Pioneer SA-710 (c. 1973)
A high-fidelity integrated amplifier from Pioneer’s renowned SA series, featuring precision RIAA equalization and robust OCL power design.
Overview
The Pioneer SA-710 is a stereo pre-main amplifier released around 1973, part of Pioneer's "Famous Series" alongside the SX and SPEC lines. It combines a low-noise preamplifier with a powerful OCL-based power amplifier, designed for high fidelity and stability. The unit features comprehensive input options including dual phono, MIC, tuner, AUX, and tape monitoring, with precision-tuned equalization and independent tone controls.
Specifications
| Product type | Stereo pre-main amplifier (integrated amplifier) |
| Power Amplifier Unit Circuit system | Pure complimentary service OCL |
| Effective power 20 Hz to 20000 Hz, both channel drive | 20W + 20W (8 Ω) |
| Effective power 20 Hz to 20000 Hz, both channel drive | 24W + 24W (4 Ω) |
| 1 kHz, both channel drive | 22W + 22W (8 Ω) |
| 1 kHz, both channel drive | 30W + 30W (4 Ω) |
| 1 kHz, single-channel drive | 25W/25W (8 Ω) |
| 1 kHz, single-channel drive | 36W/36W (4 Ω) |
| Harmonic distortion factor Effective power | 0.5% or less |
| Harmonic distortion factor 1W output | 0.05% or less |
| Cross modulation distortion factor Effective power | 0.5% or less |
| Cross modulation distortion factor at 1W output | 0.1% or less |
| Output Bandwidth (IHF, both channel drives) | 5 Hz ~ 70 kHz (Distortion Factor 0.5%) |
| Frequency characteristic | 7 Hz to 80 kHz, +0 -1dB |
| Input Sensitivity / Impedance Power Amp In | 500mV/50k Ω |
| Output terminal Speaker | A, B, A + B (4 Ω ~ 16 Ω) |
| Output terminal Head Phones | 4 Ω ~ 16 Ω |
| Damping factor (1 kHz, 8 Ω) | 40 or more |
| S/N | 90 dB or more (IHF, short circuit A network) |
| Residual noise (8 Ω, pre + power amplifier) | 1 mV (0.13 μW) or less |
| Subsonic filter | 5Hz (12dB/oct) |
| Preamplifier Section Circuit system Equalizer amplifier | 3-stage direct connection NF type |
| Preamplifier Section Circuit system Control amplifier | First stage FET, NF type |
| Input Sensitivity / Impedance Phono1 | 2.5mV/50k Ω |
| Input Sensitivity / Impedance Phono2 | 2.5mV/50k Ω |
| Phono maximum allowable input (rms/p-p) | 190mV/530mV |
| Input Sensitivity / Impedance MIC | 2.0mV/50k Ω |
| Input Sensitivity / Impedance Tuner | 150mV/100k Ω |
| Input Sensitivity / Impedance AUX1 | 150mV/100k Ω |
| Input Sensitivity / Impedance AUX2 | 150mV/100k Ω |
| Input Sensitivity / Impedance Tape Monitor1, 2 | 150mV/100k Ω |
| Input Sensitivity / Impedance Tape Monitor2 (DIN) | 150mV/100k Ω |
| Output Level / Impedance Tape Rec1, 2 | 150 mV |
| Output Level / Impedance Tape Rec2 (DIN) | 30mV/80k Ω |
| Output Level / Impedance Pre Out | 500mV/1.5k Ω |
| Harmonic distortion factor (20 Hz to 20 kHz) | Not more than 0.1% |
| Frequency characteristic Phono (RIAA deviation) | 30 Hz to 15 kHz, ± 0.2 dB |
| Frequency characteristic MIC | 15 Hz to 10 kHz, +0 -1dB |
| Frequency characteristic Tuner, AUX, TapeMonitor | 15 Hz to 30 kHz, +0 -1dB |
| Tone control Bass | ± 10 dB (100 Hz) |
| Tone control Bass Turnover frequency | 200 Hz, 400 Hz |
| Tone control Treble | ± 10.5 dB at 10 kHz |
| Tone control Treble Turnover frequency | 5 kHz, 2.5 kHz |
| Loudness contour at volume -40dB | +10 dB at 100 Hz, 6 dB at 10 kHz |
| S/N (IHF, short circuit A network) Phono | 80 dB or more |
| S/N (IHF, short circuit A network) MIC | 70 dB or more |
| S/N (IHF, short circuit A network) Tuner, AUX, Tape Monitor | 90 dB or higher |
| Muting | -20dB |
| Semiconductor used | FET: 2, Transistor: 33, Diode and others: 24 |
| Power supply voltage | 100 VAC, 50Hz/60Hz |
| Rated power consumption | 55W |
| Maximum Power Consumption | 180W |
| Power outlet | Power switch interlock 1, non-interlock 2 |
| External dimensions | Width 430 x Height 138 x Depth 341 mm |
| Weight | 10.1kg |
Design
The SA-710 uses a fully direct-coupled pure complimentary service OCL system across all stages, ensuring high stability and low distortion. The phono equalizer employs a 3-stage direct-coupled NF amplifier with a low-noise PNP transistor in the first stage, while the control amplifier uses an FET for high input impedance and consistent noise performance across volume settings. Precision 1% nichrome and 2% styrene capacitors are used in the RIAA feedback network to minimize playback curve deviation. The amplifier includes a subsonic filter (5 Hz, 12dB/oct), independent bass and treble turnover switches, and a one-touch tone defeat. A large heatsink, matched PNP/NPN transistors, current limiting, and an electronic protection circuit with relay and indicator ensure thermal stability and safety. Dual tape monitor circuits and A/B speaker terminals support flexible system configuration.
Context
The SA-710 belongs to Pioneer's "Famous Series," a lineup that includes the high-end SX and SPEC series, indicating its position as a premium integrated amplifier during the early 1970s.
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