This YAMAHA pre-power amplifier combo was part of the Limited Centennial Edition #10000 Series introduced in 1987. The Limited Centennial Edition line of stereo components included the MX-10000 Amplifier, the CX-10000 Control Amplifier, the CDX-10000 Compact Disc Player, the HX-10000 Phono Equalizer Amplifier, the NSX-10000 Speakers. The MX-10000 is Yamaha's finest ever pure Class A operation amplifier, with sound quality characteristics approaching perfection. This is the ultimate Class A, surpassing all performance limitations. The one serious drawback to Class A operation has been finally eliminated, thanks to Yamaha's HC Class A circuit. The HC Class A circuit is elegantly simple, consisting of just two dual transistor circuits. The HC Class A circuit converts input current perfectly into positive and negative hyperbolic characteristics at a high speed. To put it briefly, the MX-10000 constantly delivers pure Class A operation without switching and without cut-off for all power domains and into all loads. Class A operation is assured in large current output operation with a superior dynamic power range.
Rated output is at 300W x 2 into 6 ohms, and dynamic power is an awesome 1,200W x2 into 1 ohm. Eight high-power MOS FETs (four pairs of Toshiba 2SJ123 and 2SK442) are used in each channel in a quadruple push-pull arrangement in the output power stage to provide the HC circuit with low-load Class A operation. Developed exclusively for the MX-10000, these MOS FETs permit large-current high-speed operation. The power MOS FETs are controlled by multiple carrier control, resulting in excellent wide-range amplification characteristics, with none of the problems caused by switching distortion. Although the awesome figure of 1,200 watts per channel of dynamic power into 1 ohm is impressive, the resulting music's overwhelmingly grand, yet smooth quality is even more so. In addition to the HC Class A circuit, there is a pre-drive voltage amp which amplifies the voltage of the very weak input signals that are directly connected to the input terminals and provides Class A operation the same as in the output stage. This means a high through-rate of 500 V/µsec at this stage and a gain of 30 dB, reducing negative effects due to noise. Moreover, with low impedance, the antinoise characteristics are improved remarkably.
The result is exceedingly pure high-power amplification, featuring 0.0005% distortion and an S/N ratio of 132 dB. The MX-10000 incorporates power buffer amplifiers which supply the power required for the Class A output stages with power MOS FETs. This Class A configuration using Yamaha original dual amplifiers solves the heat-radiation problems that can occur during Class A operation. To supply a large power output promptly to the output stage, the power buffer amplifiers use high ft power transistors with superb audio characteristics in a sextuple push-pull configuration, six for N CH and six for P CH, i.e. 12 in each channel (Sanken's 2SA1216 and 2SC2922). Since this dual-amplifier Class A configuration adopts non-current grounding which is used only for determining the ground potential, amplifier operation instability due to current flow into the ground is eliminated. The MX-10000 is constructed of highly-rigid, non-magnetic material. The front panel of extruded aluminum is half an inch thick. Even the weight and design of the screws have been carefully analyzed, in order to ensure that rigidity is uniformly applied throughout.
The partnering CX-10000 is not a pre-amp in the conventional sense. Nor is it a conventional analog pre-amp in any sense. Instead, the CX-10000 is a tru control amplifier because it offers vastly more control over the final sounds you hear than was possible with any of its predecessors. And it is a true digital control amplifier here Digital input is received directly without analog conversion. Signal is digitally processed with the help of Digital Parametric Equalization and Digital Sound Field Processing.