SME 20/12 and 312S Tonearm Reviewed
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Clarity is the quality that most exemplifies SME's Alastair Robertson-Aikman, and on many levels. It's a property of the sound reproduction of his company's products, of the very instructions contained in SME owner's manuals, and - above all - it applies to Alastair's thinking. Had he ever decided to embrace the dark side, by going into politics or law, we would be living in a very different country, indeed. It's this clarity, in all of its forms, that is embodied on not one but two new products from SME, a company that is positively Quad-like in the rate at which it introduces new models.
And they are never introduced 'just for the sake of it.' Invariably, a new model arrives because AR-A had a brainstorm while tweaking his system, a vision that results in some canny device which his éclaircissement will render so obvious that you can only marvel at the ingenuity. This time, the two products are so closely interrelated that the words 'chicken' and 'egg' might spring to mind. But, in fact, the first to arrive was the 312S tonearm.
Alastair thus had an impetus for pursuing once again the benefits of 12in arms, in the form of ultra-light, ultra-strong magnesium; you can stand on a 9 in SME pressure die-cast magnesium tone arm tube and it will not bend nor break. The benefits of a mere three inches? Primarily the reduction in tracking error that occurs because the arc that the cartridge follows in a 12in arm is closer than the arc of a 9in arm to the ideal straight line of the LP cutting head. It's geometry so simple that even I can understand it. And if you want numbers, Reg at SME calculates that a 12in arm is 27.23 percent better than a 9in arm for both angular error AND distortion.
So, while some of us have happily employed the 12in Ortofon, the SME 3012, M2-12 or even the regular 312, or other 12in arms, we have had to deal with a trade-off: substantially reducing the distortion due to the tracking error of a 9in arm [see chart], while having to deal with the inevitable increase in the effective mass of the longer arm. The arrival of the 312S, however with its arm tube made entirely of magnesium, enables the increase to be sufficiently off set and no longer an issue.
AR-A notes that, 'The tonearm fitted to the 312S, including the headshell, weighs 48g. This compares with 75g if it were made in aluminium, making it unsuitable for cartridges of normal compliance, that is, between 20 and 25cu.' So now we have a 12in arm, probably the lowest mass 12in tonearm ever made, that is quite comfortable with the vast majority of cartridges in the 'normal' weight range of circa 6g-12g.
Other benefits that are provided by the 312S include a smaller excursion of the counterweight, higher contact loading of the bearings, all must have some clearance! greater length in which the acoustic signal generated in the arm can dissipate, a reduction in susceptibility to warp/wow, and a greater range of movement when adjusting VTA. So it's not just the reduction in tracking error that make 12in arms so appealing, once they're free of concerns about effective mass.
SME merged elements of the Series V, including its arm tube and damper, with the counterweight assembly and detachable headshell of the Series 300 to create the 312S. Increasing the Series V's arm to 12in status involved fitting an extension to the basic Series V tube, using pressure fitting and an adhesive, the arm then finished entirely in black.
Which begged the question that led to a second new model: To what can it be fitted? The SME 10 was out, because under no circumstances would AR-A countenance an arm-board extension floating out in the breeze. (Of course, any extension SME would fashion would be as robust as one could possibly want, but Alastair does not approve of arm-boards supported only at one point.) And the SME 30/2? Because it was conceived as a cohesive source component with the Series V, and because its performance is so far 'out there' as to obviate any need for improvement, that combination was left alone. For the time being, at least.
SME had introduced new power supplies for the entire range in late 2005*, so the turntables were all 'up to date.' There was, however, a substantial price difference between the SME 20/2 and SME 30/2. Adapting the former to cope with a 12in arm presented a perfect opportunity to fill the gap. So AR-A chose the middle model, the SME 20/2, as the candidate for what he wryly calls "the long wheelbase version."
Broadening the 20/2's chassis to accommodate a 12in arm resulted in a model deserving a new model designation: the 20/12. With the new power supply in the mix, added to the increased chassis size, the longer arm, and a larger platter than the 20/2's, SME's efforts produced what is, effectively, a new design, rather than a mere refinement. Even the chassis mass was increased, to offset any decrease in rigidity due to the extra width.
Quite unexpectedly, a non-sonic benefit emerged: the new look of the 20/12 emerged as a cosmetic makeover. As one visitor to SME noted, it looks more 'right' than the standard, almost square '20, as if the deck had been waiting all along to have its width extended. Its new proportions can be likened to those of the 20/2's, as 16:9 widescreen video images are to 4:3. But it also means that owners will need space for a record spinner with a footprint of 375x520mm, compared to the compact 320x420mm of the 20/2.
Having duly prepared just such a space, on a robust GM Accessori table, I fed the SME 20/12 and 312S into Audio Research and AudioValve phono stages. And thank goodness for detachable headshells. The one made for the 312S bolts utterly securely to the tube, so, please, let's not even re-open the fixed-vs-detachable debate. I appreciated the ease with which I could move from the Transfiguration Orpheus and Blue Angel moving coil cartridges I had been using in the SME 30/2 with Series V arm.
While I was expecting minor differences, I was certainly not ready for the slight change in character that will making choosing between the 20/12 and 312S package and the flagship 30/2 with Series V somewhat easier. It's obvious that direct comparisons are almost impossible to make because the 312S has no direct 9in equivalent, and the 30/2 doesn't exist in a long wheelbase edition. So I stopped worrying about pecking orders and just sat back to revel in qualities that were new to my ears. All of my 12in arms are of the Jurassic variety, and work well only with massive moving coils of the Ortofon SPU variety, and they're mounted on aged idler wheel decks, so the reduction in tracking error was a new sensation. And I've been living with an SME 30/2 with Series V arm for years; the sound of it is as engrained in my consciousness as that of my wife's voice.
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