Page 1 OPERATING INSTRUCTIONS SOLID

Page 1 OPERATING INSTRUCTIONS SOLID
 ESTERO
OPERATING INSTRUCTIONS
RT MC ODO
SOLID-STATE STEREQ CONTROL AMPLIFIER
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SANSUI ELECTRIC COMPANY LIMITED
SANSUI
SOLID-STATE
STEREO
CONTROL AMPLIFIER
AU-777
Thank you for selecting the Sansui AU-777 Solid State Stereo-
phonic Amplifier, an excellent choice that will become more ap-
parent after years of rich stereo listening.
Sansui is known throughout the world for the unsurpassed quality
of its audio equipment line, be it a pre-main amplifier, a multiplex
stereo receiver, a speaker system, a turntable or a stereo head-
phone set, and takes the greatest efforts to merit and maintain
this reputation. |
The AU-777 is no exception. Not a single detail has been
overlooked in bringing this unit to you in perfect operating condi-
tion.
This manual has been prepared to aid you in keeping the AU-
777 working perfectly. Please read the contents of this manual
carefully before installing or operating the amplifier.
You will then be able to enjoy the world’s highest standards of
sound reproduction to the fullest.
FEATURES «oie 6 3, 4
SPECIFICATIONS/CHARACTERISTICS .......... о, 6
SWITCHES AND CONTROLS. .................. ee 7, 8, 9, 10
OPERATIONS В
LOUDSPEAKERS/RECORD PLAYERS........ 11, 12
TAPE RECORDERS, DECKS/TUNERS........ 13, 14
OTHER EQUIPMENTS ................ 0... ..... 15, 16
MAINTENANCE... en nee NE 17, 18
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SEPP ITL Circuitry
Single-ended input transformerless circuitry assures
70 watts music power, 30/30 watts RMS power and
25 watts X 2 RMS stereo power with the lowest
possible distortion. Over the entire frequency range,
20 to 50,000 Hz, the distortion never exceeds 0.5%
even at 100 milliwatts. The AU-777 overcomes
the problem of the solid-state amplifier in which
the distortion tends to be somewhat higher at low
power levels.
Negative Feedback Amplifier Stages
The negative feedback amplifiers used in all stages
from the first to the final offer appreciable improve-
ments in frequency response, signal-to-noise ratio
and distortion. The main amplifier has the frequen-
cy response of 20 to 100,000 Hz +1db. The pre-
amplifier output has a distortion factor of less 0.1%
at the rated output voltage of 1 volt.
Widest Possible Power Bandwidth
The AU-777 adopts a C.E. dividing system in which
quality silicon transistors are used in the phase
reversing circuit, assuring an outstanding frequency
response of 20 to 50,000 Hz with only 0.5% in
distortion.
Double Protective Devices 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-
777 is equipped with quick-acting fuses which pro-
tect the power transistors in case of overloads. The
new silicon transistors used have a very high per-
missible temperature range.
Dual-Concentric 2-Stage Negative-
Feedback Tone Controls
The dual-concentric 2-stage negative-feedback tone
controls provide independent adjustment of each
channel for boost and attenuations of 15 db at both
the bass and treble ends. The AU-777 operates fla
when the controls are in O position.
Two Phono Inputs
The AU-777 is provided with two PHONO inputs:
PHONO 1 and 2 have the input impedance of
ATK © and 100K Q respectively. Either can be used
depending on preference. In general, a cartridge
connected to 47K Q produces soft and mild tones.
If connected to 100K Q, it delivers tones accented
at high frequencies.
———.
Four Outputs and Seven Inputs
The AU-777 is equipped with all the necessary
outputs and inputs for an amplifier: pre-amp. output,
tape recording output and two center-channel out-
puts; two PHONO inputs, tape-head input and four
other inputs.
Two Center-Channel Outputs
The AU-777 is equipped with two terminals for
connection to a third amplifier. One is a flat output
and other is a 200 Hz high-cut output. You can,
just by connecting a monophonic amplifier, enjoy a
three dimensional effect.
Independent Pre-and Main-Ampli-
fier
The pre-and main-amplifier sections are designed
to be used independently, so that the AU-777 serves
as a top-quality channel amplifier. When not in
separate use, they are connected with PM connec-
tors.
Highly Effective Heat Sinkers
Thick (3 mm) aluminum heat sinkers keep the
power transistors running cool. The AU-777 oper-
ates free of trouble even if used continuously over
long periods of time.
