Specifications
INSTRUCTIONS
FOR
ASSEMBLY
AND
OPERATION OF
THE
DYNAKIT
SCA-3S
STEREO
CONTROL AMPLIFIER
The
SCA-35
is
a
high
quality
stereo preamplifier
and
amplifier combination which serves
as
a control
center
for
various program sources
such
as
phonograph,
tape
and
radio.
The
SCA-35
permits
selection of
the
program
source
desired, modification of
the
tonal characteristics of
the
sound
source,
and
change
of volume;
it
provides
output
con-
nections for loudspeakers
and
headphones.
The
connection of various types of program sources
is
made on
the
back
panel
through
the
several sockets pro-
vided.
The
shielded
audio
cable'S
and
plugs
supplied
with
the program source
equipment
are
used
for connection be-
tween these components.
There
are
screw terminals for
connection of loudspeakers to
the
unit.
The
upper
row of
inputs
and
outputs
is
used
for
the
left channel,
and
the
bot-
tom row for
the
right
channel.
FRONT PANEL CONTROLS
The
front
panel
controls
have
been designed to
make
thf:
operation of
the
SCA-35 simple
and
obvious while pro-
viding
suitable
flexibility. Although
it
is possible to enjoy
use of
the
SCA-35 using
only
the
power
and
selector
switches
and
the
volume control, knowledge of
the
function
of
the
other
switches
and
controls
can
provide increased
listening pleasure.
Each
of these will be described briefly.
.Jeledor
Switch
•
Rotation
of
the
selector switch
to
the
marked
positions
permits
use of
the
marked
input
source. After switching to
"phono"
for example,
start
the
record player,
and
its
signal
will
be
available to you.
The
stereo-mono switch
beneath
the selector switch
extends
its
utility.
For
stereo signal sources, leave the
switch
in
the
"stereo"
position.
When
a mono source is
being played,
the
"mono"
position of
the
switch brings
this
single channel signal
through
both
loudspeakers. When
playing monophonic recordings with a stereo cartridge,
the
"mono"
position eHminates
most
of
the
vertical noise com-
ponents
of the signal.
When
a stereo
FM
tuner
is
tuned
to
a monophonic station,
the
"mono"
position of
the
switch
frequently eliminates noise
and
distortion.
Volume
Control
Clockwise rotation of
the
volume control increases
the
level of
the
signal
through
both
loudspeakers:
The
normal
setting
of
the
control will
depend
on
the
efficiency of
the
loudspeakers
and
the size of
the
signals from
the
cartridges
and/or
tuners.
It
should be recognized
that
the
position of
the
control is
not
related to
the
power level
at
which music
is
played-you
may
have a wide range of settings to give
a specific
sound
level.
Adjustment
should be
made
to
the
loudness level desired
without
regard
to
the
position of
the
knob pointer.
If
the
tuner,
or
other
input
equipment, has
its
own level
setting
or
volume control, this should be
set
so
that
when
...
witching from one
input
to
another,
the
sound is close to
~e
same loudness.
..
Beneath
the
volume control is
the
loudness switch.
When
it
is
switched to
"loudness"
there
is additional bass intro-
duced
into
the music when
the
volume control is
at
the
mid-point
or
below.
At
high settings of
the
volume control,
the
loudness switch has no effect.
The
reason for this fea-
ture
is
that
the
human
ear
has decreased sensitivity to low
frequencies
at
low volume levels,
and
the
loudness switch
helps to correct for this.
It
will
add
a fullness to low level
music which
can
enhance
its
pleasure.
Balance
Control
The
balance control is used to equalize
the
signals
at
the
two loudspeakers, which helps
to
center
the
sound.
Turning
the
balance control to
the
left will diminish
the
sound
to
the right speaker,
thus
making the sound source move to
the
left.
Turning
to
the
right
will move
the
sound source
to
the
right.
Normally
the
balance control is centered when
it
is in
the
mid-point
(12
o'clock),
but
differences
in
program-
ming,
in
speaker
efficiencies,
in
room acoustics,
and
in
com-
ponent
tolerance
in
the
SCA-35
may
require a
setting
off
the
mid-point. Since
the
effects of
this
control
are
very
gradual
in
the
area
of rotation from 9 o'clock
to
3 o'clock,
offsetting
it
in
this
region does
not
indicate abnormality.
When
rotated
to
either
extreme, the balance control cuts
off one
speaker
completely.
This
can
be
used
if different
signals
appear
in
the two stereo channels
(such
as
the
reverse
track
of a mono
tape
machine),
and
the
two
are
not
wanted
simultaneously.
Tone
Controls
The
bass
and
treble controls
operate
in
similar fashion
with
the
treble control affecting high frequencies,
and
the
bass control
the
low frequencies.
Each
of these gives "flat"
response
without
frequency discrimination when
the
pointer
is
at
12 o'clock. Clockwise rotation provides boost,
and
counter-clockwise rotation gives
attenuation.
When
program
sources
are
harsh
or
strident, treble
atten-
uation will improve
the
sound.
If
there is boominess, bass
attenuation
should be used.
Some
thin sounding
material
can
benefit from bass boost.
These
controls should be
set
to
whatever position
sounds
best,
but
it
should be remembered
that
departures
from
"flat"
are
of a corrective
nature;
and
the
user
should
not
get
in
the
habit
of listening to a corrected
tonal characteristic.
Beneath
the
tone controls is
the
filter switch. When
this
is
in
the
"filter" position
it
gives a narrow
band
response,
attenuating
both
high
and
low frequencies simultaneously.
This
should be
used
with poor program material,
such
as
scratchy
records, excessive rumble, noisy radio broadcasts,
and
so on.
By
attenuating
at
both
ends
of
the
spectrum,
it
does
not
create
a shift
in
overall tonal balance.
It
can
be
used
in
Conjunction with
the
tone controls for
great
extremes of tonal correction.
Power
Switch
The
power switch has
the
obvious function of turning
the
SCA-35
on
and
off (along with
any
equipment
in
the
switched
outlet
on
the
back
panel).
Allow
about
15 seconds
for
warmup
after
turning
this
switch to
"power."
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