Audio Database

The

SANSUI AU-555
37,500yen(May, 1968 release)

Description
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The Integrated Amplifier which repeated not only a sound circuit design but the audition testing, and was investigated and developed.

Whole page silicon transistors, such as a low-noise silicon transistor sorted out, are adopted as a power transistor especially in the equalizer circuitry including using the epitaxial silicon transistor.

The SEPP-ITL-OTL scheme of the complimentary darlington circuit which uses an epitaxial type silicon transistor for a power transistor is adopted.

The power transformer which demonstrated the transformer technology of the SANSUI to the transformer at full, and was specially designed for transistor amplifier is adopted.

The dumping factor carries the switchpoint changed to two steps, High (45) and Low (12), so that the property of any speaker systems may be suited.

NF type tone control by a low noise silicon transistor is used for a middle amplifier part.
Moreover, loud sound, the bass, and also the right-and-left channel carry the tone circuitry which can be adjusted independently.

The frequency characteristic, distortion, and S/N are improved with constituting all the amplifying circuits from NF amplifier.

The pure electronic formula PSC (protection) circuitry original with an SANSUI is adopted so that a power transistor may not be damaged, even if it makes an output-terminal short-circuit accidentally.
Furthermore, it is a double security unit which certainly secures a safeness combining an immediate judgment fuse in a power transistor.

It is designed so that a preamplifier and a main amplifier can use it separately.

The loudness control, a tapes monitor, a headphone jack, a muting circuit which can carry out the play monitor of the recorded source while recording, etc. are carried.

Two speaker outputs, A and B, are carried and it can reproduce independently or simultaneous.


Rating of a mode
Form Solid-state Integrated Amplifier
<Power amplifier part>
Output power
Music power (IHF) : 60W}1dB (4ohm)
50W}1dB (8ohm)
Effective output : 25/25W}1dB (4ohm)
20/20W}1dB (8ohm)
THD 0.5%
Cross modulation distortion (60Hz:7000Hz=4:1) 0.8%
Power Band Width (IHF) 20Hz - 30000Hz (distortion 0.5%)
Frequency characteristic 20Hz - 80000Hz, }1dB (by normal output)
A hum and a noise (IHF) Closed circuit: 100dB
Input sensitivity/impedance 1V/100kohm
Dumping factor High:45
Low:12
Load impedance 4ohm-16ohm
<Preamplifier part>
Output voltage Maximum output voltage: 3V
Output-power voltage: 1V (150ohms)
THD 0.1% (Output-power voltage)
Frequency characteristic 20Hz - 50000Hz, }1dB
A hum and a noise (IHF) Volume min: 100dB
Phono1, 2 (closed circuit):80dB
Tape Head 19cm/sec.(closed circuit):75dB
AUX1, 2 (open circuit):80dB
Input sensitivity/impedance Phono1:2mV/47kohm
Phono2:2mV/100kohm
Tape Head 19cm/sec.:1.5mV/200kohm
MIC: 3.5mV / 10kohm
AUX1:200mV/100kohm
AUX2:140mV/100kohm
Tape Monitor: 150mV / 100kohm
Sound-recording output Phono1, 2:37.5 dB
Tape Head 19cm/sec.:40dB
MIC:32.5dB
Control
Bass: 20Hz, }16dB
Treble: 20kHz, }13dB
Loudness control (volume 30dB) : 50Hz, +8dB
10kHz, +2.5dB
High filter : 20kHz-10dB
Low filter : 30Hz-12dB
Muting : - 20dB (20Hz - 20000Hz)
<Synthesis>
Transistor 2SA561x2, 2SC281x2, 2SC369x2
2SC646x4, 2SC733x2, 2SC734x4
2SC458LGx2, 2SC458Lx4
A total of 22 stones
Diode 10D-1x4, IN60x2
A total of six stones
Thermistor DS410x4
S.C.R. 2SF-656x1
Power source AC100V, 117V, 220V and 240V, 50Hz/60Hz
Power consumption 120W (maxima)
Dimensions Width 382x height 111x depth of 267mm
Weight 7.9kg