Pre/Power Amplifiers

From switch-on followed by a one-hour ‘burn-in’, the M1.1’s temperature indication increased from 26oC to 51oC – this is the temperature of the output devices on the heatsink – while the output distortion was maintained at an unchanging 0.00045% (all re. 1kHz/10W/8ohm). This was with ‘global feedback’ set to the maximum 100% [see boxout] where distortion gently increases from 0.0004% to 0.0028% from 1W to the rated 200W/8ohm at 1kHz and 0.004% to 0.07% from 1-100W at 20kHz [see Graph 2]. In practice, the M1.1 comfortably exceeds its 200W spec., delivering 2x275W/8ohm and 2x505W/4ohm with enough in the tank to support 301W, 595W, 1.14kW and 2.03kW (45A) into 8, 4, 2 and 1ohm loads, respectively, under dynamic conditions [see Graph 1]. Note that the M1.1’s power display over-estimates by a factor of x4 (so 10W reads as 41W and 100W as 410W) but is fairly accurate when reporting on these dynamic, music-like, signals (<1% THD at 1kHz/10msec).

Either way, this sophisticated power amplifier is very tolerant of low impedance or ‘difficult’ loudspeaker loads while its low 0.012-0.035ohm output impedance holds the response to +0.0/–0.14dB into 8ohm, +0.0/–0.18dB into 4ohm and +0.0/–0.25dB into 2ohm (all re. 20Hz-20kHz). Wideband, the response has –1dB limits at sub-1Hz and up to 80kHz into 8ohm. In the default ‘0.0dB’ setting, overall gain is +23.75dB, requiring 2.6V from a balanced (XLR) source to raise the rated 200W/8ohm. Meanwhile, in common with the L1 preamp, noise is also fabulously low and the A-wtd S/N ratio very wide at 92dB (re. 0dBW). Finally, stereo separation is good to 100dB through the midrange and 80dB at 20kHz. PM