SME Model 12A Turntable Lab Report

Lab Report

The Model 12A's platter, bearing and motor are clearly derived from the Synergy deck [HFN Mar 19], as is the MOSFET-based PSU/speed controller. Once again, the 4.6kg alloy platter spins up within four seconds while the wow and flutter, and rumble, specifications are as close to that of the Synergy as production tolerances might predict. So, our sample was also a mere –0.05% adrift in absolute speed while the peak wow remained at a respectably low 0.015% [see Graph 1, below]. Peak flutter was actually slightly lower at 0.030% (versus 0.035%) and visible here in a reduction in amplitude of the shoulders at ±20Hz. The same, or similar, 19mm chrome-steel spindle and bearing registered a mere –71.5dB through-groove rumble, improving to –72.7dB with the record clamp in place. Once again, the through-bearing rumble is quieter still at just –74.7dB (DIN B-weighted).

The partnering 309 tonearm, despite not being a 'one-piece' tube/headshell, is arguably a simpler design than either the Synergy or Series IV [HFN Jun '10] – the adjustment and locking for the underslung counterweight, for example, lacking those convenient 'finger controls'. However, the tapered tube, bearing yoke and counterweight rail are all still fashioned from a single magnesium alloy die-casting, and even with the robust locking collar for the headshell, the effective mass is still just 10g. Comparing the resonant spectra [waterfall, Graph 2] is intriguing – like the SME IV and Synergy, the first bending mode occurs at around 150Hz but the principal higher-Q harmonic/twisting mode occurs at a higher (midrange) 680Hz here. So the 309 will have a different 'tone'... Finally, as expected, the pre-loaded bearings offer almost zero friction and no detectable play. PM


Wow and flutter re. 3150Hz tone at 5cm/sec (plotted ±150Hz, 5Hz per minor division)


Cumulative tonearm resonant decay spectrum, illustrating various bearing, pillar and 'tube' vibration modes spanning 100Hz-10kHz over 40msec

Turntable speed error at 33.33rpm 33.32rpm (–0.05%)
Time to audible stabilisation 4sec
Peak Wow/Flutter 0.015% / 0.030%
Rumble (silent groove, DIN B wtd) –71.5dB / –72.7dB (with clamp)
Rumble (through bearing, DIN B wtd) –74.7dB
Hum & Noise (unwtd, rel. to 5cm/sec) –60.1dB
Power Consumption 5W (<1W idle)
Dimensions (WHD) / Weight 370x178x350mm / 25.9kg
Price (with arm) £7949
SME Limited
Supplied by: SME Ltd
01903 814321