Refined Front Panel
The front panel is functionally designed for easier
operation, and beautifully crafted to enhance the
beauty of your listening room. Walnut case option-
al.
Full Control Complement
The full control complement includes: 1. Tape
equalizer which can be switched to 19 cm/sec or 9.5
cm/sec depending on the tape speed; 2. Highly ef-
fective CR feedback LOW and HIGH FILTERS;
3. LOUDNESS control which compensates for the
loss of bass and treble at low listening levels; 4.
PRESENCE switch which enables you to enjoy a
double bass effect; 5. TAPE MONITOR switch
which compares the recorded tape with the program
source; 6. HEAD-PHONES jack for private liste-
ning; 7. MUTING switch for suppression the entire
sound range by 20 db; 8. SPEAKER SELECTOR
switch for a choice of speaker system; 9. Tape
recording output. |
MUSIC POWER
INPUT: AUX
:80
FREQUENCY:
DISTORTION (%)
POWER (W)
POWER OUTPUT HARMONIC DISTORTION
INPUT AUX
OUTPUT :8 0
— 1,000Hz
ec 20H72
—.— 20,000 Hz
a
DISTORTION (%)
POWER (W)
IM DISTORTION
INPUT _ : AUX
OUTPUT :80
FREQUENCY:
60Hz+-7KHz
POWER (W)
POWER BANDWIDTH
INPUT AUX
OUTPUT: BO
0dB : 30W 0.5%
—
RESPONSE (dB)
|
(Hz)
DAMPING FACTOR
OUTPUT: 80
MAIN AMPLIFIER SECTION
POWER OUTPUT (AT 8Q LOAD)
MUSIC POWER (IHF):
70W +1db total
CONTINUOUS POWER (LEFT/RIGHT)
CONTINUOUS POWER (BOTH CHANNEL DRIVEN):
HARMONIC DISTORTION:
30W/30W +1db
25W x2 +1db
less than 0.5%
POWER BANDWIDTH (IHF): 20~50,000 Hz
IM DISTORTION (60 Hz: 7,000 Hz=4 : 1):
FREQUENCY RESPONSE;
HUM AND NOISE (IHF):
OUTPUT IMPEDANCE:
DAMPING FACTOR:
PRESENSE SWITCH:
INPUT IMPEDANCE:
PRE-AMPLIFIER SECTION
OUTPUT VOLTAGE
0.8%
20— 100,000 Hz +1db
at normal listening level
100 db at rated output
8— 1602
24 (at 80 load)
50 Hz + 6 db
300 КО,
MAXIMUM OUTPUT VOLTAGE: 5V
RATED OUTPUT VOLTAGE: 1V (1800)
HARMONIC DISTORTION;
FREQUENCY RESPONSE:
HAM AND NOISE (IHF)
0.1% or below, at rated
output voltage
20~70,000 Hz + 0.5db,
—1.5db
PHONO 1, 2: 85 db at max. output voltage
TAPE HEAD: 80 db at max. output voltage
AUX 1, 2: 85 db at max. output voltage
INPUT SENSITIVITY(FOR RATED OUTPUT VOLTAGE)
PHONO 1: 2mV (47 KQ)
PHONO 2: 2 mV (100 KO)
TAPE HEAD 19: 1.5 mV (200 KQ)
ТАРЕ НЕАР 9.5: 1.3 т\ (200 КО)
AUX 1: 140 mV (100 K{2)
AUX 2: 140 mV (100 K2)
TAPE MONITOR: 140 mV (100K2)
RECORDING OUTPUT: 140 mV
CENTER-CHANNEL OUTPUT:
9.5V at 1,000 Hz (flat output)
9.5V at 20 Hz (low frequency output, fo=200 Hz)
CONTROLS AND SWITCHES
BASS CONTROL: 20 Hz +15 db (3 db step)
TREBLE CONTROL: 20,000 Hz +15 db (3 db step)
LOUDNESS CONTROL: 50 Hz +8 db, 10,000 Hz +5 db
(volume control at — 30 db)
LOW FILTER: 20 Hz —21 db
HIGH FILTER: 20,000 Hz —22 db
MUTING SWITCH: — 20 db (20—20,000 Hz)
MODE SWITCH: 1. STEREO NORM 2. STEREO
REV 3. MONO-L 4. MONO-R
SPEAKER SWITCH: 1. A 2.B 3. A+B 4. OFF
FUNCTION SWITCH: 1. TAPE HD 19 2. TAPE HD 9.5
3. PHONO 1 4. PHONO 2
5. AUX 1 6. AUX 2
OTHER SPECIAL FEATURES
Direct tape monitor. Headphone jack. Center-channel
output for connection to third amplifier. Muting switch.
