Technics SL-Q303 turntable Lab Report

Lab Report

This fully-integrated turntable may have been launched after the SL-150 motor unit [HFN Oct '15] but our figures suggest it was perhaps not quite as robust. Nevertheless, as top dog in Technics' 'Front Control' series the SL-Q303 is still extremely capable. The diecast platter is brought up to speed within two seconds by a ('ultra low speed') DC motor while an internal 4.19MHz crystal is the source for the oscillator/clock that maintains its fine ±0.07% absolute speed accuracy. Wow and flutter is also usefully low at 0.02% and 0.04%, respectively, while the ±15Hz sidebands [see Graph 1] appear as a cluster of peaks on the rumble spectrum. So the SL-Q303 is not quite as silent as the SL-150 – its through-bearing (through-spindle) rumble is about 5dB poorer at -67.1dB (DIN-B wtd, re. 1kHz/5cm/sec) although the through-groove figure is only 3dB off at -66.1dB.


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

The partnering S-shaped 9in thin-walled alloy tonearm features a lightweight detachable headshell and its overall effective mass of 8g makes it an ideal match for the high-ish compliance EPC-U25 MM cartridge that was originally supplied. S-shaped arm tubes do not bend or twist in quite the predictable fashion of 'straight' tubes and this is reflected in the modestly complex cumulative resonance waterfall [Graph 2]. This indicates main modes at a low 50Hz and 100Hz with harmonics and/or torsional modes at 270Hz and 540Hz, the latter decaying quite quickly. Our sample was in excellent condition with the gimbal bearing exhibiting no free play while offering a mere ~10mg of friction/stiction in both planes. The static downforce calibration was good to +5%, which is better than the arms fitted to many decks today. PM

Turntable speed error at 33.33rpm: 33.31rpm (–0.07%)
Time to audible stabilisation: 1-2sec
Peak Wow/Flutter: 0.02% / 0.04%
Rumble (silent groove, DIN B wtd): –66.1dB
Rumble (through bearing, DIN B wtd): –67.1dB
Hum & Noise (unwtd, rel. to 5cm/sec): –51.3dB
Power Consumption: 4W
Dimensions (WHD) / Weight: 430x106x375mm / 6.5kg