THERE is something admirable about people with a passion for forms of media that have fallen by the wayside—black-and-white films, vinyl records, silver-halide photography, lithographic printing and other relics of analogue expression that have been superseded by digital equivalents. In their continual search for caches of vintage stock, and their willingness to spend large sums buying or restoring legacy equipment, these connoisseurs keep alive priceless technologies that could too easily be lost. In so doing, they foster numerous specialist firms dedicated to technical excellence in their field.
A case in point is the growing enthusiasm among audiophiles for monoaural recordings that date back to the early days of the LP album before stereophonic sound took hold in the late 1950s. Collectors talk of mono’s concentrated sound, compared with stereo’s more diffuse audio image. To discerning ears, a mono record—played on a high-end turntable with a well-damped and carefully matched tone-arm and cartridge (stylus)—offers an audio experience next only to hearing the original performance live.
It is certainly true that even dusty old mono records can deliver greater acoustical punch, while being significantly quieter in silent passages, than a stereo recording. They track with few of the ticks and pops that characterise even lightly used stereo LPs. Enthusiasts swear the higher acoustical “resolution” of a mono recording allows individual instruments to be discerned more clearly, despite the paucity of location cues in the sound picture. Music lovers talk of them being simply “more convincing”.
All of which may well be true. It should be remembered, though, that when LPs first appeared, performers were the key arbiters of the quality of the recorded music. Given the artistic opportunities of the new long-playing medium, LP records were seen more as historical documents for conveying the spontaneous image in a performer’s mind—mistakes and all—for a broader audience and future generations to appreciate.
That all began to change with the marketing onslaught unleashed by stereophonic sound. Henceforth, it would be the record producers, not the performers, who determined the acoustical outcome. And they did so mainly for commercial reasons, rather than for artistic ones. Mistakes were engineered out of a recording with edits from numerous retakes. A perfect (some say too perfect) product was then packaged for mass appeal. No wonder unadulterated mono records from a more innocent age resonate so profoundly with enthusiasts.
Yet, perhaps, full credit is not given to the improvements made in pick-up technology since the majority of mono records were pressed more than half a century ago. Over the years, stylus designers have tinkered with every pick-up mechanism imaginable. Early models used piezo-electric crystals, which converted vibrations in the groove into an electrical voltage. Unfortunately, the crystal’s non-linear output tended to distort the sound.
The ceramic cartridges that followed had greater compliance (ie, offered less resistance to movement) and could therefore follow the modulations in the groove more accurately without jumping out or causing distortion. Their higher compliance implied lower tracking forces, which translated into less wear of both the stylus tip and the record itself. Without the ceramic cartridge, stereo would have been a long time coming.
The cheap magnetic cartridges of the 1970s heralded yet further improvements, including a much smoother frequency curve. Both the moving-magnet and its moving-coil relation rely on electromagnetic induction to translate the movement of a cantilevered diamond stylus into an electric signal induced in a set of pickup coils. In another variant, known as a moving-iron pick-up, a stationary magnet is used to magnetise the cores of a set of coils, while a tiny iron bar or disc attached to the end of the stylus uses the vibrations to vary the air gap between itself and the coils, producing a voltage that is proportional to the sound encoded in the groove.
Popular stylus makers like Grado and Ortofon continue to produce a range of magnetic pickups suitable for mono records. Their prices vary from $90 to over $1,200. Meanwhile, Lyra produces some of the best mono cartridges around, with prices of $3,500 and up.
As one might expect, there is a world of difference between playing an old mono record on a gramophone built in the 1960s compared with listening to it on equipment available today. Also, some of the vinyl used for early LPs was little better, in terms of surface noise, than the shellac and other coatings used for 78-rpm records.
For his part, Babbage plays his precious collection of Elgar uniquely conducting his own works—the first important composer to take the gramophone seriously—using a fairly decent stereo setup. EMI made the original 78-rpm recordings (mostly during live concerts, but some at Abbey Road studios) between 1926 and 1933. The historical collection was remastered as a set of five LPs in 1972. The boxed set is clearly marked for mono as well as stereo playing.
