Where We Are & How We Got Here Page 2
Of course, today's best cartridges and preamps (and 'tables and arms) can make a disc sound almost exactly like its source, whether that source was an analog or digital tape, or a direct-wire hookup from the microphones.
For almost a decade after the stereo LP appeared, virtually every new release was distributed in two versions: stereo and mono. This provided ample opportunity for comparison—the stereo release always had considerably less dynamic range than its mono counterpart.
There were several good reasons for this. The most important, of course, was that stereo cartridges had even worse trackability than mono ones. Another contributing factor was that stereo disc cutters, being less efficient (at that time) than mono cutterheads, required more amplifier power to drive them to comparable levels, and were prone to burnouts if pushed too hard, particularly at high frequencies. The vulnerability of cutterheads was exacerbated by the already rampant practice of hyping high frequencies over and above RIAA requirements (see "Clout," below) to add that brilliance that mainstream-audio magazine reviewers once wet their pants over. (One small record company used to brag privately about the number of cutters they wiped out. This was offered as proof that their records had more highs than anyone else's.)
During subsequent years, improvements in playback cartridges and recording technology gradually upped the attainable dynamic range from discs until, today, it is both possible and practical to cut a disc from a Dolbyed (or dbxed) master tape with, in most cases, no volume compression whatsoever.
The history of background noise is the greatest success story to come out of audio. Noise elimination is, in fact, the only aspect of music reproduction which has seen dramatic and progressive improvement through the years, without any of the periodic setbacks (in distortion, for example) that usually accompany format changes. Shellac was quieter than Amberol (the trade name of the quietest material for mass production of cylinders), vinyl was quieter than shellac, open-reel tape was quieter than its contemporary vinyl, and compact disc has finally gotten rid of every last vestige of background noise. You've got to admit that that's progress, regardless of how you feel about other aspects of CD performance!
The late 1950s and early '60s saw the introduction of two kinds of super-fi tweeters: the push-pull electrostatic (footnote 5), and the ionic or "blue-glow" tweeter. Because neither system relied on the stiffness of a diaphragm to impart sound waves to the air, they were freed from the constraints of moving mass which limited other tweeter types to a high-end range of 15 to 18kHz. Both were capable of reproduction to well beyond 25kHz, but were also costly, and not impressively reliable.
Apart from the reinvention of the metal-dome and metal-ribbon drive-units, there have been no new tweeter drive principles introduced since then. There have been, however, a number of developments in materials and production technology which have allowed the lowly dynamic tweeter, with its modest cost and superior reliability, to equal and, in some cases, surpass what was previously available only from electrostatics and plasma tweeters. Use of extremely light, highly-damped plastics, combined with metal-deposition techniques, have made possible dynamic tweeters whose diaphragms have the almost ideal combination of stiffness and lightness.
Some of this technology has trickled down to the production of inexpensive dome tweeters, whose HF range and smoothness rivals that of the best money could buy in 1962. State-of-the-art high frequencies are, in truth, little better today than they were 25 years ago, but average HF performance is infinitely better.
Deep bass reproduction has been available to anyone with the money to pay for it and the space to accommodate it since the mid-1930s, but there were few who could afford either. In '62, deep bass called for a huge enclosure or scads of amplifier power, but the quality of bass attainable either way was not very good. Good reproduction of deep bass at levels I thought adequate was possible then only from very large horn-loaded woofer systems.
Footnote 5: Although every audiophile knows this term, few understand what it means. It refers to a change in mechanical or electrical state brought about by the simultaneous but complementary action of two opposing influences. Thus, in a push-pull amplifying stage, the passage of a rising signal voltage involves a current increase in one half of the push-pull circuit and a current decrease in the other half. In a push-pull electrostatic loudspeaker, diaphragm motion in one direction is the result of its attraction to a fixed screen on one side, and repulsion from a screen on its other side.