The advent of the Meridian 808.2 CD player and Rober Harley's comments on it prompted me to write this piece on standard resolution ("Red Book") digital audio. To be sure, advancements in playback have been very real over the past two decades. But with the advent of minimum-phase / "apodising" filters and the massive improvement they brought to CD, a lot of people will be wondering if 16 bits / 44.1kHz sampling was enough on disc, for playback.
The answer, after decades of debate and endless argument amongst audiophiles and audio writers, seems to be yes, to this big question. Beyond mike technique, venue, etc. an encoding format has three main areas of concern: capturing (sample rate, etc.) production and playback. Many audiophiles think there are only *two* main areas concerning a format - recording and playback. This is wrong - there's one more in the middle !
As it turns out, the areas affecting CD's sound were the last two - production and playback. The production problem was solved years ago and was an instant fix, as I show below. But first an overview: 16-bit digital encodes 95db of dynamic range - roughly 25db more than a large symphony orchestra produces. And orchestras produce far more "range" than a rock band or string quartet, both of which have dynamic ranges in the 50's db. This fact links up with important findings in recent years by audio researchers. One of them is Bob Katz. - Bob says for "original sources", 16 bits IS ENOUGH for all kinds of music. By "original source", he means the encoded music before it was processed. This observation was derived from controlled listening experiments done over the years, that either Katz or others conducted. The problem, as (all) recording engineers know, were the intermediate calculations done on the signal after recording - the "DSP processing" done in production. With DSP, there were losses in a 16 bit recording...losses that eroded into the music - esp. symphonic-style and grand piano.
But in the early 1990's a technique came along that cured the problem - 20 BIT RECORDING. This would absorb all the production losses that hurt 16 bit recordings. Right after this, a technique called noise-shaping came out - another improvement - but this time for playback (on disc). As for the CD-standard, I quote Malcolm Hawksford from the March 1996 Stereophile article "Bits is Bits ?": "When correctly dithered using triangular PDF dither, a 16-bit digital audio signal possesses a dynamic range of 93.3db with zero distortion and zero noise modulation. The 16-bit format holds the possibility of even *higher* subjective dynamic range - up to 18db more - with minimally audible noise-shaping employed during CD mastering".
Knowing this, why would *anyone* desire a new audio format ?!! Zero distortion, zero noise and dynamic range of 110db - that's "not enough" ?? One of the arguments for more bits was that "it's not the number of bits available...but the number used at one time". Yes, but that was a *production* issue - not a capturing or playback-disc issue !! The same goes for the sample rate - *if* more than 44.1kHz was needed, we got it - in capture - starting 16 years ago. The problem was that audio writers never explained the (real) virtue of 20-bit recording and that 16 bits might be enough, on disc
All this wasn't enough, however, as advances in playback were needed as well. But the issues in playback seem to concern the laws of electrical current and audio-chasis design much more than the "band-aids" needed to improve CD sound. Yes, CD was "upsampled", etc...but let's not forget that some CD playback systems *didn't* upsample and produced great sound - like Zanden. In other words, most of the parameters concerning digital playback had to be improved anyway - no matter how many bits were on disc.
That said, it's not a surprise that CD sounds as good as it does today. Some audio writers are struggling to hear a difference between the Meridian player mentioned above and true Hi-Rez audio. Robert Harley, strangely, did not compare the 808.2 CD player with his Hi-Rez files. That's probably because CD sounds a lot closer to Hi-Rez than he thought it could (or should). But it's right in the specs.......
These (new) observations are not a surprise to everyone. Below are four articles I dug up, starting with J. Gordon Holt from the mid-1980's and continuing forward. A little perspective and some solid answers is what we need. Enjoy......
Finally, an explanation as to why DVD-A sounded better than CD. I mean, if CD's specs contain all we need for sound, then why was DVD-A (which itself needs to be filtered, noise-controlled, etc.) preferred ? (at least through Meridian players).
Towards bottom - "micrograph" pictures