Turntables, Arms & Cartridges

There are close parallels between this new PD-151 and the beefier PD-171 [HFN Dec '13] – the platter is fractionally lighter but the main bearing with its brass bushes, PEEK thrust pad and molybdenum oil is very similar. The thick rubber drive belt is shared too, but there's a key difference in the motor: the PD-171 uses an AC synchronous type while the PD-151 has a new, 'high torque' brushless DC design. It's not uncommon to see a sub-1Hz drift with decks that employ a DC motor solution, but Luxman has nailed the problem here, as evinced by the relative sharpness of the W&F spectrum [see Graph 1]. Peak wow is just 0.03% and the absolute speed +0.3% fast, before adjustment.

Measurement with a rumble coupler reveals some low frequency bearing noise not adequately reflected in the –69.5dB (DIN B-wtd) figure. Broad clusters of noise are visible in the unweighted spectrum, not shown here, at ~90Hz and ~160Hz but these are very effectively damped by Luxman's 'old school' heavy rubber mat that reduces through-groove rumble and noise to just –73.5dB – a superb figure up with the best turntables on offer. Meanwhile the resonant modes of the partnering S-shaped tonearm – inspired by Ortofon's TA-110 [HFN Mar '12] – are encouragingly quick to decay. A series of low-Q resonances at 65-110Hz are followed by higher-Q harmonic/torsional modes at 220Hz, 310Hz, 460Hz [see Graph 2]. Note that the 'dial up' counterweight is poorly calibrated, over-reading the expected value. Setting a desired '1g' results in a tracking force of just 0.6g; 2g gives just 1.1g and 2.5g yields 1.3g. An external tracking force gauge is therefore essential if you are to avoid running your pick-up too light in the groove. PM