Dual CS 600 Turntable Lab Report

Lab Report

The licence holders of the Dual brand, Alfred Fehrenbacher GmbH, have specified a brass bearing with a Teflon thrust pad for this CS 600 model. While this is not the quietest bearing we've ever tested – the DIN-B wtd rumble is –64.5dB (re. 1kHz/5cm/sec) – the thick felt mat provides sufficient insulation that the through-groove rumble is a very impressive –71.4dB. So far, so good. The 1.05kg alloy platter is damped by a peripheral rubber insert, and seems fairly inert, while the DC motor drives a lightweight plastic sub-platter and brings the deck up to speed within 4secs. There is some slight drift (sub-1Hz wow), seen on the W&F spectrum as a broadening of the main peak, although the peak-wtd figures are acceptable at 0.05% and 0.04%, respectively [see Graph 1, below]. The clusters of peaks within ±20Hz on the W&F spectrum are also visible on the rumble plots.


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

The partnering 8.5in alloy tonearm offers a low 7-8g effective mass that will suit moderate-to-high compliance MM pick-ups. The 'quadruple' cardan-type bearing looks substantial enough but while any residual play was minimal, lateral friction was a little higher than expected at 50mg in our sample (vertical was closer to 20mg). The straight but lightweight alloy tube has a predictably low frequency main bending mode at 90Hz with a cluster of harmonic and torsional modes at 280Hz, 370Hz, 430Hz, 580Hz and 660Hz [see Graph 2, above]. There are a smattering of short-lived modes at higher frequency but it's the substantial 100g mass of the counterweight that's of arguably greater concern. Coupled with this lightweight arm/carbon fibre headshell, your choice of pick-up will need to weigh >8g to both balance the arm and achieve a useable 2g tracking force. PM

Turntable speed error at 33.33rpm 33.37rpm (+0.096%)
Time to audible stabilisation 4sec
Peak Wow/Flutter 0.05% / 0.04%
Rumble (silent groove, DIN B wtd) –71.4dB
Rumble (through bearing, DIN B wtd) –64.5dB
Hum & Noise (unwtd, rel. to 5cm/sec) –59.6dB
Power Consumption 3W (1W standby)
Dimensions (WHD) / Weight 440x135x370mm / 8.3kg
Price £1399
Alfred Fehrenbacher GmbH
St. Georgen, Germany
Decent Audio Ltd, UK
05602 054669