THE URGE TO TWEAK

We are now in the eighth year of the CD era, but despite very significant advances in digital recording technology, and better understanding among recording engineers of the special demands of the digital audio mediums, CD-bashing and a general condemnation of digital sound still persists among the die-hard advocates of analog audio.

I have addressed this phenomenon before, but while these digiphobes are a relatively small group, they are very vocal. Their self-proclaimed superior aural sensitivity and acuity enables them to hear anomalies and artifacts in digital sound and CDs which are simply not perceived by people with "normal" hearing faculties. There are a considerable number of people who are audiophiles. This is an honorable estate, descending from the "hi-fi nut" of the early days of audio. An audiophile is as a person who most diligently and unrelentingly pursues the goal of reproducing electromechanically, magnetically or optically recorded music with the highest degree of fidelity to the live sound. Audiophiles do not eschew objective scientific measurements of sonic parameters, but few would deny that subjective evaluation of sound qualities is the predominant factor in their sonic perceptions.

Over the years, audiophiles have been ridiculed, reviled, and rejected as negligible in the general scheme of the recording and music business, or merely tolerated for their aberrant behavior. For some time, audiophiles have actually achieved a certain degree of respectability, as the general audio/record market has become aware of advances in technology that approach audiophile expectations.

Digiphobes are a sub-species of audiophile and, of course, are certainly entitled to their opinions. It's easy to be tempted to simply dismiss them, and, indeed, their notions are not about to disrupt the audio industry. Nonetheless, they have found eloquent spokesmen in the so-called "underground" press. These publications can be informative and interesting, as long as they don't wander off into pseudoscience with wholly subjective conclusions.

I think I'm a pretty tolerant man and so are most of my friends and colleagues in professional audio. This is not said with any arrogance or smugness. If these protagonists of analog sound prefer the vinyl LP, that's just fine. But what many of us find irksome is the relentless "put-down" of all things digital-with scant regard for the technical validity of their arguments. Couple this with a nose-wrinkling condescension towards those insensitive clods who actually like CDs and digital sound! By theft very nature, these publications have a major problem. By their own admission, the analog vinyl LP is in a precipitous decline, which will ultimately be terminal. Thus, very few recordings are being issued on vinyl LPs, and they must, perforce, discuss and review CDs and digital audio equipment. There is some grudging respect for the sound quality of some CDs, but a qualifying comment always follows, typically: "While the sound of this CD is quite good, it just doesn't have the musicality and natural warm ambience of the best analog LPs." As noted, everyone is entitled to have fun and enjoy his hobby. Some people are avid collectors and traders of baseball cards or beer bottle caps.

Don't turn me on, but more power to those who enjoy these things. So it is with the devotees of vinyl phonograph records. So much was involved in the playback of LPs and the general pursuit of hi-fi sound that the audiophile hobby really flourished. In the 1960s and 1970s, the "tweaking" of phono playback equipment was in full flower.

Think about it: Playback of a record involved a routine which, in its most convoluted aspects, was almost akin to a mystical rite. The record was first cleaned in some fashion, then sprayed with some supposedly anti-static agent or zapped with an ion gun. The special anti-resonant headshell was equipped with special Litz wire connectors to the cartridge terminal. The headshell might be equipped with a clip-on device that used radioactive Polonium to reduce static changes. Then there were the magic record platter mats.

Exotic materials were employed in these mats in an effort to suppress mechanical resonances in the LP. There were myriad other tweaks applied to LP playback, to say nothing of the unending search for LPs with minimum warp and, hopefully, reasonably quiet surfaces. There were, of course, the special audiophile pressings which were made with loving care. The ultimate was perhaps reached with JVC's "UHQR" records which commanded very high prices for that era.

There is no question that there were many useful tweaks along with a lot of non-useful stuff. They were part of the fun, and undoubtedly there is resentment towards the CD because it is really not amenable to tweaking.

Undeterred by the digital technology of the CD, and finally coming to the realization that CD will be around for quite a while, the digiphobes are now trying to tweak CD playback to correct some of its "inherent defects." To say that most of this CD tweaking is "wild and wooly" is to put it mildly.

