Vintage

Dual provides a strobe pattern to assist in the manual fine-tuning of the CS 601's speed and, with the strobe 'stripes' stationary, its absolute accuracy was a mere –0.06% adrift. The belt-driven, flywheel-assisted mechanism – in practice a 1.3kg alloy platter with 0.8kg sub-platter and robust 8-pole synchronous motor – delivers good low-rate speed stability and a peak wow of just 0.03% [see Graph 1, below]. Higher-rate flutter components are a little more obvious with sidebands at ±10Hz, ±30Hz, ±43Hz and ±100Hz amounting to a peak-wtd figure of 0.08%. The latter is linked to the inbuilt PSU but the former three modes are also just visible on the unwtd rumble spectrum [not shown here]. The main bearing still met Dual's original >63dB weighted rumble specification at –64.5dB (DIN-B wtd, re. 1kHz/5cm/sec), a figure that improved to –65.7dB through-the-groove thanks, in all likelihood, to the rubber mat.

The 'torsion-resistant' 222mm effective length aluminium tonearm includes provision for a plastic 'cartridge holder' – headshell – with short fingerlift, and while this keeps the effective mass down to the sub-10g required for Shure's classic high compliance V15 III pick-up it also adds to the complexity of the arm's resonances [see Graph 2, below]. The main beam and headshell appear to bend at a low ~55Hz and ~85Hz [off the left hand X axis of Graph 2] with a series of other bending, twisting and harmonic modes associated with this, the 'self-adjusting' pivot bearing and other appendages at 185Hz, 260Hz, 290Hz, 400Hz and 560Hz. The spring-loaded downforce mechanism is effective but under-reads by up 20% at low settings (so a setting of 1g amounts to a 1.2g downforce and 2g is 2.15g). PM