Sequential Prophet T8 User manual

OPERATION MANUAL
~~ SEQUENTIAL
S55 cizcuic) inc

MODEL 1008
Manual No. CM1008B
PROPHET-T8 SYNTHESIZER
OPERATION MANUAL
By Stanley Jungleib
Sequential Circuits, Inc. Sequential Circuits, Inc.
Nijverheidsweg Llc 3051 North First Street
3641 RP Mijdrecht, Netherlands San Jose, California 95134-2093
02979-6211 408/946-5240
TELEX: 12721 SQNTL NL TELEX: 364412 INTR 706

PROPHET-T8 SYNTHESIZER
OPERATION MANUAL
By Stanley Jungleib
Manual No. CM1008B
Issued: July, 1983
Copyright© 1983 by
SEQUENTIAL CIRCUITS, INC.
All rights reserved. Printed in USA.
The contents of this manual are the property of
Sequential Circuits, Inc., and are not to be copied
or reproduced without its prior written permission.
Exception is made for reproduction of blank panel
diagrams and memory map (in Section 9) for personal use.
ii CM1008B 7/83

About the Prophet-T8
Early in 1978 Sequential Circuits revolutionized the art of keyboard synthesis with the
Prophet-5, a compact but powerful instrument for the performer. Before the Prophet
appeared it was not possible for a keyboardist to instantly select custom synthesized
sounds and play them polyphonically. Its featured programmability used emergin,
microcomputer technology to control five complete synthesizers (termed voices
fashioned from analog integrated circuits. The Prophet-5 allowed instantaneous
program recall of 120 different "programs" (sounds). It thus captured the attention of
most of the world’s professional synthesists, becoming "the" programmable polyphonic
syntheslzee comparable to "the" electric organ (Hammond) and "the" electric piano
Rhodes).
A second rendering of the Prophet concept was the dual-keyboard Prophet-19. This
highly versatile instrument provided a ten-voice "Single" mode by simultaneously
programming two five-voice synthesizers from one keyboard, or "Split" control from
separate keyboards, or "Double" operation which assigned two different programs to
one keyboard. The -10 included an elaborate polyphonic sequencer which remembered
whatever you played.
The Prophet-T8 integrates the most proven features of its two progenitors with a
wooden, piano-like keyboard which is touch-sensitive (hence, the "T") in three ways.
First, like a piano, the speed at which a key is pressed can control both loudness and
timbre. Unlike a piano, the speed at which a key is released can also control loudness
and timbre: this is velocity sensitivity. Beyond this, pressure sensitivity (sometimes
called “after-touch") is engaged after a key is depressed and can be used to
individually "bend" each key's pitch up or down, modify its loudness, timbre,
modulation depth or rate. This new keyboard radically enhances for synthesists the
crucial physical basis upon which expression and musicality depend, exponentially
multiplying the available aural resources.
The Prophet-T8 actually contains eight individual synthesizers, grouped as four voices
on the Left and four voices on the Right. In Single mode all eight voices are
programmed to sound alike (homophony)--with pitch differences corresponding to (at
most) eight simultaneously-held keys. In Split and Double modes, the four homophonous
Left and Right voices are progammed for different sounds which are played either on
separate sides or simultaneously over the whole of the keyboard.
For its principle sound sources, each voice contains two voltage-controlled oscillators
(VCOs), referred to as OSC A and OSC B. OSC A, OSC B, and a white noise source can
be mixed into a resonant low-pass voltage-controlled filter (VCF) which is followed by
a voltage-controlled amplifier (VCA). The voice timbre and dynamics are shaped by
the filter frequency and amplifier gain parameters which are varied by independent
ADSR envelope generators and the various modulation sources (which include velocity
and pressure). Furthermore, the envelope RELEASE knobs actually control two
alternate programmed release times which are selected with the SECOND RELEASE
switch or footswitch. This allows the footswitch to assume the function of the piano's
sustain pedal, by switching in a longer release time.
M1008B 7/83 iii

Supplementing the basic voice are polyphonic modulation (POLY-MOD) signal routings
within each voice that allow each OSC B and filter envelope generator to function as
modulation sources applied to each OSC A or filter. The pressure modulation routings
are also fully polyphonic, that is, individual to each note. And for each set of four
voices, there is a low-frequency oscillator (LFO) whose modulation depth is adjusted
by the MOD wheel (or key pressure). Finally, the PITCH wheel can raise or lower the
pitch of all voices, or just the Left or Right, by the same interval.
The term "digital-analog hybrid" is often used to describe the Prophet synthesizers. It
means that instead of directly controlling the analog synthesizer voices, the keyboard
and most controls actually input "data" to a microcomputer system which in turn
"programs" the voices. The Prophet-T8 actually has two microcomputers. One micro-
computer is committed to processing the optical (velocity) and pressure sensors in the
keyboard. The second microcomputer generates the sixteen independent oscillator
control voltages (CVs) and the sixteen complex (velocity plus ADSR) envelopes. The
computer memory provides a way to store all of the switch and knob settings which
form a program. The memory retains 128 programs (64 each, Left and Right) even
when the Prophet is turned off, thanks to a small battery with a 10-year life.
Unlimited program storage on common audio cassettes is also available through the
built-in interface. The computer system also keeps the voice oscillators in tune.
Finally, memory also makes possible the 670-note polyphonic real-time sequencer.
The Prophet-T8 includes the MIDI keyboard-computer interface. This system is being
adopted by increasing numbers of manufacturers as a standard means of
interconnecting equipment. For example, connecting one cable between any two MIDI
synthesizers or between a MIDI sequencer and synthesizer will allow one to play the
other and switch programs.
With the range and quality of its sound, multi-responsive keyboard, wealth of
performance features, and ergonomic control panel encouraging instant editing of all
programmable parameters, this latest Prophet promises to be as significant a
development as the first.
iv CM1008B 7/83

