Aurex SB-650
¥ 67,800 (around 1978)
Commentary
This DC pre-main amplifier is multi-functional yet has a simple design and excellent operability.
The equalizer is connected in parallel on the first stage and in a 3-stage direct connection mode with the output stage of the emitter follower for class A operation.
High-precision parts are used for low-noise transistors and RIAA devices to improve sound quality.
The output stage of the power amplifier realizes 50W + 50W by single push-pull using a high voltage power transistor.
The circuit configuration is a two stage Darlington connection pure complimentary service OCL system with a dual FET at the first stage and a constant current load. The input is ICL and is a DC-configuration through the whole.
The 3-stage direct-coupled tone control amplifier uses NF type, and by using volume with 11-point click, accurate change characteristics can be obtained.
When the tone defeat switch is turned ON, the tone element jumps and operates as a flat amplifier.
Equipped with a newly designed protective circuit, it protects the power transistor from shorting of the output terminal, protects the speaker from DC generation, and automatically returns to the normal state when the cause is removed.
A one touch fader is incorporated as an advanced function of the muting switch.
When the power supply is turned on, the volume indicator will light. If you press the OUT side of the FADER when you want to reduce the volume, the electronic circuit will gradually reduce the volume. When you have finished reducing the volume, the volume indicator will turn off. To increase the volume, press FADER IN to automatically raise the volume to the first set volume.
Equipped with a loudness switch and subsonic filter.
By storing all the rarely used knobs in the sealing pocket, the multi-functional amplifier realizes simple operation.
.JPG)
Model Rating
| Type | Pre-main amplifier | ||||
| Power Amplifier Unit | |||||
| Continuous output (both channel drive) |
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| Total harmonic distortion factor | 0.02% (at rated output) 0.02% (at 5W output) |
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| Cross modulation distortion factor | 0.02% (at rated output) 0.02% (at 5W output) |
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| Frequency characteristic | DC ~ 100 kHz + 0 -1dB (Aux) | ||||
| Output Bandwidth (IHF 0.02%) | 5 Hz ~ 50 kHz (8 Ω, both channel drive) | ||||
| Damping factor | 40 or more | ||||
| Speaker impedance | 4 Ω ~ 16 Ω (8 Ω ~ 16 Ω only for A + B) | ||||
| Preamplifier Section | |||||
| Input Sensitivity / Impedance | Phono : 2.5mV/47k Ω Tuner, Aux, Tape play : 150mV/50k Ω |
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| Recorded output | Tape rec:150mV | ||||
| Frequency characteristic | 5 Hz ~ 100 kHz + 0 -1dB (Aux) | ||||
| Total harmonic distortion factor | 0.02% | ||||
| Tone control | Bass : ± 10 dB (100 Hz) Treble : ± 10 dB (10 kHz) |
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| Filter | Subsonic : 16 Hz, 6dB/oct. | ||||
| Equalizer deviation | 20 Hz to 30 kHz ± 0.3 dB | ||||
| Phono maximum allowable input | 250 mv (RMS-1kHz, THD 0.02%) | ||||
| Signal-to-noise ratio (IHF-A network, short circuit) | Phono:85dB Aux:100dB |
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| <General> | |||||
| Semiconductor used | Transistor : 46 IC : 3 Diode : 28 pcs LED : 3 pcs |
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| Power supply voltage | 100 VAC, 50Hz/60Hz | ||||
| Power consumption | 130W | ||||
| External dimensions | Width 420x Height 115x Depth 317 mm | ||||
| Weight | 9kg | ||||