One day, Babbage promises himself a proper mono cartridge. But given their astronomical price, they are hardly an impulse purchase. There are, of course, cheaper cartridges, which may be more appropriate for his battered ear drums. Whatever, it will be interesting to note the differences between mono and stereo playback, even though the Elgar pressings are not, of course, mono discs.
What to expect from mono generally? Bear in mind that original mono records were never designed to be played on a modern stereo turntable, with a tone-arm counter-balanced to give just a few grams of tracking force, and a carefully matched elliptical diamond pick-up rather than the spherical (ie, fatter) sapphire styli of the past. The thinner stereo pick-up of today rides deeper in the groove, below where most of the wear and surface noise occurs. It should be no surprise, then, that vintage mono LPs sound as good as they do on modern equipment.
With a mono cartridge, they should sound even better. For a start, the groove in a mono record is cut like a snaking, spiral trench. The modulation occurs laterally, with no vertical motion whatsoever.
By contrast, a stereo record uses a V-shaped groove that is modulated in the vertical as well as the horizontal plane. The left-channel’s modulations are encoded on one of the groove’s 45º walls, and the right-channel’s on the other. Dirt and damage on old records normally cause the stylus to jump up and down. Thus, a mono pick-up, which suppresses vertical motion, can eliminate many of the unwanted ticks and pops that a stereo pick-up will faithfully reproduce.
At this point, audio purists usually have a heated discussion about what makes an ideal tone-arm—the articulated component that holds the pick-up over the groove as its tracks from the outer to the inner part of the disc. Some even argue that the tone-arm contributes more to the overall quality of the sound than any other component.
Such arguments go over Babbage’s head. Suffice it to say that each of the mechanical components which comprise a hi-fi system—from deck to platter, drive, bearings, arm and cartridge—have to collaborate in a way that ensures all extraneous vibrations are isolated, or at least sufficiently damped, to prevent any accumulation of resonances from affecting the sound plucked from the groove by the stylus and delivered to the electronics.
That said, tone-arms suffer from two mechanical defects which present headaches for designers. One results from the fact that the stylus exerts a frictional force that is tangential to the groove. As this force does not intersect the pivot point of the arm, a clockwise moment is exerted on the stylus, which can cause it to skate across the disc. The other problem occurs as the arm sweeps in an arc across the disc, causing the cartridge to become offset at a slight angle to the groove. This results in different forces being exerted on a groove’s two adjacent walls. In stereo records, the left and right channels then respond with different intensity and phasing.
Great pains have been taken to cancel the skating force and eliminate the cartridge-angle error—none of which has been wholly successful. The linear turntable, for instance, attempts to solve both problems simultaneously. In this design, the arm does not pivot, but moves radially across the disc, allowing the stylus to remain tangential to the groove throughout its journey from the outer edge of the to the centre of the disc.
Having a stylus replicate in this way the linear tracking motion of the recording lathe used to cut the original master record is hugely attractive. In doing so, it would reduce wear while ensuring the nearest thing to perfect reproduction. Unfortunately, the complexity and cost of developing linear-tracking systems defeated the likes of Sony, Yamaha, Pioneer and, in the end, even Bang & Olufsen. Besides, such innovations arrived just as the Compact Disc was set to disrupt the whole of the hi-fi business.
Most turntable makers these days simply put up with the offset-angle issue, while adding springs, weights or magnets to the tone-arm to counteract the skating force. It is not ideal, but the approach works reasonably well. As is invariably the case with audio equipment, the proof is not so much in the engineering as in the listening.
And a veritable listening treat is in store for mono addicts everywhere. From September 8th Apple (the Beatles’s music label, not the computer company which was formed much later) will start releasing individual mono LPs, and subsequently a boxed set of all 14 albums that include every recording the Beatles ever made.
The new mono release is not to be confused with the disappointing set of CDs (“The Beatles in Mono”) produced in 2009 from digital masters. For next month’s release, EMI engineers at Abbey Road remastered the tracks from the original analogue tapes. Amazon is taking pre-orders for the limited-edition set priced at $375. Babbage believes that is reason enough finally to splurge at least that much again for a mono cartridge. Time to find out what all the fuss is about.
