There
are
numerous
ways
to
demonstrate
this
problem,
but
the essential result
is
that
many
more
than
twelve
pitches
are
required
in an
octave for
there to be pure
or
"just"
intonation
of
all
notes
in all
key
signatures.
So
a
keyboard
with
only twelve
fixed
pitches
per
octave
must
somehow
always be out
of tune.
Responses
to
this
problem
fall into
two classes.
First, one can tune the most
important
intervals
in a
key
signature
pure,
relegating the
inevitable mistunings to
lesser-used
tones.
These
"just
intonations"
allow the
keyboard to be in good tune for
one
or two
key
signatures
but in
bad tune
for the rest.
This tends to
confine
the instrument
to
music
of
simple,
predictable
harmony.
The
second
response,
equal temperament,
equalizes
the mistuning
between all
twelve
notes
so
ail key
signatures are
equally usable.
This method
allows unlimited
modulation
and
transposition
between the
keys, as Bach celebrated
in The Well-Tempered
Clavier.
Although
twelve-tone equal
temperament has standardized
keyboard
tuning,
it has
enough
disadvantages for
interest in alternative schemes
to have persisted.
Equal
temperament
requires there exist
no pure
intervals (except octaves) anywhere
on
the
keyboard.
Besides being more
or less
always out of tune with
itself,
the
keyboard
creates
problems in
ensembles where
vocalists, string-and wind-instrumentalists
have
finer control of
their intonation.
Equal-tempered thirds and sevenths
have
stimulated
the greatest
number of complaints
among sensitive
ears.
It
cannot be
denied there are
musical advantages to just intonation, nor
that equal
temperament will
remain the standard for
keyboards. Programmable
intonation
allows
the
keyboardist to choose.
Some will never use the feature. Others
will
find it
a
revelation.
The following instructions describe how to first
create an
equal-tempered
Scale
program, then how to
edit it into other tunings,
and how
to quickly move
between
Patch and Scale Modes.
5-2
USE
To
distinguish it from Scale
Mode, the normal state
of the
Prophet—which
you
are
already
familiar
with—is referred to here as Patch Mode.
Each of
the
40
memory
locations
in
a
file can
hold either a
Patch program
or a Scale
program:
but not both. In
Scale Mode the twelve knobs
which control
the
LFO,
OSC B
and
the
two
envelope
generators are used as
chromatic pitch
adjusters.
(Labels
are included for
more easily
identifying
the knob functions,
as shown
in
Figure
5-0.)
The
programmed knob
settings
which
produce specific sounds in Patch
Mode
will produce
only arbitrary
tunings in
Scale
Mode. Conversely, knob settings
which establish
precise
intonation
in Scale Mode
will
produce
only "garbage"
sounds
in
Patch Mode.
For this reason,
programs
created in
each mode must
not be
confused.
For switching
between Scale and Patch Modes,
the Prophet
uses a switch combination:
hold an};^ PROGRAM
SELECT, then press TUNE. Normally,
one selects the currently-
active program.
Note
that this action cancels any
editing which
may have been done.
Therefore
you must use ai recorded
(unedited) program,
or
be
in MANUAL mode (in
which
case
pressing
anx
PROGRAM
SELECT
will switch
the Prophet to Scale Mode).
This
switch-combination
is
used to switch
in either
direction
between
Patch
and Scale
Modes.
CMIOOOD
2/82
5-2
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