TechDAS Air Force III Premium Turntable Lab Report

Lab Report

While the original Air Force III [HFN Sep '16] shares a similar motor unit, air-suspended bearing and LP vacuum hold-down as the Air Force One [HFN Jun '13] and Air Force Two [HFN May '15], this 'Premium' version is substantially revised. Aside from the piano black/gold colour option (silver is also available) the deeper 29kg gunmetal platter is the most obvious giveaway, increasing its moment of inertia while – thanks to the increased torque of the AC synchronous motor – actually reducing start-up time from around 12 seconds to 8 seconds. Once again the pumped air escapes smoothly across the polished glass surface under the platter, raising the rotating mass by some 30μm and maintaining the through-bearing rumble at a very low –74dB (DIN-B wtd re. 1kHz at 5cm/sec). The superiority of this Premium model is particularly evident in the improved through-groove rumble, reduced here from –68.6dB (AF III) to –70.8dB with the vacuum hold-down in effect. Furthermore, the bearing mode noted at 36Hz in the AF III is shifted to 40Hz here [see Graph 2, below], and also reduced by 5-6dB in amplitude.

Excellent absolute speed accuracy remains a feature of the TechDAS decks – though precise tensioning of that inflexible polyurethane fibre belt is critical here – with the AF III Premium incurring a mere +0.012% offset at 33.33pm. Wow, already close to the limits of both engineering and measurement, remains unchanged at 0.02% (peak wtd) and is illustrated by the sharpness of the 3150Hz peak [see Graph 1]. Flutter is slightly reduced over the AF III from 0.04% to 0.03% in this Premium model and remains distributed as an innocuous 'white noise' on the spectrum. The discrete sidebands noted at ±15-20Hz with the AF III are also largely banished in the Premium. PM


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


Unweighted bearing rumble from DC-200Hz (black infill) versus silent LP groove (with vacuum pull down, blue; without, red) re. 1kHz at 5cm/sec

Turntable speed error at 33.33rpm 33.33rpm (+0.012%)
Time to audible stabilisation 8 seconds
Peak Wow/Flutter 0.02% / 0.03%
Rumble (silent groove, DIN B wtd) –68.5dB (–70.8dB with hold-down)
Rumble (through bearing, DIN B wtd) –74.0dB
Hum & Noise (unwtd, rel. to 5cm/sec) –53.1dB
Power Consumption 30-40W (20W idle)
Dimensions (WHD) / Weight 473x170x363mm / 55kg
Price £28,998
Stella Inc.
Tokyo, Japan
Supplied by: Absolute Sounds Ltd
0208 971 3909