December 2008

The Arm Chair vs. The Listening Chair

  I recently had an e-mail exchange with a long-time reader who encouraged me to immediately abandon in TAS all coverage of turntables and LP-playback products. The reader thought that TAS should use those pages to spearhead the promotion of high-resolution digital audio on Blu-ray Disc. (The reader is a world-class expert in his own field for whom I have tremendous respect.)

I'll discuss high-resolution digital in a minute, but I must first recount the reader's argument justifying his call for TAS to repudiate vinyl. He cited a litany of technical flaws inherent in LP playback that, in his view, warranted the immediate death of vinyl (the subject line of his e-mail was "Vinyl Records RIP"). These flaws included tracing error, skating, rumble, dirty records, and poor pressing quality of new vinyl. He also asserted, based on something he'd once read, that the playback stylus shaves off high-frequency information from the groove walls during the first play. This reader, incidentally, had stopped listening to records when the CD was introduced.

The same day I received this e-mail, another reader sent me an article from the July 2008 issue of Popular Science that began "Sorry, vinyl aficionados, but CDs most accurately capture the clarity of musical performances." The author cited the technical limitations of vinyl to support his argument (sound familiar?) and then suggested that CD was obviously superior because "the mathematical data encoded on a CD... is a nearly exact representation of the original sound."

The first piece of faulty logic behind these arguments is the assumption that any format with the theoretical flaws of the LP must sound bad. The second is that because CD doesn't suffer from vinyl's obvious shortcomings, it must sound better.

It's easy to visualize all the things that can go wrong when a chip of polished diamond is dragged through a piece of plastic containing a physical representation of the analog waveform. The whole affair seems exceedingly primitive and fragile, particularly when compared with the robustness of digital media. It's not so easy, however, to visualize the distortions introduced by slicing the continuously variable analog waveform into discrete units, representing each slice's amplitude with a number, and then making the whole thing into music again.

Digital audio appears to be cut-and-dried-perfect in theory, but the devil is in the implementation. In practice, turning a series of numbers back into a musical waveform is akin to trying to turn hamburger back into steak. I could cite the time-domain distortion created by digital filters, quantization error, jitter in the A/D and D/A conversions, non-linearity of ADCs and DACs, and the fact that distortion increases as the level decreases, thereby destroying the exceedingly fine details that contain the timbral and spatial cues vital to creating a sense of musical realism.

But the underlying flaw in all these arguments is the belief that one can judge the sound quality of a format from one's arm chair, a priori, simply by imagining the degradation introduced by the types of distortions inherent in each format. Linn founder Ivor Tiefenbrun said it best: "If you haven't heard it, you don't have an opinion." I asked the reader who called for an end to vinyl coverage in TAS if he'd heard a first-rate turntable lately. He hadn't. I suspect that the author of the Popular Science article hadn't either.

Vinyl has its flaws, but in my experience, those flaws seem to "ride on top" of the music. Consequently, they are easier to overlook than digital's flaws, which are "woven into" the fabric of the music. CD-quality digital audio has a synthetic character that permeates instrumental timbres; one has a harder time separating the distortion from the music. Where, in the respective lists of technical distortions of the LP and CD formats, do we find the experiential musical consequences of each format's particular distortions?

Notice that I said "CD-quality audio has a synthetic character." Digital audio isn't fundamentally flawed; it just seems that way because we've largely experienced it through the Compact Disc, a format whose specifications were frozen in the late 1970s. I've been listening for the past two weeks to Reference Recordings HRx files at 176.4kHz/24-bit played from a no-compromise PC-based music server (no hard drive, no fan) through the Berkeley Audio Design Alpha DAC. I'll have a full report in the next issue, but in the meantime, I can say that what I'm hearing bears no relationship to CD sound quality, and is in fact reminiscent of a live microphone feed. And that opinion wasn't reached by considering high-res' superior specs, but by a method that has no substitute — spending time in the listening chair.