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Signal Processing - Yamaha CS-80 Instruction Manual

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and
you
suspect
some
control(s)
was
accidentally
moved,
don't
panic;
just
go
to
a
preset
while
you
check
the panel
levers
and
switches.
TIPS
ON AUXILIARY
SIGNAL PROCESSING
Phasers,
echo
boxes,
reverbs,
digital
delay
lines,
parametric
equalizers,
fuzz boxes,
wah-wah
pedals,
graphic
equalizers,
etc.
are
all
auxiliary
signal
processing devices that
may
be
used with
a
synthesizer.
The
synthesizer
output
is
higher
in
level
than
most
electric guitar
pickups, but
it
can
still
be
plugged
into
many
guitar-type pedals
and
boxes
if
the
HIGH/LOW
switch
is
at
LOW
and
the
Volume
control
is
set at
a
moderate
level.
On
the
other hand,
it
may
be
better to use
an external
attenu-
ation
pad
to
match
the
level
of
the synthesizer out-
put
to
a
high-sensitivity
(low
level)
effects device.
Signal
processing
equipment
made
to interface
with
studio
equipment
can
usually be driven directly
from
the synthesizer
output
with the
HIGH/LOW
switch
in
HIGH
position.
In
all
cases
it is
a
good
idea
to
check
the
level
(sensitivity)
specifications for
the
auxiliary
signal
processing unit against the synthesizer
specifications.
Many
of
the
sounds
you
might
wish
to
achieve with
an
outboard
effects
device
can
actually be
achieved
with controls
and
circuits
that
are built into
the
synthesizer.
For example,
tremolo, vibrato
and wah-
wah
can
all
be
obtained
using the
sub
oscillator.
Where
practical,
use the
built-in
capability of
the synthesizer,
since the
sound
will
be
going
through fewer
circuits
and
will
therefore have the lowest noise
and
best
frequency
response.
Many
patches
are greatly
enhanced
by
auxiliary
signal
processing.
The
realism of
"acoustic "
instru-
ment
patches can
be very
much
heightened by
using
reverb.
The
synthesizer's External input
can
afford
some
interesting
effects.
To
obtain strange
''vocal"
effects,
plug
in a
source
of
a
very
pure,
high-frequency sound,
such
as
a
10kHz
or
higher
sine
wave
oscillator.*
Then
engage
the
VCF
(filter)
on
the
sub
oscillator,
and add
a
lot
of
Resonance
[8
and/or 27
&29]
.
The
External
input
is
not
made
for
use with
guitars or
microphones,
and even
if
a
preamplified
guitar or
mic
is
used, the
results
could
be disappointing.
Some
preamplified
(electric)
instrument outputs
will
produce
interesting
results
when
connected
to the External input.
*The
purer
the sine
wave
fed
to
the
externa/
input, the
better-sounding
the result
will be.
DIRECT
BOX
A
"direct-box"
is
a
type
of adapter.
In
some
cases,
rather
than
connect
the
CS-80
directly to
a
mixer,
one
could connect
the synthesizer
to
an
instrument
amp.
The
direct
box
would
then be used
to interface the
instrument
amplifier's
speaker output
(guitar
amp,
P.
A.
amp,
etc.)
with the
mic
or
line level
mixer
input,
thus
including the
amplifier's reverb,
tremolo,
brightness
and
other
effects
in
the
mix.
Another
application
for
a
direct
box
is
to achieve
grounding
isolation
between
an
unbalanced
line level
output and
a
balanced
mic
or
line
level
input.
The CS-80
output
has
a
low
source
impedance
so
that
it
will
drive
a
low impedance (600-ohm)
or high
impedance
input
without
adapters.
The CS-80 output
is
unbalanced,
meaning
that the
signal,
which
flows
through
a
single-conductor shielded
cable,
is
grounded
on one
side (the shield)
and
ungrounded on
the other
side (the
center
conductor). This
arrangement
is
per-
fectly suitable for cables
of
up
to 3
m
(10')
in
length.
When
a
longer distance separates the
CS-80 output
from
the
mixer
input,
it is
desirable to use
a
balanced
line
rather
than an
unbalanced
line
for better rejection
of potential
hum,
noise
and
interference.
In a
balanced
line,
the cable shield
is
grounded, but
carries
no audio
signal;
two
center conductors, neither of
which
is
grounded,
carry the
signal.
Provided
the
mixer
input
is
balanced (transformer
isolated),
a
balanced
line will
be
obtained by connecting
a
direct
box
at
the
CS-80
output.
if
two
or
more CS-80
outputs
are
connected
to
one
mixer,
it is
a
good
idea to use
a
direct
box on
each
output
so that the
ground
to
all
but
one
of
the inputs
can be interrupted
without
breaking
the
signal
path.
This avoids so
called
"ground
loops," multiple
grounding
circuits
between
the
mixer and
the
synthesizer that
might
otherwise introduce
hum.
PAD
IN/OUT
SWITCH
The
direct
box
illustrated
can be used
in
three
ways,
as
indicated below,
and
its
three switches
should
be
set
as
required.
The ground
switch breaks the
ground
(shield
connection)
in
the
XLR
output,
and
should
be
set
for
minimum
hum. The
Pad drops
the
signal
level
so
that high
level
outputs
do
not overdrive lower
level
mixer
inputs.
The
Filter,
which
only
works
when
the
Pad
is
switched
IN,
simulates the high
frequency
roil
off of
a
typical guitar
amp's
speaker. Since clipping
distortion
in a
guitar
amp
often creates high
frequency
harmonics,
the
filter
switch,
by lowering
high
frequency
response,
also cuts distortion.
47
Assemble
the unit
in
a
small
metal mini-box,
and
keep
the
phone
jacks isolated
from
the
chassis of the
box.
Also keep
the
box
away
from
the
chassis
of the
instrument
amplifier or
any
other
grounded
object.
if
you
chose
a
transformer other than
the
JE-DB-D,
it
should have
similar characteristics:
an
impedance
ratio
of
20k-ohms
(primary)
to
1
50-ohms
(secondary), dual
faraday
shields,
very
low
capacitance
on
the
primary
winding,
and
full
audio spectrum
response.
A
commercial
direct
box
may
be
purchased,
or
a
qualified
technician
can
build
one from
the
schematic
diagram
shown
here.
The
design,
courtesy
of
Deane
Jensen (Hollywood, CA),
is
included
in this
manual
for
the benefit
of
the synthesizer
user,
and
does not
represent an
endorsement
by
Yamaha
of the
specific
products mentioned. This
direct
box
also
works
well
with
electric guitars,
maintaining
good
high
frequency
response because the
pickup
is
not
loaded.
The JE-DB-D
transformer
is
available directly
from:
Jensen Transformers
1617
North
Fuller
Avenue
Hollywood,
CA
90046
(INSULATED BUSHING)
SWITCHCRAFTN-in
(FROM SYNTHESIZE R)[ir
(TO
INSTRUMENT AMPlQ^
INPUT/
BRIDGING
JACKS
+
+
V^
^S^
JENSENS
JE-DB-D
22uf
25V
22uf
25V
1.
T
il
FILTER
SWITCH
Direct
Box
Schematic
XLR-3-nC
ID3M)
2-i
(TO
p
MIXER)
OUTPUT
JACK
\
GND
SWITCH

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