man@bocar.UUCP (M Nevar) (06/07/85)
The Absolute Sound Of What ? One of the things that distinguishes a dedicated audiophile from John Q. Public is that he has some notion of what audio fidelity is all about. Because he understands what the word "reproduction" means, the audiophile thinks in terms of a relationship to an original sound. This original is, of course, the sound of live music, and the touchstone for ist reproduction is accuracy. Unfortunately, though, we *don't* really compare the reproduction with the real thing -- because we can't. Only a recording engineer can saunter back and forth between the real thing (which takes place in a studio or hall) and the reproduction of it (in the control room with its monitor system). We audiophiles must be content to compare the reproduction with what we *remember* to be the sound of live music. Even the amateur recordist must carry the memory of the original sound home with his tapes in order to evaluate them. And that memory may not serve us all that well. Few of us have learned to be able to break live sound down into its components, and to observe what each sounds like. Most of us remember only an overall impression -- the gestalt of the thing. And many of us must admit, to ourselves at least, that we have not heard live music for years or, worse yet, never at all. For the vast amount of audiophiles then, the reference standard is not the absolute sound of live music, but an imagined ideal--a mental picture of how we remember it having sounded or how we would *like* it to sound. At this point, accuracy becomes a dubious criterion because of the vagueness of the original to which we compare the copy. System evaluation becomes a (simple?) matter of "it's good if it sounds good." The problem with this is that one man's good is another man's distortion. Different people listen to and assign different orders of importance to different aspects of reproduced sound. Thus, while two very picky listeners may agree that a system has good bass, good highs, and a colored middle range, they will disagree as to how *good* the system is if one happens to be critical of the highs and lows while the other is critical of the middle range. In short, we really don't have any way of reliably assessing the accuracy of reproduced sound. Even a recording engineer cannot be confident of the sound of his own recording, because what he hears in the control room depends on his monitoring equipment, which is no more -- and often less -- accurate than a home system. (many pros do not in fact aim for realism at all but for what thet call "commercial sound" -- one that will sell. Thus a recording may not even have the *potential* for sounding realistic.) There are two approaches to select from when looking for the holy grail of systems. The first is for the casual audiophile who chooses a record label whose releases he favors and will tailor his system to sound best with most of the label's releases. This is not *true* accuracy. Perfecionist audiophiles, on the other hand, usually aim for maximum accuracy in the playback system itself. If the system accurately reproduces what is on the recording, the best recordings will produce the most natural sound. This seems like an elegantly simple solution, but there's a flaw. In order to ascertain the accuracy of a disc's reproduction, we mus have an original to compare it to. Butwe can't compare it to the sound that was fed into the master-tape recorder, because that sound was lost forever when the recording session ended. The closest we can get to that original signal is the one that comes from the recorder when the tape is played back. That, after all, is the signal used to cut the disc, and if the disc sounds the same as the tape, then we know our record-playing system is accurate. Right ? Not necessarily -- the record cuttin and pressing system was optimized based on a comparison to the original sound, but with probably a totally different phono system than the one you use at your home. Before approving a new release, a record producer is sent a test pressing of it. (Some record producers base their disc-cut approval on the sound of an "acetate" (a direct cut on the same kind of lacquer-coated aluminum disc used for making the production master). This is a mistake, because the lacquer on the acetate is much more yielding to a passing stylus than is vinyl, making the high end sound very soft. The extremely "hot" high end on many commercial releases is a direct result of the producer demanding (and getting) enough HF boost from the cutting engineer to compensate for the dullness heard on the acetate cut.) He plays this test pressing through his reference system and compares it to what he hears directly from the master tape. If they don't sounf alike, he tells the cutting engineer to make appropriate equilization corrections for the final release cut, or to simply re-cut the disc with the same equilization. Wouldn't this ensure that his disc sounds like the original tape? Not quite, because it is more likely that his phone system and preamp have significantcolorations, which will make the disc sound different from the way it "actually" sounds. Why, then, should our perfectionist record producer trust his playback system? Because He carefully chose it to make his records sound as much as possible like his tapes!! We've all heard of Catch 22, but in case you're unsure of its meaning, it is about circularity -- in reasoning. A popular case is the chicken or the egg question. Then there's the apocrytical "Timbuktu parodox" which relates the story of the retired sea captain who fires a cannon every day at the precise moment the town hall clock says 12 noon, while the town hall custodian checks his clock every day by the sound of the 12 O'clock cannon. What in fact *does* a