MoFi UltraDeck+M Turntable Package Lab Report

Lab Report

MoFi's flagship turntable is elegant in its simplicity but also ruggedly constructed. The bronze-sleeved bearing features a sapphire thrust pad and runs on an inverted steel spindle, although this is arguably 'overkill' to support the 3.1kg Delrin platter! Longevity is all but assured and while the –68.0dB through-bearing rumble (DIN-B wtd, re. 5cm/sec) is about average for a deck at this price, the through-groove rumble was more impressive at –71.4dB. In practice, the latter figure is really what matters. The torque generated by the 300rpm AC synchronous motor is partially lost by belt slippage on start-up, but the 4sec 'boot time' is more than swift enough. Absolute speed was all but bang on, with an error of just +0.05%, and very little low-rate drift, but wow was just a little higher than anticipated at 0.07% (peak wtd). Sidebands at ±5Hz are visible [see Graph 1, below] but higher-rate flutter is lower at 0.04% and essentially uncorrelated (noise-like).

Despite only accommodating cartridges up to ~10g in bodyweight [the supplied MasterTracker MM weighs 9.7g], MoFi's 10in alloy tonearm is a real heavyweight with an effective mass a little over 30g. This high mass not only best suits lower compliance pick-ups but it also explains the Q and definition of the bold resonances seen on the CSD waterfall plot [Graph 2, below]. The main bending mode is clear at 145Hz as are the harmonic/torsional modes at 440Hz, 710Hz and 980Hz. Some additional damping would certainly benefit the arm's performance although its elegant gimbal/ballrace bearings are beyond reproach at the price – absolutely free of any play while offering a very low <10mg friction. 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 33.34rpm (+0.05%)
Time to audible stabilisation 4sec
Peak Wow/Flutter 0.07% / 0.04%
Rumble (silent groove, DIN B wtd) –71.4dB
Rumble (through bearing, DIN B wtd) –68.0dB
Hum & Noise (unwtd, rel. to 5cm/sec) –59.7dB
Power Consumption 5W (<1W idle)
Dimensions (WHD) / Weight 500x152x362mm / 10.5kg
Price (with arm/cartridge) £2499
MoFi Electronics
Chicago, USA
Supplied by: Karma-AV Ltd, York
01423 358846