Tuesday, July 29, 2008

Digital vs. analog for vinyl record buffs

Analog recording-- which is the source of most used vinyl sold at moneyblows books and music-- can be thought to essentially reflect the Victorian scientific imagination, in which sound is mechanically inscribed, rather than digitally encoded.

By contrast, the pitch, tone color, and loudness of a digital playback starts out as binary numbers intelligible to computer circuits. In other words, the presence or absence of an electric pulse (“1” or “0”) is detected and digitially converted in the original reproduction.

The waveform of the sound, as a human might hear it at this point, becomes a representation of the audio frequency, possibly encompassing more than half a million bits per second. For more than a quarter century now, this torrential bit stream has become audible when a digital recording is played back.

It all begins when a musical waveform is "sampled" at least 40,000 times per second. Each sample represents a point in time as the music unfolds. Then, the height of the sound wave at each of these 40,000 sampling points is numerically expressed. Together, these two factors accurately describe the sound wave so that it can be recorded as a series of numbers.

In playback, those numbers are fed into a device called a digital-to-analog converter which produces voltages corresponding to each number at precisely defined points in time. In this way, the digital signal is reconstituted as a waveform.

Once it is digitally encoded, the music’s fidelity is undisturbed—whether it’s on vinyl or CD, or played via a computer's own file or an internet stream, theoretically makes no difference.

A moment of digital silence—or an analogous very faint pianissimo, is preserved without tape or vinyl noise. An explosion of musical loudness needn’t be intentionally (though expertly) distorted for the putative convenience of the end user, or the delicate constitution of a record stylus.

In a digital recording, bass response is extended from 30 to 20 Hz to encompass the very lowest notes of the musical spectrum. Frequency deviation over the entire range from 20 to 20,000 Hz is reduced from ± 2 db to ± 0.5 db, resulting in clarification of tonal timbres and textures thanks to greater linearity in the crucial overtone range.

Dynamic range, i.e. the maximal span between loud and soft, is enlarged to 90 db, closely approximating the natural loudness range of live music. Distortion at maximum loudness shrinks from the traditional norm of 1% to an amount too small to be measured, resulting in the added clarity of loud passages. Finally, flutter and wow - those marginal wobbles of pitch that cause a sense of false vibrato in some conventional recordings - also reduced from the usual 0.050/0 to the point of unmeasurability.

A vinyl record, though, remains the manufactured product of its Victorian heritage—a representation of the musical waveform in inscribed (actually stamped) grooves. It’s necessarily imperfect compared with computer playback, and presents the listener with a Hobson’s choice of whether one should listen with digital ears or analog ears.

Ears are the definitive equipment for listening. The ultimate choice of digital or analog, I think, is cryptically (though oddly appropriately) laid out in the movie “Pulp Fiction,” when (I’m paraphrasing here) Uma Thurman asks John Travolta, “Do you spend your time listening, or waiting to talk?” Travolta hesitates for a moment and says, “I guess I spend most of my time waiting to talk…. But I’m working on listening.”

In listening there invariably is background noise, whether or not it disturbs the foreground intent. A truism of hearing loss is that the two eventually blend, so that the person suffering some auditory loss will say, “I can’t hear you,” particularly in a crowded room.
Using this standard, I don’t mind listening to the background noise in a vinyl record, until it gets so bad I might say to the music, “I can’t hear you.”

Digital techniques can fix that, too. People buy HD TVs so that can get better resolution of a lousy show. The greatest invention of modern culture, television, is about to be bumped off the analog spectrum as of February 2009. You are already being asked to give it up.

I have VHS tapes and records to play. Judge for yourself who is better equipped-- the digital only consumer, or the one the one who admits the imperfections wrought by Thomas Edison when he lit the known world.