Sansui AU-70 - Amplifier Features

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
the wh ole 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 r monic 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
su ch clarity .
- 3
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-
tions.
Your AU-70 uses a three - stage amplifier
circuit
in its interm ediate 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 SIN 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 equ ipped
with tone defeat which cancels 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
can
get an accurate, perfectly flat response from
your AU-70 just by flipping a switch.
BLEND CIRCU IT PERMIT CONTINUOUS
S HIFT FROM MONAURAL . TO STEREO
As you turn the "BLEND" switch clockwise,
y
our AU -70 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, particularly
s
tron g effect of th e conce rt ha lL
EA S Y- TO- READ THREE - RAN GE OUT P UT
L EV EL METERS
Each output level meter can be switched over to
any of
the three scales of 5, 10 and 25 watts.
The meters not only give direct readings of both
ch anne ls, but also indicate any lack of balance
between the right and left outputs. These prove
very useful
in balancing the outputs .
THREE - DIMEN S IONAL P ERFORMANCE
POSSIBLE WITH CENTER - CHANNEL
OUTPUT TERMINAL
Y~ur AU -70 ha s an ou tput terminal for the
center -channel amplifier. Connect it to your
monaural amplifier to produce a three-dimensional
effect.
EQUIPPED WITH ADVANCED , HIGH-
PERFORMANCE ACCESSORY CIRCUITS
Your AU -70 is equipped with various advan ced
access
ory circuits such as loudness control, low
an d high filters, tape monitor, tone defeat, pre-
sence, blend, speaker switch and headphone jack.
- 4 -