record sound like? Think for a moment before answering. It has no sound at all. Hold one up to your ear, and what do you hear? Nothing of course. To hear what's on a recording, you have to reproduce it through a phone system. And what does that phono system *really* sound like ? It sounds like the record with various things added or subtracted. And the music goes 'round and 'round... There really *isn't* any way of knowing precisely what is the sound of a record or its player. This is one reason why, in this age of high technology, audio continues to be such a cabalistic field. Where knowledge fails, mysticism moves in. But just because we cannot make *absolute* assessments of disc-reproduction doesn't mean we should abandon the accuracy criterion altogether. There is, in fact a way we can get reasonably close to the ultimate truth about an analog disc and its player, and that way -- believe it or not -- is through the Compact Disc. The CD has all along been touted as an absolutely accurate recording-playback medium, no doubt to the embarrassment of those manufacturers who so promoted it. Even the mass circulation hi-fi magazines have been reporting that some players sound better than others, and that the best are getting better as time goes on. But another question which has assumed growing importance is just how good the Compact Disc system actually is, because the answer will determine how far the CD can go towards meeting the needs of the audiophile who cares about accuracy. Many audiophile record-manufacturers claim that CD sound is "virtually indistinguishable from" the sound of the original master tapes. Even allowing for a certain amount of hype, this indicated that CD offers us the most direct path back to the sound of the original master recording. But how much *does* a CD sound like its master? To my knowledge, the only investigation of this was done a couple of years ago by England's Hi-Fi News & Record Review. Those listening tests involved direct comparisons between the sound of some Decca CDs and their digital master tapes. The test results were not thought to be entirely conclusive. They agreed that the CDs sounded pretty much like the tapes, but some disagreement over how important the minor differences were. HFN&RR's experiment is already outdated anyway. Since that time, the audio quality of the best CD players has improved dramatically, while many professional recorders have remained the same. And the conclusions of HHN&RR's tests were not quite the same as an analog disc/tape comparison, because a set of spurious electronics were introduced into the "original" signal: the digital recorder's playback circuitry. When mastering from analog, the original signal -- that is, the signal feeding the cutting system -- is already in analog form and can be auditioned directly. But in CD mastering, the original is in digital form, and stays that way until the time the disc is played in your home. In order to compare the original (digital) with the playback (analog), D/A conversion must occur at the output of the recording deck. And there's the catch. What D/A converter and audio section was *not* present in the chain that delivered the original signal to the CD. In other words, when we make a CD/master tape comparison, the "original" sound is being processed by electronics which are different from those used for the CD playback, *and the former may not be as good as the latter.* Professional recording equipment is notorious for having less than perfectionist quality audio circuitry and parts. That's why every recording studio that aims for the best sound customizes its tape decks. Some consumer CD players (Mission&Meridian) probably produce a better sound from CD digital than do the decks used to master those CDs. So it is more than likely that if HFN&RR were to repeat those tests today, the CD sound would emerge as the clearcut winner, and would actually be judged *better* than the "original tape". Under the circumstances, though, it is likely that such comparisons between the master and the consumer product are more reliable for digital recordings than for analog ones, because there are no mechanical transducers involved. Bad electronics can do some nasty things to digital sound, but they tend to have relatively very little effect on the spectral balance of the sound -- the balance between bass and treble, and the absolute high-end content. Thus, while we may still quibble over other aspects of CD sound, there is little doubt that what we here from a CD is *much* closer in spectral balance to the master tape than what we here from ananalog reproduction of the same recording. That is why I adopted CD as my "standard" for judging most aspects of the sound of analog sinal sources. Where CDs contrast consistently with what I hear from analog, I assume (on faith, you might say) that the CD sound is closer in spectral balance and low-frequency quality. If that CD sound is not "good*, I do not assume that the better analog sound is "right". Instead, I adjust the other components in my system -- the loudspeakers, in particular -- until the sound I hear from CD in the listening room is as close as possible to what I remember of live music. This then becomes my standard for evaluating analog sources. The sound I get from analog is of a very high standard, and it has very similar spectral balance to digital sources. The CD is still not what I consider to be *absolute*, but I do believe it is the closest approach to such an absolute that we're likely to find. It's certainly better than wondering wether the lovely sounds I get from some analog discs are the result of almost-perfect everythings in the chain, or merely of a fortuitous mating between countless gross system colorations all the way from the microphones to the loudspeakers.