ACCUPHASE A-20V

Second-hand. In excellent conditions. Free from visible signs of wear. Comes with original packaging and manual.

The ACCUPHASE A-20V is a pure Class-A stereo amplifier that employs power MOS-FET transistors, designed following Accuphase’s renowned design philosophy and circuit technologies such as constant voltage drive and low impedance. Its output stage uses three pairs of MOS-FETs in a parallel push-pull configuration per channel, ensuring stable and linear power delivery even under very low impedance loads. This parallel arrangement lowers the internal impedance and residual noise while effectively dissipating the heat generated, improving operational efficiency at low power ranges and delivering high-quality sound performance.

The A-20V limits maximum clipping to 50 watts into 8 ohms to protect against momentary music signal peaks, but actual measurements show much higher values: 156 watts at 1 ohm, 126 watts at 2 ohms, 85 watts at 4 ohms, and 50 watts at 8 ohms, providing a wide safety margin. It uses a current feedback amplifier circuit that detects the output signal as current and converts it into voltage via a transimpedance amplifier, minimizing phase rotation and the need for compensation, thus ensuring natural energy response and superior sonic transparency.

Thanks to the circuit’s stability, the A-20V allows gain control by adjusting the amount of negative feedback, simultaneously reducing residual noise—a feature particularly beneficial when driving high-efficiency speakers or multi-amplifier systems that demand high purity in mid and high frequencies. The power supply features a robust 400 VA transformer enclosed in a casing filled with vibration-absorbing and thermally conductive material to shield the circuit from external interference. Filtering capacity is ensured by two 47,000 μF electrolytic capacitors, each coated to absorb vibrations.

On the rear panel, the A-20V offers a bridge mode switch that converts the stereo amplifier into a powerful monophonic amplifier by feeding opposite signals to the two channels and connecting the speaker between the outputs, delivering up to 160 watts into 4 ohms or 80 watts into 8 ohms. The dual mono position allows using two independent mono amplifiers, ideal for driving a center woofer or bi-amped systems separating low and high frequencies.

The ACCUPHASE A-20V features balanced input terminals that provide excellent immunity to external interference, maintaining signal purity even with long cables. A large analog power meter with logarithmic compression enables precise signal level monitoring and includes a switch to turn the meter and its illumination on or off. Signal-carrying components are made of high-purity copper with gold plating on the printed circuit board traces and input/output terminals to enhance sound quality and reduce contact resistance.

The speaker terminals, made from solid brass and gold-plated, are particularly robust and equipped with insulating caps to ensure reliable and secure connections, even with heavy-gauge cables. Switching between stereo, dual mono, and bridge modes is easy and quick thanks to a practical selector on the rear panel, making the A-20V extremely versatile for any sound setup.

The ACCUPHASE A-20V combines advanced technology and meticulous craftsmanship to deliver linear power, stability, and natural, immersive sound quality, perfect for the most demanding audiophiles.

Technical specifications:

• Continuous average output power (20 - 20,000 Hz): 180 watts per channel at 2 ohms; 140 watts per channel at 4 ohms; 120 watts per channel at 8 ohms; 160 watts at 4 ohms (monophonic); 180 watts at 8 ohms (monophonic)
• Total harmonic distortion: 0.05% in stereo at 2 ohms; 0.02% in stereo at 4 to 16 ohms; 0.02% in monophonic at 4 to 16 ohms (bridge connection)
• Intermodulation distortion: 0.003%
• Frequency response: at rated output 20 - 20,000 Hz ±0.2 dB; at 1 watt output 0.5 - 160,000 Hz ±3.0 dB
• Gain (GAIN selector in MAX position): 28.0 dB in stereo and monophonic
• Output load impedance: stereo 2 - 16 ohms; monophonic 4 - 16 ohms
• Damping factor: stereo 120; monophonic 60
• Input sensitivity (with 8-ohm load): stereo 0.50 V for rated output; 0.11 V for 1 watt; monophonic 1.00 V for rated output; 0.11 V for 1 watt
• Input impedance: balanced 40 kΩ; unbalanced 20 kΩ
• Signal-to-noise ratio (A-weighted): 110 dB with input shorted at rated output
• Output level meters: NORMAL mode –40 to +3 dB with direct watt reading; –20 dB mode –60 to –17 dB with direct watt reading; logarithmic compression; on/off switch
• Power requirements: 120 V / 230 V AC, 50/60 Hz (as indicated on rear panel)
• Power consumption: 160 watts idle; 250 watts according to IEC-65 standard
• Maximum dimensions: width 475 mm; height 170 mm; depth 426 mm
• Weight: 22.6 kg