Independent use of both main and pre-amplifier.
Protector indicator.
TRANSISTORS AND DIODES
TR: 25SC650 x 4, 25C281 x 10, 25C283 x 2, 2SD1 44 x 2,
25D143 x 4, 25D46 x 4
D; _SA-3Z x 4, SW-0502 x 2, QA91 x 2,
D-22A x 4 (Thermister), 2SF-656 x 1 (SCR)
POWER REQUIREMENTS
POWER VOLTAGE: 100, 117, 220 and 240V. 50 or 60 Hz
POWER CONSUMPTION: 165 VA. max.
DIMENSIONS
WIDTH: 1714”
HEIGHT (Excluding rubber stands): 614”
DEPTH (Excluding knobs): 134”
WEIGHT: 27.1 lbs.
* All rights reserve specifications subject to change without notice.
RESPONSE (dB)
TONE CONTROL
INPUT AUX
OUTPUT : 810}
(Hz)
RESPONSE
LOW, “HIGH CUT FILTER
INPUT AUX
OUTPUT:8N
FREQUENCY (Hz)
Power Switch
The amplifier is on when the POWER switch
lever is moved to the ON position. On the rear
panel of the amplifier there are two A.C. outlets.
The power to the left outlet marked SWITCHED
is controlled by the POWER switch.
Power Indicator —
The POWER indicator is lit when the POWER
switch is turned ON. It remains lit while the
unit 1s on.
Speaker Selector Switch
Chooses between one set of speakers A, and
another set B, which may be installed in the same
room or remotely in another part of your home.
It also has a position for running all speakers at
once (A+B), and another that cuts them all out
for private listening with headphones (OFF).
> Volume Control
The VOLUME control adjusts the over-all sound
level of both channels. Turn it clockwise, and
the volume is increased; turn it counterclockwise,
and the volume is decreased.
- Tape Monitor Switch
Enables you to compare a recorded tape with the
original program. When this switch is in the
PLAY BACK position, the recorded tape is heard
from the speakers. Monitoring is only possible
with a 3-head tape recorder.
NOTE: When you play back through the ampli-
fier, the TAPE MONITOR switch should be in
the PLAY BACK position as well. When not
needed, make sure the switch is in the SOURCE
position.
Function Selector Switch
This switch selects from among the various
program sources connected to the input jacks on
the rear panel of the amplifier.
1. Tape HD 19—Selects a tape deck with tape
speed of 19 cm/sec.
2. Tape HD 9.5—Selects a tape deck with tape
speed of 9.5 cm/sec.
3. Phono 1—Selects a record player connected
to the PHONO 1 inputs on the rear panel.
4. Phono 2—Selects a record player connected
to the PHONO 2 inputs on the rear panel.
5. AUX 1—Selects a tuner or other sources
connected to the AUX 1 inputs on the rear panel.
6. AUX 2—Selects a tuner or FM-MPX adaptor
connected to the AUX 2 inputs on the rear panel.
Mode Switches
1. Stereo— The Mode switches in the STEREO
NORMAL and STEREO positions connect the
left input to the left speaker and the right input
to the right speaker. This is the normal stereo
position.
2. Reverse—The left MODE switch in the
STEREO REVERSE position connects the left
input to the right speaker and the right input to
the left speaker.
3. Mono Right—The MODE switches in the
MONO RIGHT and MONO positions connect
the right input to both speakers.
4. Mono Left—the MODE switches in the
MONO LEFT and MONO positions connect the
left input to both speakers.
Protector Indicator —=
The protector circuit prevents damage to power
transistors. As soon as the circuit is activated,
the indicator lamp lights up to indicate trouble.
In this case, immediately turn the POWER switch
off and remedy.
Treble Controls
— == —
The LEFT and RIGHT TREBLE controls deter-
‘mine the amount of treble tones in the left and
right channels respectively.
With the TREBLE control in mid-position
marked 0, the treble tones will sound exactly as
they appear in the program source. If you wish
to emphasize the treble, simply turn the TREBLE
control clockwise. To decrease the treble loud-
ness, turn the TREBLE control counterclockwise.
