In our last installment, we saw the beginning of the transition from monaural records to single-groove stereo records. Even today, software changes often require similar changes in hardware--- we've discussed how the change from "coarse groove" shellac 78 records to microgroove vinyl LPs required reductions in the stylus size and tracking force in order to play the new, softer vinyl records without butchering them. When LP records further changed from mono to 45/45 stereo, the cartridge, arm, and to a lesser extent, the turntable, had to change as well.
Let's think about that for a second. With mono records the groove is of constant width and depth, the v-cut is somewhat variable but always near 90 degrees, and the groove is lateral cut, meaning stylus motion is side-to-side. If you imagine the motion of a Foucault pendulum swinging back and forth, and imagine the turning record as the analog to the Earth's motion---that describes the tracking of a lateral cut record.
--Sort of. I'm afraid that that illustration might obfuscate the issue for some, rather than clarify it. Perhaps this presentation by Ortofon will help.
Anyway: a mono record only has one signal contained within that groove. The single groove stereo record has two synchronized signals contained within the groove, cut at +/- 45 degrees. While the stylus of a mono cartridge only has to move side-to-side, that of a stereo cartridge has to move up and down (the so-called "hill and dale" cut, as used on early Edison discs) in addition to the side-to-side motion, and be able to generate the two signals separately from one another---as much as possible. An extremely important specification is that of channel separation---in very simplistic terms, the higher the number in dB, the better will be the stereo image.
Exactly what "stereo image" means, is open to debate. Many of us were subjected to cheesy Stereo Spectacular demo records featuring a steam train going from one side of the room to the other, or the annoying pah-DUNK PAH-dunk of a ping-pong match, with the ball noisily bouncing from speaker to speaker. The real trick of a good stereo recording is of course depth, which helps to present the sense of being in a concert hall, rather than just hearing a flat image where everything is the same distance from the listener.
As home stereo rigs gained popularity, folks showed off those rigs to their neighbors using the biggest, splashiest recordings they could find---and that called for cartridges that could track those challenging records. Mainstream cartridge makers like Shure, Stanton, Empire, and others did what they could to create impressive specs of tracking ability. In the late '50s we saw cartridges becoming smaller and lighter, and compatibility with tonearms became more important than ever. 1959 saw the launch of the Model 1 pickup arm from SME; for most audiophiles and for many years, variants of this arm would be viewed as the standard.
By the mid-'60s the SME Model 1 had morphed into the 3009, which Gordon Holt briefly reviewed for Stereophile in 1965; note also the accompanying piece on the 3009 II by British writer/engineer John Wright, whose reviews were models of precision and detail.
In 1967, Shure released a disc that was a useful guide to set-up, a challenging test record, and a brilliant marketing schtick---all in one. The Audio Obstacle Course first appeared alongside the "Supertrack" V-15 Type II cartridge, and new editions of the record accompanied every subsequent version of the V-15. In the competitive world of hi-fi nerddom, the disc provided rival turntable set-ups the equivalent of timed laps at a racetrack; your "Corvette" could challenge your friend's "GTO", and could quantify the tracking ability of each.
By the time I became aware of audio in the late '60s, the hi-fi world as seen in Stereo Review, High Fidelity and Audio, offered only a limited number of choices for record playback gear. The top dog playback system was the Thorens TD-125 with SME 3009 arm and Shure V-15 whatever. The garishly gold Empire tables were largely seen only in Empire ads; I never, ever saw one in a dealer's store. While apparently well-built, they exuded a somewhat homespun air compared to the TD-125's spare elegance and restraint. Record changers? Dual was it; Garrard and Miracord seemed second-rank, at best. Cartridges? The holy trinity were Shure, Empire, and Stanton/Pickering (similar models produced by different divisions of the same company). The exotic Danes were out there, somewhere: Ortofon, still faithfully making moving coils alongside their less-expensive moving magnets, and the oddly-cylindrical B&O cartridges. EMT? Maybe in European radio stations. The stations I worked at all had cheap Shures.
During this period, I was completely unaware that Stereophile magazine was out there---occasionally. VERY occasionally. It was that annoyingly-irregular publishing schedule that drove Harry Pearson to start The Absolute Sound.
With the arrival of TAS, the world changed for lone audiophiles out in the wilderness, as I was. Without overstating the case---the impact of TAS was almost like the arrival of the internet, a generation later: suddenly, there were all manner of wonderful toys being featured, discussed, reviewed, analyzed....Record playback? Think Supex, ADC, Decca, Stax, Grace, Grado, Linn, Ariston, Fidelity Research---and that was just the beginning. With the arrival of TAS and that beautiful creation at the top of the page, the world of the American audiophile changed forever.
...and my life would never be the same.
More, in the next issue of Copper.