Technics SE-9200
¥ 120,000 (around 1975)
Commentary
Stereo power amplifier with 4-stage output impedance switching.
The output impedance can be switched to 4 levels of 0.08 Ω (normal), 0.8 Ω, 2.7 Ω and 8 Ω. The circuit is bridge type with no gain change.
By changing the output impedance, the damping factor can be changed and the performance of the speaker can be further extracted. In the case of an 8 Ω speaker, it can be switched to 100, 10, 3 or 1.
The circuit configuration of the power amplifier section is based on a differential-amplified full-stage coupled complete complimentary service OCL, and various devices are devised to realize low distortion and high stability amplification.
An emitter follower is inserted in the next stage of the differential amplifier to increase the amplification degree of the first stage to improve the SN ratio and optimize the impedance matching up to the pre-drive stage to prevent the generation of distortion.
In the predrive stage, the bootstrap capacitor is removed to improve low-frequency stability, and the output stage stability is also improved.
The power supply unit uses a constant voltage power supply of ± 42 v for the voltage amplifier stage and a large capacity transformer and 10,000 μ F capacitor for the output stage.
Equipped with an output direct reading peak detection type power meter.
This meter can adjust the meter range in 3 stages, and the output movement can be read with higher accuracy.
A protective circuit unique to Technics by relay is adopted.
In this circuit, there is no relay contact resistance in the signal system, and the sound quality does not deteriorate even after many years of use.
As a shock sound prevention circuit when the power is ON, a timing circuit composed of a Zener diode of a common emitter power supply of differential amplification, a diode, a capacitor, and a resistor is mounted.
Model Rating
Type | Stereo power amplifier |
Effective power | Single-channel, 1 kHz : 110W/110W (4 Ω) 83W/83W (8 Ω) Both channels, 1 kHz : 103W + 103W (4 Ω) 82W + 82W (8 Ω) Both channels, 20 Hz to 20 kHz : 93W + 93W (4 Ω) 76W + 76W (8 Ω) |
Total harmonic distortion factor | 0.08% |
Output bandwidth | 5 Hz ~ 70 kHz -3dB (both channels, 8 Ω) |
Frequency characteristic | 5 Hz ~ 100 kHz + 0 -3dB |
Signal-to-noise ratio | 110dB |
Residual noise | 0.3mV |
Damping factor | 4 Ω : 50, 5, 1.5, 0.5 8 Ω : 100, 10, 3, 1 |
Load impedance | Main or Remote : 4 Ω ~ 16 Ω Main + Remote : 8 Ω ~ 16 Ω |
Input Sensitivity / Impedance | 1V/40k Ω |
Pwer | 100 VAC, 50Hz/60Hz |
Power consumption | 180W |
External dimensions | Width 450x Height 173x Depth 380.5 mm |
Weight | 15kg |