The TREBLE control is graduated by 3db per step.
Bass Controls —=
The LEFT and RIGHT BASS controls determine
the amount of bass tones in the left and right
channels respectively.
With the BASS control in mid-position marked
0, the bass tones will sound exactly as recorded
or broadcast. If you wish to emphasize the bass,
simply turn the BASS control clockwise. To
decrease the bass loudness, turn the BASS control
counterclockwise. The BASS control is graduated
by 3 db per step.
Presence Switch —=
When the BASS controls are used for sound
compensation at low frequencies, they affect the
mid-frequencies as well, creating a boomy, rather
than flat sound. The PRESENCE switch is used
to improve the speaker damping at less than 125
Hz and to help reproduce crisp lows effectively.
Head Phones Jack —
Plug in a headset for private listening or monitor-
ing. The HEAD PHONES jack will accept any
standard stereo phono plug but a dynamic head-
set is recommended.
Low Filter —
Turntable rumble and other low-frequency noises
are reduced by setting the LOW FILTER switch
to the ON position.
High Filter —
Surface noise from old or worn records, tape hiss
and other high-frequency noises are reduced by
setting the HIGH FILTER switch to the ON
position.
—- 7
Muting Switch —
The MUTING switch attenuates music by 20 db
over the whole frequency range. It is used to
eliminate interstation tuning noise, to suppress
the back-ground noise heard when changing a
record, and to reduce the over-all sound level
temporarily while playing a record and others.
Balance Control —
This control adjusts for equal sound from both
left and right channels to compensate for slight
imperfections in program material, variations in
speaker output, and the vagaries of room acous-
tics.
— 10 —
Ï
Loudness Control
Whenever the volume is decreased to a low lis-
tening level, the music will seem to lose much ot
its bass and some of its treble. This effect is due
to the sensitivity of human hearing. When the
LOUDNESS switch is on, it provides the correct
amount of bass and treble boost required to com-
pensate for this change.
Connecting Loudspeakers
Any speakers of 8 to 16-ohm impedance can be
used with this amplifier. If you wish to connect ex-
tension speakers in other rooms of your home in
addition to the main set of speakers in your listen-
ing room, you can connect such speakers to the B
SYSTEM terminals of each channel. The speaker
selector switch on the front panel of the amplifier
enables you to choose between the A and B speaker
systems. It also has a position for running all
speakers at once, and another that cuts them all out
for private listening with headphones.
To connect speakers to the amplifier, proceed as
follows:
1. Connect the left speaker to the LEFT A (or B)
SYSTEM speaker terminals on the rear of the
amplifier. The lead from the speaker terminal
marked + should be connected to the correspond-
ing terminal screw marked + on the rear panel of
the amplifier, and the lead from the speaker termi-
nal marked — to the terminal screw marked — on
the amplifier.
2. The right speaker connections are made at the
RIGHT A (or B) SYSTEM terminals on the rear
panel of the amplifier in the manner described
above.
NOTES:
1. After connecting, determine whether the right
and left speakers are properly phased. Incorrect
phasing results from one channel pushing while the
other pulls, causing sound cancellation at some fre-
quencies or in some listening position. To correct,
reverse the phase (4 and —) of one of the two
speakers. (see “Phasing”—P. 18)
2. When connecting the speakers to the amplifier,
be careful not to make a short-circuit in the termi-
nals. All wire ends should be completely secured
by the terminal screws.
Connecting Record Players
The AU-777 has two sets of PHONO inputs to
accommodate a pair of players or pickup arms. The
inputs 1 and 2 have the input impedance of 47 and
100 KQ respectively, creating different tone colors
from each other. Use them according to your taste
and preference (See “Phono Inputs”)
To connect a record player to the amplifier, proceed
as follows:
1. Stereo record player —Connect the left channel
output of the record player to the LEFT channel
PHONO 1 (or PHONO 2) input jack on the rear
of the amplifier, and the right channel output of the
record player to the RIGHT channel PHONO 1 (or
PHONO 2) input jack on the rear of the amplifier.
2. Monophonic record player—Connect the output
of the record player to the left or right channel
PHONO 1 (or PHONO 2) input jack on the rear of
the amplifier.
Listening to a Stereo
(or Monophonic) Record
1. Set the FUNCTION selector switch to PHONO
1 or PHONO 2 depending on the input jacks to
which a record player is connected.
