ARP 2600 - Troubleshooting Common Patch Issues

49
(If
you
don't, ask
yourself
as
systematic
a set of
questions
as
you
can
about the signal
path you just set
up
and about
what opera-
ting characteristics
you
have
set for each
function
in
the
path. In
the
course
of
answering
your
questions
you
will
discover that
you've
over-
looked
something. For the
present case
we suggest the
following.
1)
Is
VC03 in
its
audio range?
2)
Have you
by
accident pressed
one of
the
upper
keyboard notes
and driven
VC03
out
of
audible
range?
Remember
that the
keyboard will hold
for an
indefinite
period
of
time the
last
voltage keyed
from it; develop
the
habit
of
flicking the
lowest
key
before
setting
any VCO initial
frequency
controls
or
attempt-
ing to
tune
two or more VCO's to
any particular pitch
or
pitch inter-
val.
3)
Is
the VCF initial
frequency control
set
to maximum? Is
the
resonance
control
set to
minimum?
4)
Was
it really
the
input
from
VC03 to
the filter,
or
some
other one, that you opened? Was it
really
the filter
input to the
mixer that you
opened, or
some
other one?
5)
Is the
speaker
volume
high enough?
6}
Is the
power
on?
Is
the unit
plugged in?
If
such
a
check
procedure doesn't
reveal
anything
wrong,
and if
another one
still
doesn't show any
errors
in
setup,
and
there
still isn't
any sound,
your
2600 is
in
need
of
service.
Call
your
dealer
immediately.
If, on the
other hand,
you
discover
and rectify
dn error
in
the
patch or
in
your
control
settings,
you
will indeed
hear the
sound
of
VC03
pouring
from
the loudspeakers,
and
you're on
your
way. We
resume
our
narrative.)
This
sound
is the
VC03 sawtooth
waveform,
essentially unmod-
ified,
at a
frequency
somewhere below 1KH/.
Experiment
on it:
use the VC03
frequency
sliders to
raise
dnd lower
the
pitch.
You
will
discover that
the initial
frequency
slider
can raise dnd
lower
the
pitch
to
above and
below
audibility
without
assistance
from
the fine
tune
slider.
The
fine
tune slider can
only change
the pitch
by
about one octave, certainly
not
by more than
two. The
keyboard
control
voltage
"plays"
the
oscillator
as
though
it were
a
flute or
pcnny-whistlc-play a scale on the keyboard and
the keyboard
control
voltage will
play
a
scale
on
the
VCO. But using
a
control
vol-
tage
doesn't disconnect
the
manual oscillator
control,
not
at all: play
a keyboard
scale
with one
hand while
with
the
other
you
move
the
initial oscillator frequency
control.
Voltage-controlled
Oscillator
VC03L-^
VCF
h->out