YAMAHA MX-2000

Commentary

This stereo power amplifier was developed as a reference for the AV multimedia era.

Equipped with Yamaha's original HCA (Hyperbolic Transformation and Amplification) circuit, it realizes A-feeding operation for full load and full power range.
The HCA circuit incorporates a conversion circuit of a current mirror circuit configuration with two dual transistors in the driver stage at the front stage of the power buffer, and realizes the input / output linearity of A supply operation regardless of the load level or power value.
Also, the HCA circuit has no feedback loop or gain and acts as a pure converter, so it has a good transient response.

Power MOS FET is used for the output terminal of the power buffer stage.
The power MOS FET is a voltage control element with high input impedance, and has features such as reducing the load on the driver stage and simplifying the circuit.
A class A rated output of 150W + 150W has been achieved in a 4-para push-pull configuration using eight power MOS FETs per channel.

The first stage voltage amplifier for voltage amplification employs a dual FET differential input cascode bootstrap circuit. The combination of a high-gain dual FET with low current leakage and a wide-band transistor realizes wide-band characteristics and a high-slew rate resistant to transient input.
In addition, the voltage amplifier board is set close to the input terminal to achieve low noise and high S/N.

To ensure perfect matching with the speaker system and stable drive performance, only one speaker output is provided.
Since there is only one system, distortion of the overall from the input to the output is completely eliminated by installing a unique direct error collection amplifier.
This new amplifier directly inverts and inputs the distortion to the voltage amplifier from the hot / grounded terminals of the speaker output terminal. It eliminates the slight distortion of the output element and the nonlinear components of the speaker relay and output coil. In addition, it cancels the potential difference between the input terminal and the output terminal ground caused by the DC resistance of the wiring material, and improves various characteristics.

A new low-resonance chimney type heat sinker has been adopted, and the heat radiation part has an oval shape with no acute angle, thereby eliminating the heat sinker noise caused by resonance.
The heat sinker the heat itself is molded integrally with the aluminum extruding, which greatly improves the structural strength.
We are also working to reduce the impedance of power and output lines by embedding gold-plated bus bars in the power stage substrate.
In addition, Chemi-Con for audio has been fully adopted.

The power supply section is designed to meet the requirements and noise requirements of the power supply. It uses a 420 VA large massive transformer with an EI core and a 20,000 μ Fx2 low-power aluminum electrolytic capacitor. In particular, the aluminum electrolytic capacitor for smoothing is a large one with a diameter of 76 mm. By using low-power aluminum electrode foils and improving the electrolyte solution, ionic impurities are reduced.

In order to minimize crosstalk and maximize the separation between the left and right channels, consideration is given not only to the independence of the signal circuit but also to the internal construction such as the path from the input terminal to the speaker output terminal and the arrangement of the power block.
The MX-2000 uses symmetrical construction on the left and right sides. The power transformer and Chemicon for smoothing are placed in the center of the chassis. Each LR power block is placed on the left and right sides to improve the separation. In addition, the good weight balance stabilizes the legs.
In addition, the voltage amplifier circuit board for handling weak signals, the speaker relay and the output coil through which high current signals pass are separated into upper and lower parts using 2 box construction. By placing the voltage amplifier circuit board on the upper side and the speaker relay and the output coil on the lower side, interference of input and output signals is eliminated.
In addition, high rigidity aluminum extruding material is used for the front panel and top cover, and all the inner chassis and frame are non-magnetic and copper-plated to reduce the influence of magnetic strain.

Equipped with LR independent high-speed peak level meter of dB scale logarithmic compression type.

It uses a protection linked speaker switch that can turn on / off the speaker output while the power is on standby, an LR independent tent-type input attenuator, a brass gold-plated pin jack terminal, a brass gold-plated speaker terminal that supports extremely thick cable, and an OFC power cord with polarity display.

Model Rating

Type	Power amplifier
Rated Output (20 Hz ~ 20 kHz)	180W + 180W (4 Ω, Strain 0.01%) 150W + 150W (6 Ω, 0.003% strain) 130W + 130W (8 Ω, 0.003% strain)
Power bandwidth	10 Hz to 100 kHz (8 Ω, 65W, 0.02% distortion)
Damping factor	1000 or More (1 kHz, 8 Ω)
Input Sensitivity / Impedance	1.2V/20k Ω
Frequency characteristic	20 Hz ~ 20 kHz + 0 -0.3 dB
Total harmonic distortion factor	0.003% (8 Ω, 20 Hz-20 kHz, 130W)
Signal-to-noise ratio	125 dB (IHF-A input short)
Residual noise	15 μ V (IHF-A)
Channel separation	95 dB (1 kHz, Input Short)
Power supply voltage	100 VAC, 50Hz/60Hz
Power consumption	350W
External dimensions	Width 473x Height 170x Depth 469 mm
Weight	28kg