2. Set the MODE switches to STEREO or MONO
depending on whether the record player is stereo
or monophonic.
3. Switch on the record player and adjust its speed
of rotation (RPM) to the record.
4. Set the needle down on the record.
5. Adjust the BALANCE control for equal sound
from both left and right channels.
6. Adjust other front panel controls and switches
to your taste and room acoustics.
— 11 —
NOTES:
1. If you play a monophonic record on a stereo re-
cord player, it is recommended to follow the same
procedure as for a stereo record to obtain better
results.
2. To adjust the BALANCE control for equal
other player or cartridge
sound from both channels, proceed as follows:
a. Play a monophonic record on a stereo record
player through the amplifier with the MODE
switches in the STEREO position.
b. Step back and listen. Proper balance exists when
the sound seems to originate at a point midway
between the speaker systems.
3. For your convenience, insert the line cord plug
of the record player into the outlet marked
SWITCHED -© b- on the rear of the amplifier.
SYSTEM: A
RIGHT SPEAKER
—— 12 ..—.
LEFT SPEAKER
SYSTEM - B
LEFT SPEAKER RIGHT SPEAKER
Connecting Tape Recorder and
Tape Deck
The AU-777 accomodates both tape recorders
and tape decks for recording and playback func-
tions. If the tape recorder used has three heads
(separate heads for playback and recording), moni-
toring is also possible.
Recording
For a stereo tape recorder, connect its left channel
Input to the LEFT channel TAPE REC terminal
on the rear of the amplifier, and its right channel
input to the RIGHT channel TAPE REC terminal.
For a monophonic unit, connect its recording input
to either TAPE REC terminals.
1. Set the FUNCTION selector switch to PHONO
1, PHONO 2, AUX 1 or AUX 2 as appropriate.
2. Set the MODE switches to STEREO or MONO
depending on whether the recording is stereo or
monophonic.
3. Set the tape recorder for recording.
4. Adjust the amplifier’s front panel controls and
switches according to taste and/or listening condi-
tions.
Playback
For a stereo tape recorder, connect its left channel
output to the LEFT channel TAPE MON terminal
on the rear of the amplifier, and its right channel
- output to the RIGHT channel TAPE MON termi-
nal. For a monophonic unit, connect its output to
either TAPE MON terminals. For a stereo play-
back deck, connect its left channel output to the
LEFT channel TAPE HEAD terminal on the rear
of the amplifier, and its right channel output to the
RIGHT channel TAPE HEAD terminal. For a
monophonic unit, connect its output to either
TAPE HEAD terminals.
1. For use with tape deck, set the FUNCTION
selector switch to TAPE HD 19 or TAPE HD 9.5
depending on the tape speed: 19 cm/sec or 9.5 cm/
sec. For use with a tape recorder, turn the TAPE
MONITOR switch to the PLAYBACK position.
2. Set the MODE switch to STEREO or MONO
depending on whether the playback is stereo or
monophonic.
3. Set the tape recorder or tape deck for playback.
4. Adjust the amplifier’s front panel controls and
switches according to taste and room acoustics.
Monitoring
To monitor a tape with a 3-head tape recorder,
connect its recording inputs to the LEFT and
RIGHT TAPE REC terminals on the rear of the
amplifier, and its outputs to the LEFT and RIGHT
TAPE MON terminals. For a monophonic unit,
connect to either terminal of LEFT and RIGHT
channels.
The procedure for monitoring with a 3-head tape
recorder is the same as for playback.
NOTES:
1. The recorded tape cannot be controlled by the
controls and switches on the front panel of the
amplifier. They control the sound from the speak-
ers only. To obtain better recording results, record
the tape directly through the amplifier, not through
a microphone placed in front of the speakers.
2. Before connecting and operating the tape re-
corder, be sure to look up the manufacturer’s oper-
ating instructions.
3. The TAPE MON switch must be in the
SOURCE position except when the tape is being
monitored or played back by the tape recorder.
4. The outputs of a tape recorder or tape player
having a playback pre-amplifier should be con-
nected to the TAPE MON input jacks on the rear
— 13 —
of the amplifier. In this case, the TAPE MONI-
TOR switch should be in the PLAYBACK posi-
tion.
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Connecting Tuners
For a stereo tuner, connect its left channel output
to the LEFT channel AUX 1 (or AUX 2) input
jack, and its right channel output to the RIGHT
channel AUX 1 (or AUX 2) input jack. For a
monophonic tuner, connect its output to either
jack.
