Solid State Control Amplifier
In introducing the Au-555, Sansui sets still another "first" in its long list of
audio innovations: the first time a truly professional control amplifier of
Sansui quality has been available in the medium power price range.
The AU-555 incorporates many of the features of Sansui's larger AU series
amplifiers, including an all silicon solid state design, professional
arrangement of controls and an black control panel. At the same time, it offers
several distinctive features of its own. In performance, a total music power
output of 60 watts, a power bandwith from 20 to 30,000 Hz, and a distortion
factor of only 0,5% are made possible by utilizing special SEPP-ITL-OTL
circuitry. Pre- and main amplifier sections designedfor independent usage, two
adjustable speaker damping factors, a 4-position speaker selector switch, and
four outputs and seven inputs give it almost unlimited versatility. These are
only a few of the many features offered by the new AU-555 - features that make
it the first uncompromised control amplifier in the medium power range.
All Silicon Solid-State Design
Silicon transistors in all stages of the amplifier assure lower distortion and a
higher signal-to-noise ratio even at low power levels. They also provide greater
stability against high temperatures. This results in a greater dynamic range for
the highest standards of sound reproduction with excellent linearity.
Most Advanced Circuitry
The transformerless arrangement (SEPP-ITL-OTL) of a complementary Darlington
circuit and the use of epitaxial silicon power transistors provide the music
power of 60 watts, continous power of 25/25 watts with less than 0,5% harmonic
distortion and a power bandwith of 20 to 30,000 Hz.
NF-Type Bass and Treble Control
Expensive NF-type tone controls incorporate low-noise silicon transistors for
minimum distortion (only 0,1%) These controls consist of two separate knobs each,
one for each channel, for more minute adjustment.
Matchless Appearance
The extruded front panel, satin-black face, and professional control arrangement
are inherent family features of Sansui's entire AU control amplifier series.
All-Printed Circuit
Printed circuits in all stages of the amplifier greatly improve the channel
separation, stability and reliability of the AU-555.
Newly-Developed Power Transformer
A
new power transformer, designed and manufactured especially for transistors at
Sansui's own factory, assures better power regulation without hum from the
source.
Damping Factor Selector Switch
A
2-position damping factor selector switch (High 45 and Low 12) allows matching
the AU-555's damping factor with the characteristics of any speaker system.
Negative Feedback Amplifier
Negative feedback amplifiers are used in all stages from the first to the final
for appreciable improvements in frequency response, signal-to-noise ratio and
distortion. The main amplifier has a frequency response of 20 to 100,000 Hz +/-1
dB. The preamplifie output has a distortion factor of less than 0,1% at the
rated output voltage of 1 volt.
Double Protection for Power Transistors
Sansui's exclusive electronic protective devices prevent damage to the power
transistors if an accidental short should occur. in addition, the AU-555 is
equipped with quick-acting fuses, which protect the power transistors in case of
overloads.
Independent Pre- and Main Amplifiers
Both pre-and main amplifier sections are designed to be used independantly for
more versatility.
Four Outputs and Seven Inputs
Yhe AU-555 is provided with all the outputs and inputs of the largest amplifiers:
preamp, tape rec., and two speaker outputs, two phono,tape head,microphone and
three other inputs
Two Phono Inputs
The AU-555 is provided with two Phono inputs. phono 1 and 2 have the input
impedance of 47 kohms and 100 kohmsrespectively. Either can be used depending on
preference. Generally a crtridge connected to the 47 kohms input produces a soft
and mild tone. Connected to the 100 kohms input, it delivers tones with accented
high frequencies.
Specifications AU-555
Audio
Section
Power
Output (at rated distortion)
Music
Power (IHF):
60 watts ±1 dB into 4 Ω
at 1,000 Hz;
50 watts ±1 dB into 8 Ω
at 1,000 Hz
Continuous Power (each Channel):
25/25 watts ±1 dB into 4 Ω
20/20 watts ±1 dB into 8 Ω
Total
Harmonic Distortion: less than 0,5% at rated power output
Intermodulation Distortion (60 Hz : 7,000 Hz = 4:1 SMPTE method): less than
0,8%
Power bandwidth (IHF): 20 to 30,000 Hz at 8
Ω (0,5% distortion)
Load Impedance: 4 Ω
to 16 Ω
Frequency Response (at normal listening level): 20 to 80,000 Hz, ±1 dB
Input
Sensitivity: 1V at rated output
Input Impedance: 100 kΩ
Damping Factor: 12 and 45 at 8 Ω
load
Channel Separation (at rated output 1,000 Hz): better than 50 dB
Hum
and Noise (IHF): better than 100 dB
Input
Sensitivity / Impedance (1,000 Hz for rated output):
Phono 1: 2 mV/ 47 kΩ
Phono 2: 2 mV/100 kΩ
Tape head: 1,5 mV/200 kΩ
Aux 1: 200 mV/100 kΩ
Aux 2: 140 mV/100 kΩ
Microphone: 3,5 mV/ 10 kΩ
Tape monitor: 150 mV/ 100 kΩ
Recording Output (at rated input): 140 mV
Controls
Bass:
+16 dB -16 dB at 20 Hz
Treble:
+13 dB -13 dB at 20 kHz
Loudness: 8 dB at 50 Hz; 2,5 dB at 10 kHz
Filters
Low:
-12 dB at 20 Hz
High:
-10 dB at 20,000 Hz
Muting
(audio): 0 dB, -20 dB
General
Semiconductors: 22 Transistors; 6 Diodes; 4 Thermistor; 1 S.C.R.
Power
Requirements: 100, 117, 220, 240 V 50/60 Hz
Power
Consumption: 120 watts Max.
Dimensions (W x H x D): 382 x 111 x 267 mm
(15" x 4⅜
x 10⅞")
excluding rubber stand and knob
Weight:
7,9 kg (17,4 lbs) net