Integrated Amplifiers

If you want to trace the genesis of the M8xi then look no further than Musical Fidelity's Titan power amp [HFN May '10], pictured here. This bridged power amp delivered 1050W/8ohm and 1996W/4ohm with a dynamic output of 5900W/1ohm (76.8A). Sure enough, the M8xi's dynamic delivery of 880W, 1740W and 1300W into 8, 4 and 2ohm is lower, and its 26.8A current capacity deliberately limited, but key features of the design are carried over. While the M8xi's output stage uses a newer version of Sanken's STD03N/03P Darlington power transistors (with built-in compensation diodes) it shares an idea from the Titan: each transistor is powered via its own dedicated 4700µF/80V reservoir capacitor. With three pairs of transistors per side of the bridge, or six pairs in total per channel, this gives 12 reservoir caps per channel, and these black/grey cans are clearly visible in our lid-off shot.

The preamp and digital circuits owe more to MF's Encore 225 streaming amplifier [HFN Dec '16] though the M8xi's USB input is a superior XMOS-based implementation. The 'Encore' line preamp has an improved layout in the M8xi and now has both balanced inputs and outputs even though, in practice, the preamplifier is single-ended in design. And that huge volume knob does not drive an analogue potentiometer – it's a rotary encoder (with no hysteresis, I might add, so spinning it quickly does not speed the volume change up or down) linked to a digital-governed volume control from Texas Instruments. PM