Accuphase PRO-20
¥ 780,000 (released in January 1994)
Commentary
A natural air-cooling type stereo power amplifier developed as a studio amplifier.
10 parallel push-pull configuration is adopted for the output stage, and 20 MOS-FETs with allowable loss power of 120W per channel are adopted.
With this configuration, the power load per pair for 8 Ω load is only 5W, and the MOS-FET MOS-FET with excellent DC characteristics can be used without difficulty, and high-quality signal power can be supplied to speakers.
It can be used as a balanced monaural power amplifier by the bridge connection switch on the rear panel side.
AccuPhase's unique balanced differential pure complimentary service push-pull circuit is used for the input circuit, and FET buffers with high input and low output impedance are used for both positive and negative input circuits.
Moreover, by modularizing this input circuit with a hybrid IC, temperature and noise characteristics are improved, and high reliability and long-term stability are obtained.
All signal paths are gold-plated.
The printed circuit board of the signal path is gold-plated to reduce skin resistance to improve sound quality. The oxygen-free copper bus board for connecting the outputs and the outputs terminals are also gold-plated.
The power supply is equipped with a high-power large-capacity toroidal transformer of 1,000 VA and a large-capacity filter capacitor of 56,000 μ Fx2.
It is a naturally air-cooled type using a large heat sink made of aluminum die cast, and a quiet amplifier is realized by eliminating fan noise.
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Model Rating
| Type | Stereo power amplifier |
| Continuous Average Output (20 Hz to 20 kHz) | Stereo type (both channel operation) 300W + 300W (2 ohm load) 200W + 200W (4 ohm load) 100W + 100W (8 Ω load) Monophonic Specification (Bridge Connection) 600W (4 Ω load) 400W (8 Ω load) |
| Total harmonic distortion factor | Stereo type (both channel operation) 0.05% (2 Ω Load) 0.02% (4 Ω ~ 16 Ω Load) Monophonic Specification (Bridge Connection) 0.02% (4 Ω ~ 16 Ω Load) |
| IM distortion factor | 0.003% |
| Frequency characteristic | 20 Hz ~ 20 kHz + 0 -0.2 dB (Continuous Average Output, Level Control MAX) 0.5 Hz ~ 160 kHz + 0 -3.0 dB (at 1W Output, Level Control MAX) 0.5 Hz ~ 110 kHz + 0 -3. d0B (at 1W output, level control -6dB) |
| Gain | 28.0 dB (for stereo / monophonic specifications) |
| Load impedance | Stereo specification : 2 Ω ~ 16 Ω Monophonic Specification (Bridge Connection) : 4 Ω ~ 16 Ω |
| Damping factor | Stereo specification : 160 Monophonic specification (bridge connection) : 140 |
| Input sensitivity (8 Ω load) | Stereo specification 0.80 V (at continuous average output) 0.11 V (at 1W output) Monophonic Specification (Bridge Connection) 1.59 V (at continuous average output) 0.11 V (at 1W output) |
| Input impedance | Balance : 40k Ω Unbalanced : 20k Ω |
| S/N (A correction) | 110 dB (Input Short, Continuous Average Output) |
| Input terminal | RCA phono jack Cannon Connector : XLR-3-31 Equivalent 1 : Grand 2 : Hot 3 : Cold |
| Pwer | AC110V/117V/220V/240V, 50Hz/60Hz |
| Power consumption | 310W (no input) 550W (Electrical Appliance and Material Control Law) 375W (at 8 Ω load rated output) |
| Maximum external dimensions | Width 475x Height 238.5x Depth 548 mm |
| Weight | 46.8kg |
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