Commentary　

This is a pure class A stereo power amplifier designed based on M-2000 design technology.
The impedance of the amplifier output is low and the speaker is driven at constant voltage.

The output amplifier stage employs a power MOS FET having a negative thermal operation characteristic. By driving the FET in parallel push-pull operation with 10 pairs per channel, stable linear power is obtained up to ultra-low impedance load, and MOS The allowable loss power of one FET is 120W, but the power load per pair is 5W. The low power region with excellent linearity of the FET can be used efficiently.
A power MOS FET is also used in the drive stage. By connecting the power MOS FET with a cascode, the frequency characteristics are broadened and the negative feedback is reduced, contributing to improved sound quality.
With this circuit configuration, the output voltage remains almost constant even when the load changes, and the clipping power is designed to be sufficient with measured values of 513W for 1 Ω, 343W for 2 Ω, 202W for 4 Ω, and 110W for 8 Ω.

It uses a current feedback amplifier circuit that feeds back the output signal in the form of a current.
The principle of this circuit is that a current is detected by reducing the impedance of the input terminal on the feedback side, and the current is converted into I-V (current-voltage) by a trans-impedance amplifier to produce an output signal.
In this circuit, since the impedance of the feedback input part is very low, phase rotation hardly occurs and phase compensation is hardly necessary, so various characteristics can be greatly improved with a small amount of NFB.

The A-50V is equipped with a switch for bridge connection and can be upgraded to a monaural power amplifier by bridge connection.

Equipped with balanced connection terminals.
In balanced transmission, the noise components generated in the cable are in phase with both poles, so when they are combined, only the noise components are canceled and good signal transmission is possible.

High-purity copper is used for components through which signals pass.
On the A-50V, gold plates are used for the copper foil surface of the printed board, earth plate for large ripple current, capacitor terminal, input terminal, and speaker terminal.

The speaker terminal is equipped with a very large speaker terminal that can be used with very thick speaker cables.
The material is machined out of solid brass into a gold plate, on which a mold cap is placed for insulation.

A large toroidal transformer with a large power capacity of approximately 1 kVA is used in the power supply section. In addition, it is fixed to a non-resonant aluminum case with a high-efficiency heat radiation structure by using a filler with a high vibration damping effect with excellent heat conduction, thereby reducing the external influence.
The toroidal transformer used in the A-50V uses a super-ring type. The cross-section of the iron core is close to a circle, and the coil is close to a circle so that it can be wound with good adhesion. This reduces loss and reduces waviness and vibration.
Furthermore, by reducing the cross-sectional area of the iron core and increasing the weight ratio of the copper wire, iron loss and inrush current are reduced.
Two aluminum electrolytic capacitors with 82,000 μ F capacity are installed.

Equipped with a digital power meter that is convenient for monitoring.
First, the current and voltage are detected then uses an analog multiplier to calculate the power value and displays it digitally.
The display stationary time (hold time) can be switched between 1 second and infinite (∞) time, and can be turned off when the display is not required.

Model Rating

型式	Stereo Power Amp
Rated continuous average power (between 20 Hz and 20 kHz)	Stereo (both channel operation) : 400W/ch (1 ohm) 200W/ch (2 Ω) 100W/ch (4 Ω) 50W/ch (8 Ω) Monaural (bridge connection) : 800W (2 ω) 400W (4 Ω) 200W (8 Ω)
Total Harmonic Distortion Factor	Stereo : 0.05% (2 Ω) 0.03% (4 Ω - 16 Ω) Monaural : 0.03% (4 Ω - 16 Ω)
IM Distortion Factor	0.003%
Frequency Response	20 Hz to 20 kHz + 0 -0.2 dB at rated continuous average output 0.5 Hz ~ 160 kHz + 0 -3.0 dB at 1W Output
Gain	28.0 dB (both stereo and monaural specifications)
Load Impedance	Stereo : 1 Ω ~ 16 Ω Monaural specification : 2 Ω ~ 16 Ω
Damping factor	100 (both stereo and monaural specifications)
Input sensitivity (8 Ω load)	Stereo : 0.80 V at rated continuous average power 0.11 v at 1W output Monaural : 1.59 V at rated continuous average power 0.11 v at 1W output
Input Impedance	Balance : 40k Ω Unbalanced : 20k Ω
S/N (A correction)	110 dB at input short circuit, rated continuous average output
Digital Output Meter	Type : True value display type of power View Range 0.1W ~ 400.0W (Stereo) 1W ~ 2000W (monaural specification) Hold Time : 1 second / ∞ Switching Type With Display / Off function
Power Supply	100 VAC, 50Hz/60Hz
Power Consumption	No input : 310W Electrical Appliance and Material Control Law : 550W 8 Ω rated output : 380W
External Dimensions	475 mm wide x 239 mm high x 545 mm deep
Weight	45.1kg