Sony PS-FL7 turntable Lab Report

Lab Report

Combining a direct-drive platter with a linear-tracking arm in one compact package, this mid-'80s vinyl-spinner was clearly aiming to address both technical and practical (user convenience) issues in one stroke. The BSL (brushless/slotless) motor brings the diecast platter up to speed within 2 seconds with, for the era, a very respectable –68dB DIN-B wtd through bearing/motor rumble. Moreover, the integral rubber mat affords some further isolation so that through-groove rumble is lower still at –70.6dB. These are good results, as is the absolute speed accuracy of –0.02%, although there is some very low-rate drift evident in the W&F spectrum [see Graph 1, below]. Below the range of typical W&F measurements, this sort of drift is typically associated with poorly executed DC motor/belt-drive decks, not a quartz-locked direct-drive, and contributes significantly to the >0.3% peak-wtd W&F. This may also be linked to a very strong peak at 2.2Hz detected in all the rumble spectra [not shown here], equivalent to –63dB re. 1kHz/5cm/sec.

The 3.5in linear-tracking arm, its effective mass estimated at 4-5g, drops the stylus into the groove at a downforce of 1.4g, both figures appropriate for the high compliance XL-250G cartridge system that accompanied this deck. The arm fixing is inherently 'loose' so there is significant 'play' in both planes. Neither is there any significant damping – the cumulative spectral decay of the lightweight alloy box-section tube [Graph 2, below] highlighting a broad bending mode deferred to 160Hz with related resonances at 270Hz and 320Hz. The high-Q modes at 649Hz and 980Hz are short-lived, the arm's limited mass contributing to their quick decay. PM


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


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

Turntable speed error at 33.33rpm 33.33rpm (–0.02%)
Time to audible stabilisation 2sec
Peak Wow/Flutter 0.25% / 0.07%
Rumble (silent groove, DIN B wtd) –70.6dB
Rumble (through bearing, DIN B wtd) –68.0dB
Hum & Noise (unwtd, rel. to 5cm/sec) –62.8dB
Power Consumption 6W
Dimensions (WHD) / Weight 430x96x382mm / 7.5kg