Turntables, Arms & Cartridges

Although Vertere's Tri-Point Articulated (TPA) bearing precludes classifying the SG-1 PTA as a purist 'uni-pivot', it is still a variation on the theme in that it rests on a single point – the basic definition of such tonearms, as opposed to those which use a more stable gimbal arrangement. However, by settling its stainless pivot in the centre of three precision silicon nitride balls, Vertere's TPA bearing brings easier azimuth settling, levelling and greater stability than most uni-pivots, many of which rock, sometimes alarmingly, on their single-point support.

Why, then, would designers opt for uni-pivots? The purist's excuse is the alleged lower friction; the cynic's excuse is lower production costs. As there are good and bad arms of all types, the truth lays somewhere inbetween. The SG-1 PTA is a perfect example, like Graham Engineering's Phantom Elite [HFN Apr '13], of a uni-pivot with stability. Graham uses a magnet as a stabiliser, while other arms have tried myriad Heath Robinsonian solutions, including fluid damping.

Uni-pivots have been around for as long as there have been flat records, with Stromberg Carlson's RA498 dating back to the 1950s, while numerous classics over the years have seduced audiophiles, including yours truly. These include the Decca International optimised for Decca cartridges, Grace's G-940 and much-loved G-714 wooden uni-pivots, arms from Mayware and Hadcock, the refined UltraCraft AC-30 and too many others to recall.