new DVD machines any better? Will HDCD machines do a better job than everything else? A recent survey of DVD machines suggests that they are no better or worse than the average CD player, and I'm not certain that I have anything to say about HDCD performance, because I'm still waiting for something to be released on that format that is worth listening to.

      Manufacturers don't seem to give the subject of error correction the time of day. Many high end ancillary accessories are designed to improve the quality of the digital bitstream. Separate DA converters and Jitter reducing devices imply just that. But neither can do much to improve physical disc errors, although arguably, both are designed reconstruct the downstream signal in a manner that should circumvent tracking errors that are caused by the laser pickup. Jitter reduction devices do so by largely ignoring the clock signal generated by the player in favor of an externally constituted clock.

      But back to Gavin Bryars for the moment: Why have I chosen this recording over dozens of others that could be used for evaluation? For one thing, the noise floor is deep, and there is a large amount of low level detail that I can only guess would be clearer at a higher sampling rate. For those of you who do have the ability to record on your computer, the differences between 96 kHz and 44.1 kHz are dramatic, even at a 16 bit word depth. Surprisingly, reduced bandwidth recordings (try 33 kHz), don't sound much worse than the CD standard at 16 bits. When you start to get lower, the shortcomings become apparent very quickly.

      New sound cards are coming on to the market that, when combined with professional recording software, will allow recording at 24/96. My own system cannot handle a 24 bit word depth, and I question how useful all of those extra bits will be. Existing CD's are close to 14 bits, with two left over for redundancy checks, and if I do the math right, there would seem to be a point of rapidly diminishing returns beyond 18 or 19 bits at 96 kHz.

      I'm not about to complain about having more bit-depth than is required. Nor am I about to complain about having an astonishingly deep signal-to-noise ratio. But I question how much better the existing catalogue of recorded works will sound in the new formats. We are not being offered 8 times oversampling with the new standard, for starters, and in moments of dark thought I worry that should the new format become a de facto standard, many record companies will merely upsample their existing catalogue, rather than go back to the source recordings.

      Fortunately, there is a trend toward recording at the highest possible resolution in-studio. These recordings are then down-sampled to 44.1 kHz at 16 bits with a variety of anti-aliasing strategies applied to retain the integrity of the original recording. With the introduction of multi-layer DVD's that feature a conventional CD type layer on top (for backward compatibility) and high-resolution DVD multichannel sound on the inner layers, it should be possible to compare the formats on one disk, with the CD and DVD players of your choice.

      You can rest assured that the audio reviewers at the AIG will be doing just that.

Charles McRobert