Accuphase A-20V (1995)
Pure Class-A stereo power amplifier with dual-mono design and MOS-FET output stage, released in June 1995.
Overview
The Accuphase A-20V is a pure Class-A stereo power amplifier made in Japan by Accuphase Laboratory, Inc. It came out in June 1995 as part of the "V" series, along with the A-30V, A-50V, and A-100V. Accuphase pitched it as a "low-power, high-current" amplifier. It delivers 20 watts per channel into 8Ω in stereo. Bridged for monaural operation, it gives up to 160 watts into 4Ω. It has both balanced and unbalanced inputs, and it takes speaker loads from 2Ω to 16Ω in stereo and 4Ω to 16Ω in monaural mode.
Specifications
| Power Output (Stereo, 8Ω) | 20 watts per channel |
| Power Output (Stereo, 4Ω) | 40W/ch |
| Power Output (Stereo, 2Ω) | 80W/ch |
| Power Output (Monaural, 8Ω) | 80W |
| Power Output (Monaural, 4Ω) | 160W |
| Frequency Response (Rated Output) | 20Hz to 20,000Hz, +0 -0.2dB |
| Frequency Response (1W Output) | 0.5Hz to 160,000Hz, +0 -3.0dB |
| Total Harmonic Distortion (Stereo, 4–16Ω) | 0.02% |
| Total Harmonic Distortion (Stereo, 2Ω) | 0.05% |
| IM Distortion | 0.003% |
| Damping Factor (Stereo) | 120 |
| Damping Factor (Monaural) | 60 |
| Gain | 28.0 dB |
| Input Sensitivity (Stereo, 8Ω, Rated Output) | 0.50V |
| Input Sensitivity (Stereo, 8Ω, 1W Output) | 0.11V |
| Input Sensitivity (Monaural, 8Ω, Rated Output) | 1.00V |
| Signal to Noise Ratio (A-weighted) | 110dB |
| Input Impedance (Balanced) | 40kΩ |
| Input Impedance (Unbalanced) | 20kΩ |
| Dimensions (WHD) | 475 x 170 x 426 mm |
| Net Weight | 22.6 kg |
| Power Supply | AC100V, 50Hz/60Hz |
| Power Consumption (No Input) | 160W |
| Power Consumption (8Ω Rated Output) | 180W |
Design
The A-20V runs pure Class-A with dual-mono construction, so each channel is amplified independently. The circuit is a current feedback design built from discrete components. The output stage is a Power MOS-FET in a 3-parallel push-pull configuration. The power supply uses a large 400VA transformer to keep high-current delivery stable. The front panel has a champagne/gold faceplate and dual analog power meters of the logarithmic compression type. They read from -40dB to +3dB in NORMAL mode and from -60dB to -17dB in -20dB mode.
Context
The A-20V belongs to Accuphase's "V" series, which stresses high-current delivery despite modest rated power. Accuphase Laboratory, Inc. was founded in late 1972 by Jiro Kasuga, a former Kenwood engineer.
Market
Current market prices for the A-20V vary by region. Listings show approximately €3,290, ¥198,000, and $2,193 USD.
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Service Manuals, Schematics & Catalogs
- Catalog (1991) — archive.org
- Catalog (1990) — archive.org