For use with an FM-MPX adaptor, connect the
tuner output to the adaptor input; then connect the
left channel output of the adaptor to the LEFT
channel AUX 2 input jack, and the right channel
output to the RIGHT channel AUX 2 input jack.
NOTE: Before connecting and operating the tuner
and FM-MPX adaptor, be sure to look up the
manufacturer’s operating instructions.
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AC outlets for tuner or record -———
player etc.
14 —
Listening to a Stereo FM Program
1. Set the FUNCTION selector switch to AUX 1
or AUX 2 depending on the input jacks to which a
stereo tuner is connected.
2. Set the MODE switches to STEREO.
3. Select the desired station with the tuner.
4. Adjust the amplifier’s front panel controls and
switches according to taste and room acoustics.
Listening to a Monophonic
Program
1. Set the FUNCTION selector switch to AUX 1
or AUX 2 depending on the input jacks to which a
monophonic tuner is connected.
2. Set the MODE switches to MONO.
3. Select the desired station with the tuner.
4. Adjust the amplifier’s front panel controls and
switches according to taste and listening conditions.
Listening to a Stereo FM Program
with a FM-MPX Adaptor
1. Set the FUNCTION selector switch to AUX 1
or AUX 2 depending on the input jacks to which a
tuner and a FM-MPX adaptor are connected.
2. Set the MODE switches to STEREO.
3. Select the desired station with the tuner.
4. Set the FM-MPX adaptor to STEREO.
5. Adjust the amplifier's front panel controls and
switches according to taste and room acoustics.
Separate Pre-AMP and Main-AMP
Circuits
The AU-777 is provided with a pre-amp output
circuit which picks up the output of the pre-ampli-
fier alone, and with a main-amp input circuit which
drives the main amplifier alone.
To connect additional pre- and main-amplifiers:
1. Remove the PM connector from the jacks
marked PRE OUTPUT and MAIN INPUT.
2. The input of an additional main amplifier should
be connected to the PRE OUTPUT jacks. The
output of an additional pre-amplifier should be con-
nected to the MAIN INPUT jacks.
NOTE: The connection of the additional pre-amp-
lifier to the MAIN INPUT cuts off all the front
panel switches and controls except the PRESENCE
and SPEAKER SELECTOR switches. Thus, to
adjust the tone and volume, operate the controls of
the additional pre-amplifier. When connecting the
additional main amplifier to the PRE OUTPUT,
the tone and volume can be adjusted by the controls
of the AU-777.
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Multichannel Stereo
The AU-777’s separate pre-amp and main-amp
circuits enable you to arrange a multichannel ste-
reo system. In this system, each frequency band is
divided on the input side, rather than the output
side of the amplifier; woofers, mid-ranges and
tweeters have their own amplifier as illustrated
below.
The multichannel stereo arrangement is said to be
the best hi-fi sound reproduction method available,
featuring the following advantages:
1. Since the tweeters, mid-ranges and woofers have
their own amplifier, any speakers can be used for
stereo arrangement.
2. You can obtain better filter characteristics than
the conventional LC crossover network. The op-
timum crossover points can be determined for the
highest performance and efficiency of the speakers.
3. Since there is no component between the ampli-
fier and speaker, the damping factor of the amplifier
is not affected and it is directly coupled to the
speaker.
4. You can select the best amplifier available for
each of the tweeters, mid-ranges and woofers.
— 16 —
Three-Channel Stereo
In the three-channel stereo arrangement, one woofer
is connected to the center channel and a tweeter/
mid-range speaker system is connected to the right
and left channels. This idea is based on the fact
human ears are not sensitive to the direction of bass
tones of less than 200~300 Hz. The advantage is
that only one woofer is enough for this stereo sys-
tem and that the lows are reproduced more effec-
tively.
The AU-777 is provided with output terminals for
center-channel amplifiers. If you wish to connect a
center-channel speaker for the three-channel stereo
arrangement, connect an amplifier for the low-fre-
quency speaker to the HIGH CUT terminal (the
frequencies of more than 200 Hz are cut off in the
filter circuit of the AU-777); and then connect the
third speaker to the center-channel amplifier.
Another method is to connect a monophonic power
amplifier to the L + R OUTPUT FLAT terminal,
and the third speaker to the amplifier. In this case,
the mixed sound from the right and left channels
does not pass through the filter circuit.
