Vintage

Based on the classic Hitachi MOSFET power amp application circuit, driven here by two cascaded differential stages running in Class A, Myst's TMA3 meets its 2x35/8ohm specification by delivering 2x40W/8ohm and 2x55W/4ohm. Each channel has a pair of 2SJ82/2SK226 Hitachi MOSFETs that are mounted on limited heatsinking – the external fins exceeding 55°C at continuous power levels over 5W/8ohm, so good ventilation is mandatory. Protection is afforded by a 2.5A anti-surge fuse in line with each channel's output but the TMA3's dynamic power output still stretches to 47W, 77W, 101W and 103W into 8, 4, 2 and 1ohm loads, respectively, or ~10A for a period of 10msec at <1% THD [see Graph 1].

Myst offers two levels of gain via either the tuner/tape/aux input and via the dedicated CD input, the latter bypassing the active preamp stage to offer an overall gain of +29.6dB. One effect is to optimise the performance of the ALPs volume control which, even in our 30+ year-old sample, offered a channel balance within 0.1dB over the top 40dB of its dynamic range. Noise, too, is still in tune with many contemporary amplifiers, yielding an A-wtd S/N ratio of 84dB (re. 0dBW). Distortion, however, brings some 'colour' to the TMA3 for while it remains fairly consistent with power output (0.04-0.06% from 1-35W at 1kHz), it does increase quite smartly with increasing frequency. The minimum of 0.005%/20Hz rises to 0.05%/1kHz and then up to 0.5%/20kHz and 1.2%/40kHz [see Graph 2]. The response also shows a low bass roll-off of –1.3dB/20Hz but with a slight rise at very high/ultrasonic frequencies of +0.2dB/20kHz – a trend that's exaggerated into lower impedance loads. PM

Power output (<1% THD, 8/4ohm): 40W / 55W
Dynamic power (<1% THD, 8/4/2/1ohm): 47W / 77W / 101W / 103W
Output imp. (20Hz–20kHz/100kHz): 0.073–0.115ohm / 0.56ohm
Freq. resp. (20Hz–20kHz/100kHz, 0dBW): –1.3dB to +0.15dB / –1.1dB
Input sensitivity (for 0dBW/35W): 93mV / 560mV
A-wtd S/N ratio (re. 0dBW/35W): 84.2dB / 99.6dB
Distortion (20Hz-20kHz, 10W/8ohm): 0.005–0.48%
Power consumption (Idle/rated output): 14W / 128W
Dimensions (WHD) / Weight: 432x55x220mm / 4.5kg