Philips GA 202 Electronic Turntable Lab Report

Lab Report

The pulley, belt and freewheel drive mechanism described by Tim in our review is clearly innovative but not without some technical compromise. Specifically, while the high-speed DC motor can be fine-tuned to deliver a very impressive –0.04% absolute speed accuracy, there is still some 'dynamic' drift as the adjustments of the servo are relayed through the pulleys and belts. Visible as a very low-rate wow [Graph 1], amounting to peak-wtd figure of 0.08%, this drift rarely impacts on the listening experience as obviously as might a higher-rate (2-10Hz) wow. Many listeners may well be oblivious... No special claims were made for the GA 202's main bearing and, indeed, the original '–60dB (DIN-B)' rumble specification is hardly extravagant. In fact, the GA 202 achieved a through-bearing figure of –66.5dB (DIN-B wtd) improving to a very creditable –70.5dB measured through the groove – testament to the isolation afforded by the platter and bonded hard-rubber mat.

The short, straight tonearm (effective length 222mm) with offset headshell, exhibits a main bending mode at a low 70Hz with a harmonic/twisting mode at 185Hz – these low frequency resonances being complicated by the sliding counterweight/ collar midway along the alloy tube. There are other, higher-Q, modes at 335Hz and 710Hz more likely associated with the headshell assembly [see Graph 2]. In terms of its utility, however, Philips' sliding collar is very accurately calibrated, each division representing +1.04g of additional downforce. Finally, the 9g effective mass of this delicate-looking arm is, perhaps, slightly higher than might be anticipated, but it is well suited to the ~18cu compliance of the partnering GP 500 MM pick-up. 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 (–0.038%)
Time to audible stabilisation 3-4sec
Peak Wow/Flutter 0.08% / 0.04%
Rumble (silent groove, DIN B wtd) –70.5dB
Rumble (through bearing, DIN B wtd) –66.5dB
Hum & Noise (unwtd, rel. to 5cm/sec) –49.7dB
Power Consumption 4-5W
Dimensions (WHD) / Weight 390x330x120mm / 7.5kg