Yamaha MX10000 & KEF 104/2 скачать в хорошем качестве

Yamaha MX10000 & KEF 104/2

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. Previously, when a load current greater than double that of the idling current was produced, the amplifier would begin non-linear class AB operation. This in turn caused a slight deterioration in the remarkably fine sound quality characteristics exhibited by pure Class A operation. But no longer. Since the HC Class A circuit does not include discontinuous points, as do conventional amplifiers, it is capable of performing Class A operation while maintaining input-output linearity as long as the capacities of input/output stage devices and power supply allow. The HC Class A circuit is elegantly simple, consisting of just two dual transistor circuits. There are no internal envelope circuits, which could vary the characteristic curves in a complicated way, or feedback circuits, which delay the transmission characteristics. 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. This means for load currents from zero to infinity. At any operation point, the HC Class A circuit provides a linear composite characteristic of N CH and P CH at the final stage. Together with the positive and negative hyperbolic characteristics, Class A operation is thus 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. To prevent signal degradation, only a single pair of stereo outputs are provided as the speaker output system. Any distortion that occurs before reaching the speaker terminals is cancelled by the Direct Error Correction Amplifiers, which can detect even very small deviations in linearity that can occur in the speaker protection relays and output coils as well as in the output stages. The MX-10000 amplifier achieves the ultimate in ultra low distortion operation. 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. In addition, computer analysis has been used to ensure linkable strength between the various construction materials as well as for the reduction of vibration dispersion. For example, the thickness of the cooling fin base, fin length and form, have been combined to yield a one-piece heat sink reflecting a gradation structure which vastly reduces unwanted oscillation.