SANSUI AU-555
¥ 37,500 (released in May 1968)
Commentary
This pre-main amplifier was developed not only through acoustic circuit design but also through repeated listening tests.
The power transistor uses an epitaxial silicon transistor and the equalizer circuit uses an all-stage silicon transistor such as a specially selected low-noise silicon transistor.
SEPP-ITL-OTL system of complimentary service Darlington circuit using epitaxial silicon transistor for power transistor is adopted.
The transformer uses a power transformer specially designed for transistor amplifiers, making full use of SANSUI's transformer technology.
The damping factor is equipped with a switch that can be switched between High (45) and Low (12) to suit the characteristics of any speaker system.
The intermediate amplifier uses NF-type tone control with low-noise silicon transistors.
It is also equipped with a tone circuit that can independently adjust the high and low frequencies and the left and right channels.
Frequency characteristics, distortion, and S/N ratio have been improved by configuring all amplifier circuits with NF amplifiers.
SANSUI's proprietary pure electronic PSC (protection) circuit is used to prevent damage to the power transistor even if the output terminal is accidentally shorted.
In addition, a power transistor and a short-cut fuse are combined to create a double-safety device that ensures safety.
The preamp and main amp can be used separately.
It is equipped with a loudness control, a tape monitor that can monitor the recorded source while recording, a headphone port, a muting circuit, etc.
It is equipped with two speaker outputs, A and B, and can be played either individually or simultaneously.
Model Rating
| Type | Solid-state premain amplifier | ||||
| Power Amplifier Unit | |||||
| Rated output |
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| Total harmonic distortion factor | 0.5% | ||||
| Intermodulation distortion factor (60 hz : 7000 hz = 4 : 1) | 0.8% | ||||
| Power Band With (IHF) | 20 Hz ~ 30000 Hz (Distortion Factor 0.5%) | ||||
| Frequency characteristic | 20 Hz to 80000 Hz, ± 1 dB (at normal output) | ||||
| Hum and noise (IHF) | Closed circuit : 100 dB | ||||
| Input Sensitivity / Impedance | 1V/100k Ω | ||||
| Damping factor | High:45 Low:12 |
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| Load impedance | 4 Ω ~ 16 Ω | ||||
| Preamplifier Section | |||||
| Output voltage | Maximum output voltage : 3 V Rated output voltage : 1 V (150 Ω) |
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| Total harmonic distortion factor | 0.1% (Rated Output Voltage) | ||||
| Frequency characteristic | 20 Hz to 50000 Hz, ± 1 db | ||||
| Hum and noise (IHF) | Volume Min : 100 dB Phono1, 2 (closed circuit) : 80 dB Tape Head 19cm/sec. (closed circuit) : 75 dB AUX1, 2 (open circuit) : 80 dB |
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| Input Sensitivity / Impedance | Phono1 : 2mV/47k Ω Phono2 : 2mV/100k Ω Tape Head 19cm/sec. : 1.5mV/200k Ω MIC : 3.5mV/10k Ω AUX1 : 200mV/100k Ω AUX2 : 140mV/100k Ω Tape Monitor : 150mV/100k Ω |
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| Recorded output | Phono1, 2 : 37.5 dB Tape Head 19cm/sec.:40dB MIC:32.5dB |
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| Tone control | Treble : 20 kHz, ± 13 dB Bass : 20 Hz, ± 16 dB |
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| Loudness control (volume -30dB) : | 50 Hz, + 8 dB 10 kHz, + 2.5 dB |
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| High Filter : | 20 kHz, -10dB | ||||
| Low Filter : | 30 Hz, -12dB | ||||
| Muting : | -20dB (20 Hz to 20000 Hz) | ||||
| <General> | |||||
| Transistor | 2 SA 561, 2 SC 281, 2 SC 369 4 x 2 sc 646, 2 x 2 sc 733, 4 x 2 sc 734 2SC458LGx2, 2SC458Lx4 Total 22 koku |
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| Diode | 10D-1x4, IN60x2 Total 6 koku |
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| Thermistor | DS410x4 | ||||
| S.C.R. | 2SF-656x1 | ||||
| Pwer | 100 VAC, 117 V, 220 V, 240 V, 50Hz/60Hz | ||||
| Power consumption | 120W maximum | ||||
| External dimensions | Width 382x Height 111x Depth 267 mm | ||||
| Weight | 7.9kg | ||||