Dual CS 606 turntable Lab Report

Lab Report

Our reviewer had tweaked the Dual CS 606's pitch control in readiness for my lab tests and, simply by viewing the peripheral strobe pattern, had got the speed almost bang-on at 33.32rpm (–0.04%). Dual's EDS 500 direct-drive motor gets the 1.4kg platter up to speed within 3secs and although low-rate drift is almost entirely absent there is some discrete wow at ±2.6Hz together with a skirt of noise-like wow & flutter clearly visible either side of the test signal [see Graph 1, below]. The strong ±67Hz sidebands contribute to the overall 0.07% peak-wtd flutter – this frequency also appearing as a very sharp, well-defined peak (–52dB re. 1kHz/5cm/sec) on the through-spindle rumble spectrum. And here's the culprit: Dual's servo adjusts the platter's absolute speed 120x per revolution which, with a rotational frequency of 0.55Hz at 33.33rpm, equals the 67Hz pulse we see here... This does impact on the deck's through-groove rumble which is a below average –65.0dB (DIN-B wtd), though better than the through-spindle figure of –63.7dB.

The accuracy of the ULM arm's spring-loaded tracking force dial is superb with errors of just 1% over a full 0.5-2.0g range, unaffected by some residual play in the four-point gimbal bearing. The effective mass of the arm is around 6g and while the counterweight includes Dual's 'tunable anti-resonance' mechanism, it is really only suited to lightweight, high compliance MMs. The cumulative spectral decay of the lightweight alloy armtube [Graph 2, below] highlights a harmonic at 395Hz with the primary bending mode closer to a low 95Hz. Modes at 300Hz, 470Hz and 580Hz are well damped, 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)


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 (–0.04%)
Time to audible stabilisation 3sec
Peak Wow/Flutter 0.07% / 0.07%
Rumble (silent groove, DIN B wtd) –65.0dB
Rumble (through bearing, DIN B wtd) –63.7dB
Hum & Noise (unwtd, rel. to 5cm/sec) –52.0dB
Power Consumption 3W
Dimensions (WHD) / Weight 425x145x370mm / 6.5kg