The
AU-555 has long been one of the most attractive control amplifier values in the
medium power field. Now-as the improved AU-555A - it's even more of a buy, with
more power, more features and more style than ever. Take power, for example.
It's up from an ample 60 watts to 33/33 watts at 4 Ω. And now intermodulation distortion as well as total harmonic
distortion are limited to under 0,5%. Take performance. The AU-555A offers tone
quality very nearly on a par with Sansui's 120 watt top-of-the-line AU-999. in
fact, performance generally is quite comparable to that of much larger units
despite the AU-555A's compact size. A triple tone control circuit has also been
added to achieve new standards in trully accurate sound. In addition, there has
been a widening of the power bandwidth to from 20 to 40,000 Hz, and the unit
now is housed in a handsome walnut cabinet. Versatility hasn't been neglected,
either. The new AU-555A features two speaker switches, independently usable
preamplifier and power amplifier sections, five outputs and seven inputs. Add
all those assets together and you begin to appreciate what Sansui means by
"improved". And what the AU-555A can mean you.
Semi-Complementary
SEPP Circuit
The
AU-555A's power amplifier utilizes a semicomplementary SEPP-ITL-OTL Darlington
circuit with all silicon power transistors. It delivers music power (IHF) of 85
watts and continuous power of 33 watts per channel at 4 Ω. Total Harmonic Distortion and Intermodulation Distortion are both
less than 0,5% and the power bandwidth is a wide 20 to 40,000 Hz.
Low-Noise
Preamplifier Section
Carefully
selected low noise silicon transistors are employed in the preamplifier section
to enable the AU-555A to achieve an unprecedented low noise level.
In
performance, that means a greatly expanded dynamic range and increased sound
transparency for pianissimo notes.
Negative
Feedback Amplifiers
Better
frequency response, and better distortion and signal-to-noise characteristics
are achieved by using negative feedback amplifiers in all amplifier stages.
Direct-Coupled
Circuitry
The AU-555A
employs direct-coupled circuitry wherever possible to get around the problem of
poor phase characteristics common to electrolytic capacitors at high
frequencies. But where coupling capacitors are necessary, circuit impedance has
been raised and mylar capacitors employed or mylar capacitors have been used in
parallel for improved response at high frequencies. The human ear can readly
detect the difference.
Triple Tone
Control Circuit
A T.T.C.
system has been added to the AU-555A to achieve the truly accurate reproduction
obtained with variable equalizers. This system enables improved compensation
for room acoustics and for irregularities in program sources. The bass,
midrange and treble circuits can all be controlled in small, significant steps.
Silicon
Transistors Throughout
Exceptional
high-end frequency response and linearity are obtained by using silicon
transistors exclusively.
Separable
Preamplifier and Power Amplifier
The
preamplifier and power amplifier section of the AU-555A can be utilized
separately to from an advanced electronic crossover stereo system. The great
performance potential of each of these amplifier sections can by more fully
exploited through such usage.
Ripple
Filter Power Supply Circuits
Detrimental
hum in high fidelity reproduction has been eliminated in the AU-555A by the use
of ripple filter circuits in the power supplies for the preamplifier and power
amplifier sections. Completely stabilized power supplies are the result.
Two Phono
Input Circuits
The
AU-555A incorporates two 50 k Ω
phonograph input circuits. This permits the connection of two different
cartridges for comparison purposes or to hear different types of music with
varying timbre.
Complete
Accessory Circuit ystem
The
AU-555A's complete range of accessory circuits includes a DIN connector for
connecting a tape recorder or deck; high and low filter circuits; loudness
control circuit, tape monitor circuit which permits monitoring a tape as it is
recorded; headphone jack circuit, and foolproof one-touch type speaker output
terminals.
Attractive
and professional Styling
Housed in a
rich walnut cabinet, the AU-555A has an expensive extrusion front panel and has
been carefully color-treated in black to give it the sophisticated appearance
that is the hallmark of all Sansui professional components.
Specifications AU-555A
Power
Amplifier Section
Power Output
(at rated distortion)
Music Power
(IHF):
80
watts ±1 dB into 4 Ω at 1,000
Hz;
60
watts ±1 dB into 8 Ω at 1,000 Hz
Continuous Power (each
Channel):
33/33
watts ±1 dB into 4 Ω
25/25
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 40,000 Hz
Load
Impedance: 4 Ω to 16 Ω
Frequency
Response (at normal listening
level): 20 to 40,000 Hz, ±1 dB
Input
Sensitivity: 1V at rated output
Input
Impedance: 100 kΩ
Damping
Factor: 50 at 8 Ω load
Channel
Separation (at rated output 1,000 Hz):
better than 60 dB
Hum and
Noise (IHF): better than 100 dB
Preamplifier
Section
Output
Voltage [Maximum/Rated]: 5 V / 1 V
Total
harmonic Distortion: less than 0,1% ata
rated output voltage
Frequency
Response: 20 - 30,000 Hz ±1 dB
Channel
Separation (at 1 kHz rated output voltage):
Phono 1 and
2 : better tahn 45 dB
Tuner and
Aux : better than 50 dB
Hum and
Noise (IHF):
Phono 1 and
2 : better than 70 dB
Tuner and
Aux : better than 80 dB
Input
Sensitivity / Impedance (1,000 Hz for rated output):
Phono
1 and 2 : 2 mV (50 kΩ)
Tape
Mon (Pin) : 180 mV (50 kΩ)
Tape
Rec (DIN) : 180 mV (50 kΩ)
Aux
: 180 mV(50 kΩ)
Recording
Output (at 1 kHz rated input voltage):
Tape Rac
(Pin) : 180 mV
Tape
Recorder (DIN) : 30 mV
Equalizer:
Phono : RIAA NF Type
Mic : flat NF Type
Controls
Bass: +12 dB -12 dB at 30 Hz
Midrange: +5 dB -5 dB at 1,500 Hz
Treble: +10 dB -10 dB at 15,000 Hz
Loudness: +8 dB at 50 Hz; +3 dB at 10 kHz
Filters
Low: -8 dB at 50 Hz
High: -7 dB at 10,000 Hz
General
Switches:
Mode: Stereo / Mono
Tape
Monitor: Source / Playback
Selector: Phono-1 / Phono-2 / Tuner / Aux
Speaker
Switch 1 and 2: On / Off
Semiconductors: 23 Transistors; 2 Diodes
Power
Requirements: 100, 117, 220, 240 V 50/60 Hz
Power
Consumption: 130 watts Max.
Dimensions
(H x W x D): 135 x 395 x 278 mm (5⅜
" x 15⅜ x 10⅞") excluding rubber stand and knob
Weight: 8 kg
(17,6 lbs) net