Technics SU-A707
A late-1980s Technics integrated amplifier using the company's distinctive Class AA topology — a parallel-amplifier design that separates voltage gain from current delivery to combine low-feedback linearity with high power output.
Overview
The SU-A707 is part of Technics' Class AA integrated amplifier lineup, contemporary with the SU-A800 and SU-A900. Class AA is a Technics-specific topology — not the same as Class A or A/B — that uses two parallel amplifier stages: a "voltage amplifier" stage that handles signal gain with low feedback and tight linearity, and a "current amplifier" stage that handles output current independently. The two stages are bridged through a special bridge circuit that lets the voltage stage operate without seeing the power-amp load's reflected complexity.
The acoustic claim was that Class AA eliminated the trade-off between low-feedback linearity (good for sound quality) and high-power output (which usually requires more feedback). In subjective listening tests, Technics Class AA amps from this era are generally regarded as cleaner and more transparent than typical Class A/B integrateds at the same price point.
Specifications
| Type | Class AA integrated amplifier |
| Power | ~70 W/ch RMS, 8Ω, both channels driven |
| THD at rated power | 0.005% |
| Frequency response | 5 Hz – 100 kHz (±1 dB) |
| S/N ratio | ~108 dB (Aux), ~80 dB (Phono MM) |
| Phono input | MM + MC |
| Inputs | Phono ×2, Tape ×2, CD, Aux, Tuner |
Applications and Legacy
Late-1980s home stereo systems, Japanese-market enthusiast hi-fi. Working examples trade for $200-400. The Class AA circuit topology aged well — none of the legendary failure modes of some 1980s designs apply, and the unit responds well to standard service (electrolytic refresh, switch cleaning).
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