Technics SL-J33 turntable Lab Report

Lab Report

Comparisons with another recently-reviewed compact direct-drive deck, complete with integral linear-tracking arm, are instructive. I say 'recent' but Sony's SL-PF7 [HFN Mar '20] was also serving the market for highly automated vinyl-spinners alongside the Technics SL-J33 at a time when CD was really gaining traction among progressive audiophiles. Both turntables employed quartz-locked, brushless DC motors and brought their respective platters – both also relatively lightweight diecast alloy affairs – up to speed within 1-2 seconds. In each case the decks used an integral rubber mat that afforded some further isolation from direct motor/bearing noise, but Sony's SL-PF7 demonstrated a 1dB advantage over the Technics SL-J33 which registered –69.2dB (DIN-B wtd) for through-groove rumble. It was impossible to measure a through-bearing figure because power to the SL-J33's motor is cut once the integral lid is lifted...

Speed stability, on the other hand, was rather more the SL-J33's forte, this vintage deck boasting an absolute speed error of just –0.03% and with a peak wow and flutter of just 0.07% [see Graph 1, below]. The W&F spectrum shows some low rate wow, visible as a broadening of the main peak, along with a discrete set of flutter sidebands at ±15Hz. These contribute to the 0.04% peak flutter and are also visible on the unwtd. rumble spectrum [see Graph 2, below] as bearing noise, the latter at least partially boosted by the arm/cartridge resonance. The short (105mm) linear-tracking arm has a rated effective mass of 9g including the 6g plug-in MM cartridge. Some slight hum pick up is also revealed, but this is relatively low at –65dB (re. 1kHz/5cm/sec) and barely visible as a component of the W&F spectrum. PM


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


Unweighted rumble from DC-200Hz via silent LP groove re. 1kHz at 5cm/sec. Note correlation with peaks around 15Hz on W&F spectrum [Graph 1]

Turntable speed error at 33.33rpm 33.32rpm (–0.03%)
Time to audible stabilisation ~1-2sec
Peak Wow/Flutter 0.03% / 0.04%
Rumble (silent groove, DIN B wtd) –69.2dB
Rumble (through bearing, DIN B wtd) See text
Hum & Noise (unwtd, rel. to 5cm/sec) –65.1dB
Power Consumption 5W
Dimensions (WHD) / Weight 315x88x315mm / 4.1kg