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This amplifier has a maximum output of 50 watts (25W-25W)
and features
an amazingly lo w distortion factor of not more
than 0.15% at
20W. A high- quality amplifier with many exci
ting features, it
is delivered to you with Sansui's fullest confidence.
This booklet explains the steps necessary for operating and
caring for your new
the . AU-70 . Read an the instructions
carefully and retain for future use.
CONTENTS
FEATURES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3, 4
SPECIFICATIONS ..... ... .. ... ... . .. ... ... .. . ... ..... ........... . 5
CHARACTERISTICS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
CONNECTIONS.......................................... ...... .... 7, 8, 9, 10
SWITCHES AND CONTROLS ........ ...... .......... .... ...... 11, 12
OPERATIONS.... ................ .... .... .... ...................... 13, 14
HI NTS ON USE ................ ................ ................ .. 15, 16
SERVICE NOTE ................ .......... ...... ...... ............ 17, 18
PA R TS LIST ...... ...... ....... .... ......................... .... .. 19, 20, 21
SC H EMATIC DIAGRAM .......... ........ ... . .......... ....... . 22
PARTS LAyOUT ... ..... . ... ... . ............ ... .. ..... ....... ... .. . 23
SUI
STEREO CONTROL
AMPLIFIER
AU-70
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FEATURES
7189A P.P. PRODUCES 40W WITHOUT
PISTORTION (MAX . 0.95 % AT 30 CPS AND
·0.15 % AT 1,000 CPS )
The 7189A power tubes operate in class AB,P .P.
(fixed bias) Jor high-fidelity reproduction. Their
combined . maximum output is limited to 50 W.
The amplifier incorporates a multiplex feedback
circuit (total negative feedback: 26 dB) for the
first time in this class of amplifiers in Jilpan.
This makes it extremely low in distortion over
th e w hole frequency range. Total harmonic dis
tortion at 1 kc is 0.15%. At 30 cps, a very low
frequency at which it is extremely difficult · to
minimize ha rmonic distortion, the distortion is
limited to
not more than 0.95% . This is quite
a feat for a 50-watt amplifier. Another remarkable
feature is the damping factor of 18, a figure which
is lower than that of triode power tubes ' coupled
in P .P . This is why bass sounds come out with
such clarity .
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NFB USED IN ALL AMPLIFIER CIRCUITS ,
FROM PREAMP TO POWER AMPLIFIER
The low distortion of the power amplifier is
meaningless if the preamplifier generates distor
tion s.
Your AU-70 uses a three -stage amplifier
circuit
in its interm ed iat e or cpntrol amplifier
unlike conventional one-stage control amplifiers
and has all its circuits in a single negative -feed
back loop. These make your AU - 70 free from
noise
and distortion.
SUPER-PRECISION TRANSISTOR PREAMP
LIFIER ELIMINATES HUM AND NOISE
The exclusive Sansui four-transistor preamplifier,
which features a transistor circuit factor of 4-as
compared with conventional 5-1O-al1d a transistor
noise factor of 2
dB-as compared with conven
tional 5 dB, eliminates
hum and noise, the enemy
of high -fidelity reproduction. The amplifier has
a
much better S IN ratio and a gain three times
larger than vacuum-tube amplifiers.
EACH CHANNEL CAN BE OPERATED IN
DEPENDENTLY EQUIPPED WITH TONE
DEFEAT
Each channel has independent tone contro ls for
bass
and treble. This makes fine adjustment
possible. Moreover, each channel is eq u ipped
with tone defeat which cance ls the tone control
circuits.
You can easily obtain a flat frequency
response
without causing any undulation in
response
or redu ced gain in bass and treble as in
the case of conventional mechanical control by
means of a tone volume knob. Therefore, you
ca n
get an accurate, perfectly flat response from
your AU-70 just by flipping a switch.
BLEND CIRCU IT PERMIT CONTINUOUS
SHIFT FROM MONAURAL . TO STEREO
As you turn the "BLEND" sw itch clockwi se,
y
our AU - 7 0 gradually shifts from monaural to
stereop honic repr~duction. This feature enables
you to get full stereophonic effect by compensa
ting program sour ces which give a, particularl y
s
tron g effect of the conce rt ha lL
EA SY-T O - READ THREE -RAN GE OUT PUT
LEV EL METERS
Each output level meter can be switched ove r t o
a n y of
the three scale s of 5, 10 and 25 watts.
The meters not only give direct readings of both
ch anne ls , but a lso indicate any lack of balance
between the right and left outputs. These pro ve
ve ry useful
in balancing the outputs .
THREE -DIMEN SIONAL PERFORMANCE
POSSIBLE WITH CENTER -CHANNEL
OUTPUT TERMINAL
Y~ur AU -70 ha s an ou tput terminal for the
center -c h annel amplifier. Connect it to your
monaural amplifier to produ ce a three-dimensional
effect.
EQUIPPED WITH ADVANCED , HIGH
PERFORMANCE ACCESSORY CIRCUITS
Your AU -70 is equipped with various advan ce d
acc ess
ory c ir cuits such as loudness control, low
an d high filters, tape monitor, tone defeat, pre
sence, blend, spe ak er sw itch and headphone jack .
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