I have kept silent about this tweaking, but it has now become such absurd hocus-pocus that I feel compelled to offer some comments. I am not making these comments as if I'm coming from on high. Rather, I have carefully researched these various CD tweaks and have consulted with experts and authoritative people, in the purely scientific and CD-manufacturing communities, as to the possible validity of these tweaks.

There is no question that many of the CD tweaks that have been employed stem from a basic misunderstanding of the digital technology of the CD medium. Many audiophiles freely use such CD jargon as bits, sampling rate, quantizing, jitter, and dither without really knowing what they mean.

Recently, there have been some articles appearing in various audio publications, which specifically address some of these CD tweaks. In the January 1991 issue of the British journal Hi Fi News and Record Review, digital audio expert John Watkinson writes in his article "Simple Sampling" about the fallacies of various CD tweaks in an informative (and often amusing) article: If the binary values leaving the error correction system of a CD player are numerically identical to those on the master tape which was used to make the disc, then there has been no loss of information, and therefore the digital circuitry of a well-engineered CD player has no quality. Since this is a fact, we must look elsewhere to find the factors which determine the quality in a digital audio device, and we will find them in the conversion processes .... The sound quality of a well-engineered digital audio recorder is independent of the medium and the transport and depends only on the quality of the converters ... We can now draw some interesting conclusions about the accessories (tweaks) which are available for CD players. Special cleaning fluids will not improve the sound quality of a mucky CD more than washing-up liquid [detergent] .... Using bizarre substances on discs could actually cause physical damage. The Armor-All saga is a good example of this kind of nonsense.

For those who are not familiar with Armor-All, it is a commercial product used, among other purposes, to clean and protect vinyl roofs on cars.

Rubbed on CDs, it was supposed to "dramatically improve the CD sound" according to the tweakers. What it did was to cause delamination of some CDs! I checked with the engineers at the Sony CD pressing plant in Terre Haute, Ind., and they said they loved Armor-All because it produced a lot of sales for replacement CDs. They also said that if CDs treated with Armor-All were played for five or six hours, heat build-up could cause the highly volatile Armor-All to "outgas" and could destroy the laser pickup diode! Watkinson also states that "Damping rings do not improve the quality of CD replay. Drawing with green felt-tip pens around the edges of a disc will not improve the sound quality." While it is true that in most CD players the unsupported edge of a CD can cause vertical flutter, damping rings cannot reduce this flutter because they are not accurate enough in concentricity, and, in fact, impart enough eccentricity to the CD to cause far more of a problem than edge flutter. As for the green ink around the perimeter of a CD, this is supposed to suppress internal reflections in a CD, which are caused by the laser beam. I had duplicate CDs of three different recordings. One set I left untreated; the other set was painted as per instructions. After many comparisons on several different CD players, I heard absolutely no difference in sound quality. I checked with a friend of mine who was a research physicist at Hewlett-Packard. He is also heavily into high-end audio. He stated there was absolutely no electronic or optical phenomena resulting from this treatment that would affect digital signal output or sound quality.

One of the newest tweaks is cryogenically treating CDs! In essence, over an eight-hour period, the CDs are reduced to-320° F (the temperature of the liquid nitrogen used in the cooling chamber) and over another eight hours slowly restored to room temperature. Because CDs are injection-molded by means of heat and pressure, this supposedly sets up internal stresses and higher mechanical resonances in the CD. The cryogenic treatment supposedly changes the lattice molecules in the polycarbonate from which CDs are made, relaxing the molecular bonds, with subsequent lowering of mechanical resonances, all of which ultimately lessens the jitter output from the player. I checked this out with the Sony CD pressing plant engineers, and with two friends who are physical chemists. While they say there is an element of truth in the relaxing of molecular bonds, it is insignificant and, from the digital viewpoint, would not be audible.

All sorts of other tweaks purportedly improve CD sound, but there are so many other variables in an audio system that have far more influence on the sound. As P. T. Barnum said: "There's a sucker born every minute."

(adapted from Audio magazine, Apr. 1991; Bert Whyte)

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