Power Amplifier (Class-A, 2x60w).
Inheriting many outstanding technology features of the Accuphase A-200, the A-70 represents a full model change from the A-65, ready to take its place as the ultimate pure class A stereo power amplifier. While reflecting this tradition, the A-70 also implements latest technology such as the ultra low-noise instrumentation amplifier principle realised in a discrete configuration, along with optimised signal input and power amplification stages, resulting in an astonishing 127 dB S/N ratio (at -12 dB gain), surpassing even the formidable earlier Accuphase stereo amplifier lineup.
The output stage of the A-70 features power MOS-FETs renowned for their excellent frequency response, sonic performance, and superior reliability. In the output circuitry, ultra-heavy-gauge edgewise coils with a surface area more than three times larger than conventional units, combined with MOS-FET switches are used in place of relays, to eliminate mechanical contacts and improve long-term reliability. Top-grade materials, sophisticated circuit pattern technology, and various other measures result in low impedance and enable the realisation of a damping factor of 800, which represents a two-fold improvement over the A-65.
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- Pure Class A operation delivers quality power: 60 watts x 2 into 8 ohms
- Power MOS-FET output stage features 10-parallel push-pull configuration and delivers linear high power progression to ultra-low 1-ohm impedances
- Ultra low-noise instrumentation amplifier principle used in input stage
- Amplification stage implements further evolved MCS+ topology
- Current feedback principle combines stable operation with outstanding sound quality
- Bridged mode allows upgrading to true monophonic amplifier
- Two selectable meter types: digital power meters showing true power values and bar graph indicators
- Continuous Average Output Power (20–20,000 Hz): Stereo operation (both channels driven) - 480 watts per channel into 1 ohm, 240 watts per channel into 2 ohms, 120 watts per channel into 4 ohms, 90 watts per channel into 8 ohms. Monophonic operation (bridged connection) - 960 watts into 2 ohms, 480 watts into 4 ohms, 240 watts into 8 ohms.
- Total Harmonic Distortion: Stereo operation (both channels driven) - 0.07% with 2 ohm load, 0.03% with 4 to 16 ohm load. Monophonic operation (bridged connection) - 0.05% with 4 to 16 ohm load
- Intermodulation Distortion: 0.01%
- Frequency Response: At rated output: 20 – 20,000 Hz +0, -0.2 dB. At 1 watt output: 0.5 – 160,000 Hz +0, -3.0 dB
- Gain: 28.0 dB (with GAIN selector at MAX) (Stereo and monophonic operation)
- Gain Selection: MAX, -3 dB, -6 dB, -12 dB
- Output Load impedance: Stereo operation - 2 to 16 ohms. Monophonic operation: 4 to 16 ohms
- Damping Factor: 800
- Input Sensitivity (with 8-ohm load, GAIN selector in MAX position): Stereo operation - 0.87 V for rated continuous average output (60 W). 0.11 V for 1 watt output. Monophonic operation - 1.74 V for rated continuous average output (240 W). 0.11 V for 1 watt output
- Input Impedance: Balanced - 40 kilohms. Line - 20 kilohms
- Signal-to-Noise Ratio (A-weighted, input shorted): 121 dB (GAIN selector at MAX), 127 dB (GAIN selector at -12 dB) At rated continuous average output
- Output Level Meters (digital indication and bar graph): Digital meters: 5-digit indication, selectable range (10 W / 100 W / 1000 W). Bar graph meters: 32-point scale. Hold time: 1 second/, switchable. ＊Display off setting provided.＊Monophonic operation: same value displayed for left/right.
- Power Requirements: AC 120 V/230 V, 50/60 Hz (Voltage as indicated on rear panel)
- Power Consumption: 280 watts idle. 530 watts in accordance with IEC 60065
- Maximum Dimensions: Width 465 mm, Height 238 mm, Depth 515 mm
- Mass: 44.3 kg net, 54.0 kg in shipping carton