Technics SU 7700 (1976)
A high-fidelity integrated amplifier from Technics' SU-V series, designed for precision and low distortion.
Overview
The Technics SU-7700 is an integrated amplifier made by Technics, a brand of Matsushita Electric Industrial Co. (now Panasonic). It belongs to the SU-V series and came out around 1976. The focus was clean signal handling and sturdy internal construction. The side-terminal layout connects the terminals straight to the circuit board with no wires, which cuts down on signal degradation. It uses precision components and protective circuitry for stable operation.
Specifications
| Power Amplifier Unit Effective output (both channels) | 1kHz: 70W + 70W (4 Ω) 53W + 53W (8 Ω) 20 Hz to 20 kHz : 50W + 50W (8 Ω) |
| Total harmonic distortion factor | 0.06% |
| Output Bandwidth (both channels, 8 Ω) | 8 Hz to 55 kHz -3dB |
| Residual noise | 0.6mV |
| Damping factor | 60 (8 Ω) |
| Load impedance | Main or Remote : 4 Ω ~ 16 Ω Main + Remote : 8 Ω ~ 16 Ω |
| Preamplifier Section Input Sensitivity / Impedance | Phono : 2.5mV/47k Ω Tuner, Aux, Tape1, 2 : 150mV/47k Ω |
| Phono Maximum Input (1 kHz, RMS) | 150mV |
| Signal-to-noise ratio (IHF-A) | Phono:78dB Tuner, Aux : 97 dB |
| Frequency characteristic | Phono : RIAA standard curve ± 0.2 dB Aux : 5 Hz to 80 kHz + 0 -3dB |
| Tone control | Bass : 50 Hz, ± 12 dB Treble : 20 kHz, ± 12 dB |
| Filter EQ | Subsonic : 30 Hz, -12dB/oct. High : 8 kHz, -6dB/oct. |
| Output voltage | Tape1 and 2 : 150 mV |
| Power | 100 VAC, 50/60Hz |
| Power consumption | 122W |
| External dimensions | Width 410x Height 140x Depth 315 mm |
| Weight | 7.2kg |
Design
The SU-7700 is a pre-main amplifier with a side-terminal structure. Input signals go directly to the printed circuit board without wires, which keeps the signal path straight. The equalizer circuit is an IC configuration with differential amplification via a current mirror load, plus an emitter follower output stage with constant current load. The equalizer uses ±1% metal film resistors and ±2% polypropylene capacitors. The main amplifier's first stage is a differential amplifier with a paired transistor in one package and a current mirror load. The power transistors are high-capacity complementary types, chosen for low distortion and noise. A protective and muting circuit uses relays to suppress power-on/off noise. The power supply has a high-density winding transformer and a 10,000 μF electrolytic capacitor. The preamplifier gets a ±2 constant voltage supply built with transistors or Zener diodes. The subsonic filter uses an NF loop in the equalizer circuit. Separate tape monitor and recording selectors let you dub while playing other sources. The volume control is a 41-point step type. The tone control uses a newly developed potentiometer that disconnects the signal at the midpoint, and the tone circuit uses the NF circuit of the main amplifier. The power meter uses germanium diodes for better linearity at low output.
Context
The Technics SU-7700 is part of the SU-V series of integrated amplifiers.
Market
The original price was ¥45,800 around 1976.
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