Yamaha DX11 Operating Manual page 30

DATA
COMPATIBILITY
WHAT'S
FM?
The
DXU
uses the
same
4-operator, 8-algorithm
FM
syn-
thesis as the
TX8tZ, DX21, DX27,
DX27Sand
DXlOO, and
voice data can be transmitted
and
received
between them.
However,
there are a
number
of
diffrences.
*
The Frequency
CRS( RATIO)
adjustment
(p.
10) is
equivalent
to the
values
programmable
in
the
DX21/27/27S/100.
The
FIN(RATIO)
adjustment
is
ad-
ditional precision available in the
DX
1
1
and
TX8
1
Z. Also,
the
DX21/27/27S/100 operators have no
FIX mode.
*
The DX21/27/27S/
100 operators
produce
only sinewaves.
When
a
DXII
voice that uses
non-sinewave operators
(pTO)
is
loaded
into a
DX21/27/27S/100,
it
will
not
sound
the
same.
*
EG
RR. The
Envelope Generator
Release
Rate on
the
DX21/27/27S/100
can be
set to
0,
whereas
the
DXU
and
TX81Z EG-RR
minimum
setting
is 1.
When
voice data
is
received
from
a
DX21/27/27S/100, any
EG
release rates
of are
set to
I
.
*
EG-EG
Shift
is
not a parameter on
the
DX2
1
/27/27S/
1
00,
and
will
be ignored
by them.
* Parameters
that the
DXU
does
not
have (chorus)
will
be
set to
Off
or
0.
*
The
DXll BC
Pitch Bias of
-50
to
+50
(p.
13)
corre-
sponds
to the
DX27/100
BC
Pitch Bias of
99.
However,
the
curve
is
different.
(Exponential, not
linear.)
* The
TX8IZ
has
no
PEG
or Aftertouch parameters.
*
The
TX81Z
has only
one
setting for
each of the three
effects.
A
complete discussion of
FM
Synthesis
is
beyond
the scope
of
this
manual.
Here
we
will
cover the basic ideas of
FM,
and
briefly explain
some
of the
DXl
1
voice parameters.
For
a
more
detailed study, see
"FM
Theory
&
Applications:
By
Musicians
for
Musicians", by Dr.
John
Chowning and David
Bristow, published 1986 by
Yamaha
Music Foundation.
Other
booklets covering various aspects of electronic
music
are also available
from
Yamaha.
FREQUENCY
MODULATION
FM
stands for
Frequency Modulation.
In
FM,
one
waveform
modulates another waveform,
creating
a
new,
complex
waveform,
as
shown
below. So, to
do
FM
synthesis,
we
need
two
oscillators.
The upper one
is
called the
"Modulator" and
the
lower one (which goes directly to the
output of the syn-
thesizer)
is
called
the
'^Carrier'".
The
complexity or
"brightness" of the resulting
waveform
will
depend on
the
output
level
of
the
Modulator.
Modulator
Output
Level
Rssulting
Sound
^
EG
(Envelope Generator)
By varying
the
output
level
of the
modulator,
we can produce
all
kinds of sounds.
However, sounds
in
the real
world usually
change
as
time goes
by.
This "shape
in
time"
is
called the
Envelope.
If
the
output
level
oi'
the
modulator changes, the
tone
will
change.
If
the
output
level
of
the carrier
changes,
the
volume
will
change.
—
J.
—
Kfv Of(
Key
On Key Off
28