Clearaudio Reference Jubilee Turntable Lab Report

Lab Report

While Clearaudio's 8.5kg, 15mm-thick stainless steel main platter and 50mm-thick POM top platter are belt-driven, the DC motor is governed by what Clearaudio describes as its OSC or 'Optical Speed Control'. The optical sensor can be seen near the inverted ceramic bearing in our 'platter off' shot, part of a hybrid digital/analogue drive synthesiser that evidently results in a very fine absolute speed accuracy of +0.03% and also a very low peak wtd wow of just 0.02% [see Graph 1, below]. Flutter is rather higher at 0.07% but is seemingly distributed in a semi-random, noise-like fashion – analogue but digitally 'dithered'! Interestingly, while there's little advantage in speed stability when upgrading to the 'Professional Power 24V' from the default 'wall wart', the reduction in rumble is little short of astonishing. Measured both through the groove and directly through the magnetically-assisted bearing, the DIN-B wtd rumble measured ~–64.8dB – rather below average – but this was lifted to an above-average –70.2dB (through-groove) with the PSU upgrade in place.

In the 12 years since we first tested Clearaudio's 9in Universal tonearm [HFN Nov '10], the outward appearance of its substantial (ball-race) bearing housing and three-part tapering-diameter carbon-fibre armtube looks unchanged. Within, however, Clearaudio has clearly improved the damping and resonance-control of the tube's main beam mode – seen here at 175Hz – and torsional/harmonic modes at 270Hz, 410Hz, 670Hz and 860Hz [see CSD waterfall, Graph 2]. In short, the latest Universal arm is markedly less 'lively' than the launch version. Bearing play is almost undetectable and friction/stiction below 10mg in both planes. PM

1122clear.lab1

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

1122clear.lab2

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

Turntable speed error at 33.33rpm 33.34rpm (+0.03%)
Time to audible stabilisation 3-4sec
Peak Wow/Flutter (Peak wtd) 0.02% / 0.07%
Rumble (silent groove, DIN B wtd) –70.2dB (with PP 2V upgrade)
Rumble (through bearing, DIN B wtd) –66.8dB
Hum & Noise (unwtd, rel. to 5cm/sec) –54.7dB
Power Consumption 5W (1W standby)
Dimensions (WHD) / Weight 495x160x343mm / 22kg
Prices £17,500 (inc. PP 24V PSU), £5000 (Universal arm)

COMPANY INFO
Clearaudio Electronic GmbH
Germany
Supplied by: Sound Fowndations, UK
0118 981 4238
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