Turntables, Arms & Cartridges

Refurbished it may well be, and by proven masters of precision engineering to boot, nevertheless the fact that a donor motor unit that's 60-70 years old can achieve a technical performance of this standard is quite astonishing. Sure enough, the magnet in the eddy current brake will naturally demagnetise over a half century which explains why the platter (the motor) was running about +0.25% fast with the speed adjust knob set mid-position. Turning it about a third way towards '-ve' brought it to a precise absolute speed and with levels of peak-wtd wow (0.03%) and flutter (0.04%) that would not disgrace a state-of-the-art deck from 2024 [see Graph 1, below]. The former figure is based on a ±2.2Hz component related to the 1:4 ratio of the inner platter and intermediate (idler) wheel diameters, but is still very low. More significant 'flat spots' on the periphery of the idler wheel would increase low-rate/wow speed variations.

There are also two sources of noise to contend with - not only rumble from the bearing but also from the coupling of the motor, via the high speed pulley and idler wheel, to the inside edge of the platter. The tool steel spindle is original but the new phosphor bronze sleeve, ball bearing and thrust pad seemingly contribute less to the -65.9dB through-bearing noise (DIN B-wtd)

than the shaded-pole induction motor [black spectrum, Graph 2]. The importance of the original ribbed rubber mat - again painstakingly reformulated here - in damping the platter modes is reflected in the far superior -70.9dB through-groove noise figure, this now on a par with the best contemporary decks [blue spectrum, Graph 2]. (The increase in sub-10Hz through-groove noise stems from the arm/cart resonance.) In short, the 301 Advanced is a fully-fledged resurrection! PM

Above: Wow And Flutter Re. 3150Hz Tone At 5Cm/Sec (Plotted ±150Hz, 5Hz Per Minor Division)

Above: Unweighted Bearing Rumble From Dc-200Hz (Black) Vs. Silent Lp Groove (Blue) Re. 1Khz At 5Cm/Sec