Accuphase A-45 Stereo Power Amplifier HiFi Engine AC100V From Japan

A pure Class A stereo power amplifier developed following design technology as an amplifier positioned between A-60 and A-30.

The entire amplifier configuration uses the latest instrumentation amplifier method.

This method uses a fully balanced signal path from the input terminal to the power amplifier stage, and not only has excellent characteristics such as CMRR (Common Mode Rejection Ratio) and distortion rate, but also It is resistant to changes in the surrounding environment such as noise, and has improved stability and reliability as a power amplifier.

The amplifier section is equipped with an MCS+ circuit and a current feedback amplifier circuit to further improve electrical performance.

MCS (Multiple Circuit Summing-up) is a circuit system that improves various characteristics by connecting identical circuits in parallel. The MCS+ circuit is a further evolution of this circuit, achieving even lower noise by extending the part that operates in parallel to the class A drive stage of the current-voltage converter.

The current feedback amplifier circuit is a method that feeds back the output signal in the form of a current, and since the impedance of the feedback input part is extremely low, phase rotation is less likely to occur and various characteristics can be significantly improved with a small amount of NFB.

A power MOS-FET, which has a reputation for sound quality and reliability, is used as the output element, and each channel is driven in 6 parallel push-pull formats. MOS-FET has negative characteristics against temperature rise, so it is possible to obtain thermally stable operation. This is a pure Class A method that brings out the charm of music.

A large-sized high-efficiency toroidal transformer with a maximum capacity of 600VA is used in the power supply section, and a large-capacity capacitor of 47,000μFx2 is used as the smoothing capacitor.

Equipped with 4-stage gain control.

This function switches the gain in the first stage amplifier section of the instrumentation amplifier system, which also reduces residual noise.

A fully balanced input circuit is adopted, making it less susceptible to external induced noise.

The copper foil surface of the printed board and the main parts of the signal path are made of gold plate.

Equipped with a large analog power meter.

Meter OFF function and sensitivity switching are also available.

  The speaker terminals are large terminals that can use Y lugs or banana plugs.

The A-45 supports bridge connections and can also be used as a high-power monaural power amplifier.

Use the mode switch to switch between dual mono/stereo/bridge connection.

Model stereo power amplifier

Rated continuous average output (20Hz to 20kHz) Stereo specification (both channels operating)

　360W+360W (1Ω load, limited to music signal)

　180W+180W(2Ω load)

　90W+90W(4Ω load)

　45W+45W(8Ω load)

When using monaural specifications (bridge connection)

720W (2Ω load, music signal only)

360W (4Ω load)

180W (8Ω load)

Total harmonic distortion rate Stereo specification (both channels operating)

0.05% (2Ω load)

0.03% (4Ω to 16Ω load)

When using monaural specifications (bridge connection)

0.05% (4Ω to 16Ω load)

IM distortion rate 0.004%

Frequency characteristics 20Hz to 20kHz +0 -0.2dB (at rated continuous average output)

0.5Hz to 160kHz +0 -3.0dB (at 1W output)

Gain 28.0dB (Gain switch: max)

Both stereo/monaural specifications

Gain switching Max, -3dB, -6dB, -12dB

Load impedance Stereo specification: 2Ω to 16Ω

Monaural specification: 4Ω to 16Ω

*For music signals only, stereo 1Ω and monaural 2Ω loads are possible.

Damping factor 200

Input sensitivity (8Ω load, Gain switch: max) Stereo specification

0.76V (at rated continuous average output)

When using monaural specifications

1.51V (at rated continuous average output)

0.11V (at 1W output)

Input impedance balance: 40kΩ

Unbalance: 20kΩ

S/N (A correction, input short) 115dB (Gain switch Max)

120dB (Gain switch -12dB)

At rated continuous average output

Output meter -50dB~;3dB (dB/% display)

Logarithmic compression type, display off function, meter sensitivity switching function (-20dB)

Power supply AC100V, 50Hz/60Hz

Power consumption 235W (no input)

430W (Electrical Appliance and Material Safety Law)

290W (at 8Ω load rated output)　

Accessories: Instruction manual (copy), power cable (non-genuine). No original box.

Maximum external dimensions Width 465x Height 211x Depth 464mm

Weight 30.9kg