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Protector Indicator
The AU-777 has a special protector circuit,
which, combined with an SCR circuit and quick-
acting fuses, protects the silicon power transistors
from damage if a chance overload occurs. As soon
as this circuit is activated, the Protector Indicator
will light up and the amplifier’s sound level will be
markedly reduced.
As soon as this Indicator lights up, push the
POWER switch off and find and eliminate the
source of trouble.
IMPORTANT: The Indicator lamp might light up
due to instantaneous overcurrent, rather than be-
cause of an internal defect. In this case, push the
POWER switch off for about five seconds, then
push it on again. If the lamp is illuminated this
time, push the POWER switch off immediately and
find and eliminate the source of trouble.
Probable cause: a shorted output circuit.
Connections
Always check to see that leads are connected firmly
and properly to their corresponding output or input
terminals. If the connections are loose or in touch
with other parts, the AU-777 will not perform
normally, and may produce undesireable noise. If
used in such a way tor a long time, it will eventually
break down. Always read the manufacturer's in-
structions for tape recorder, record player, tape
deck, etc. before connecting.
Hum and Howling
If, when using a tape recorder or record player,
unpleasant humming or howling is heard, it 1s
usually a result of the following:
The record player is placed on or near the speaker
box causing sound waves to be transmitted from
the speaker to the player (howling). To prevent
this, place the record player away from the speaker
box or put a thick cushion between the two com-
ponents.
A low buzzing sound will also be produced if ade-
quately thick shieldwire is not used for connections,
or if connections have not been properly made. Be
sure that the shieldwire is properly soldered to the
pin-plugs as illustrated in “Connecting Wire”, and
that the motor and pickup arm or the record player
are properly grounded.
Power Fuse
If the unit remains completely dead when the power
is switched on (POWER indicator fails to light), the
power fuse is probably blown. In this case, remove
the power plug from its AC outlet and replace the
fuse after finding and eliminating the trouble that
caused the fuse to blow. (Consult the Troubleshoot-
ing Section in your Service Manual)
Use only a glass-tubed 2-ampere fuse. Never at-
tempt to use a piece of wire or a fuse of a different
capacity as a substitute.
Quick-Acting Fuses
If the power indicator lights up but the set does not
play, it may be the result of a blown quick-acting
fuse in the power circuit of the power amplifier.
To replace, remove the power plug from its AC
outlet. Then remove the bonnet from the AU-
777 and check for the blown fuse. Before replacing,
check for the source of trouble that has caused the
fuse to blow. (See your Service Manual)
Never use a fuse with a different capacity. The
correct capacity is 2 amperes.
If the new fuse blows as soon as the POWER
switch is pushed on, check for the defective power
circuit. If the trouble source cannot be located,
contact the nearest Sansui dealer or Service Center.
Connecting Wire
Be sure to use adequately thick shieldwire when
connecting a tape recorder, tape deck, record player
or other components to the AU-777. The use
of an ordinary twin leadwire may cause hum or
noise. Don't use shieldwire longer than 7 feet (2
meters). The use of a longer wire leads to greater
attenuation at high frequencies.
Phasing
The right and left speakers must be properly phased
so that the two channels push the sound waves out
together. If one pushes while the other pulls, there
is sound cancellation at some frequencies or in some
listening locations. Incorrect phasing is caused by
improper speaker connections and is evidenced by
a loss of bass when a monophonic record is listen-
ed to on a stereo player at a point halfway between
the two speaker systems. If incorrect, reverse the
speaker connections of either speaker.
Voltage Selector Plug
The AU-777 can be used in four different voltage:
100V, 117V, 220V and 240V. The voltage selector
plug is in the 117V position. To change, remove
the plug marked an arrow; direct the arrow head
to the voltage in the area you live; and insert
the plug firmly. Be careful not ot plug into the
wrong jack.
AC Outlets
The AU-777 is provided with two AC outlets on
its back panel. One outlet (marked —© © ) is
switched on and off by the POWER switch on the
front panel.
Caution: The maximum capacity of this outlet is
50 VA, and the other (marked —0-0-) is 100VA.
Never use either beyond their rated capacity.
—— 18 —
Sansui
ECT осо оо завеса она оо аа
SANSUI ELECTRIC COMPANY LIMITED
Head Office; 14-1, 2-chome, Izumi, Suginami-ku, Tokyo, Japan. TEL. 323-1111
Printed in Japan (29010M6)
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