Accuphase M-2000

Commentary

Monaural power amplifier developed for ideal constant-voltage drive.

A high power transistor with collector loss of 130W and collector current of 15A is used. This transistor is composed of 22-parallel push-pull for ultra-low impedance. These elements are mounted on a huge heat sink made of aluminum die-cast for efficient heat radiation processing.
As a result of this margin, we have realized a high output power amplifier that is linear up to ultra-low impedance loads, and also demonstrates excellent power in load drive performance including reactance components.

It uses a current feedback amplifier circuit that feeds back the output signal in the form of current.
First, the impedance of the input terminal on the feedback side is lowered to detect a current. The current is converted to I-V (current-voltage) by a transimpedance amplifier to produce an output signal.
Since the impedance of the feedback input part is very low, phase rotation is difficult to occur, and as a result, phase compensation is hardly required.
As a result, various characteristics can be greatly improved with a small amount of NFB, and excellent dynamic characteristics such as start-up and natural energy response can be obtained in terms of sound quality.

The bridge connection using two M-2000 s increases the output by a factor of four.
For bridge connection, input signals of the same voltage and opposite phase to each other to two amplifiers, and connect speakers to the output terminals of both amplifiers.
When connected to a bridge, the amplifier can obtain four times the output power and is a 1000W/8 Ω ultra-class monaural amplifier.

Equipped with balanced connection terminal that is less susceptible to external induction noise.

High-purity copper is usually used for components through which signals pass. The M-2000 is plated with gold on this copper.
The printed board's copper foil surface, the earth plate through which a large ripple current flows, the capacitor terminal, the input terminal, and the speaker terminal are all designed to improve sound quality.

The power supply section uses a large super-ring toroidal transformer with a large power capacity of approximately 1.5 kva.
This transformer is fixed to a non-resonant aluminum case with a high-efficiency heat radiation structure using a filler material with excellent heat conduction and high vibration damping effect to block external influence.
In addition, the cross-section of the iron core is close to a circle and the coil can be wound close to a circle. Since adhesion is good, loss and weight are reduced. Leakage flux during loading is small, and groaning and vibration are also small. In addition, iron loss and inrush current are reduced by reducing the cross-section of the iron core and increasing the weight ratio of the copper wire.
Two large electrolytic capacitors of 40000 μ F / 120 f / WV are used.

It is equipped with a phase switch that inverts the phase of the whole equipment.
There is no degradation of sound quality because the switching method is only to exchange the plus and minus of the balance amplifier input.

Equipped with a large power meter of logarithmic compression type.
Meter operation and lighting can be ON/OFF.

Equipped with a very large speaker terminal that can be used with very thick speaker cables.
The material is a gold plate made by cutting out solid brass, and a mold cap for insulation is put on it.

Model Rating

Type	Monaural power amplifier
Rated continuous average power (between 20 Hz to 20 kHz)	1 Ω load : 2000W (music signal only) 2 Ω load : 1000W 4 Ω load : 500W 8 Ω load : 250W
Total harmonic distortion factor	1 ohm load : 0.1% 2 Ω load : 0.05% 4 Ω ~ 16 Ω load : 0.03%
IM distortion factor	0.003%
Frequency characteristic	Rated continuous average output : 20 Hz ~ 20000 Hz + 0 -0.2 dB At 1W output : 0.5 Hz ~ 160000 Hz + 0 -3.0 dB
Gain	28.0dB
Load impedance	Continuous output : 2 Ω ~ 16 Ω Music signal : 1 Ω ~ 16 Ω
Damping factor	400
Input sensitivity (8 Ω load)	Rated continuous average output : 1.78 V 0.11 V at 1W output
Input impedance	Balance : 40k Ω Unbalanced : 20k Ω
S/N (A-corrected)	120 dB (at input short circuit, rated continuous average output)
Output meter	Logarithmic compression type -60dB to + 3 dB and output direct reading scale
Pwer	100 VAC, 50Hz/60Hz
Power consumption	No input : 180W Electrical Appliance and Material Control Law : 950W 8 Ω rated output : 585W
External dimensions	Width 475x Height 252x Depth 545 mm
Weight	50kg