Table of Contents
INSTALLATION
1-0 GENERAL 1-1
1-1 HANDLING 1-1
1-2 LINE VOLTAGE SELECTION AND FUSING it
1-3 POWER CONNECTIONS 1-2
1-4 AMPLIFIER AND SPEAKER CONSIDERATIONS 1-3
1-5 | AUDIO OUTPUTS 1-3
1-6 FOOTSWITCHES 1-3
1-7 CASSETTE 1-5
1-8 RECORD ENABLE/PROTECT 1-5
1-9 MIDI 1-5
SECTION2 = BRIEF INSTRUCTIONS
2-0 PRESET MODE 2-1
2-1 PROGRAM EDIT AND RECORD 2-1
2-2 SEQUENCER 2-2
2-3. KEYBOARD 2-2
2-4 CASSETTE 2-3
SECTION3 = BASIC OPERATION
3-0 GENERAL 3-1
3-1 POWER ON 3-1
3-2 PREPARATION 3-1
3-3. PLAYING 3-2
3-4 PITCH AND MOD WHEELS 3-4
3-5 TUNING 3-4
3-6 KEYBOARD MODES 3-5
3-7 UNISON/TRACK AND GLIDE 3-5
3-8 | SEQUENCER 3-7
3-9 IN CASE OF DIFFICULTY 3-8
SECTIONS = PROGRAMMING
4-0 GENERAL co
4-1 EDIT MODE 4-2
4-2 MANUAL MODE 4-3
4-3 RECORD MODE 44
4-4 LINK as
CM1008B 7/33

vi
SYNTHESIZER CONTROLS
GENERAL 5-1
VOICE DESCRIPTION 5-1
OSCILLATOR A 5-3
OSCILLATOR B 5-4
OSCILLATOR NOTES 5-5
MIXER 5-9
FILTER 5-9
FILTER NOTES 5-10
AMPLIFIER 5-12
ENVELOPE GENERATORS 5-12
ENVELOPE GENERATOR NOTES 5-14
VELOCITY SENSITIVITY 5-16
VELOCITY NOTES 5-16
LFO-MOD. 5-18
POLY-MOD 5-19
PRESSURE-MOD 5-20
CASSETTE INTERFACE
GENERAL 6-1
RECORDER AND TAPE SELECTION 6-2
PRECAUTIONS 6-2
SAVE PROGRAMS OR SEQUENCES TO TAPE __ 6-3
LOAD PROGRAMS OR SEQUENCES FROM TAPE Pa
RECORDER COMPATIBILITY TESTING 6-5
MIDI
INTRODUCTION
BASIC OPERATION
INITIALIZATION AND MODES
KEYBOARD INFORMATION
TUNE
PROGRAM SELECT
PROGRAM DUMP
TEMPERMENT
FACTORY PROGRAMS 8-1
MAP AND PANEL BLANKS 9-1
CM1008A 3/83

INSTALLATION
1-0 GENERAL
This
section
describes
installation
procedures
and
connections
which
can
be
made
to
the
back
panel
of
the
Prophet-T8.
See
Figure
1-0.
All
connectors
are
standard
1/4-inch
phone
jacks
(except
for
the
MIDI
jacks,
which
are
5-pin
DIN).
CAUTION! Do not connect the Prophet-T8 to power or switch power on
before following the instructions below.
1-1 HANDLING
The
Prophet-TS
is
a
sophisticated
device
containing
a
state-of-the-art
microcomputer,
sensitive
analog
circuitry,
and
a
wooden
keyboard
action
surrounded
by
optical
and
mechanical
sensors.
The
instrument
should
be
treated
with
as
much
care
as
you
would
provide
an
acoustic
instrument.
Avoid
temperature
and
humidity
extremes.
Shock
or
constant
vibration
can
damage
the
keyboard
or
controls,
and
loosen
connectors
or
socketed
integrated
circuits.
If
you
expect
to
transport
the
Prophet-T8
regularly,
it
is
imperative
to
invest
in
a
professional
"road"
or
"flight"
case
for
it-
These
are
made
by
several
manufacturers
and
should
be
carried
by
your
music
dealer.
If
you
can't
find
a
case,
please
contact
the
SCI
Customer
Service
Department.
1-2 LINE VOLTAGE SELECTION AND FUSING
CAUTION! Check line voltage setting before switching power on.
Disconnect power before switching line voltage.
The
Prophet-T8
has
a
receptacle
on
back
panel
to
which
its
three-wire
power
cable
attaches.
Adjacent
to
this
are
line
voltage
selector
switch
and
the
main
fuse.
Prophet-
T8s
shipped
in
the
U.S.
and
to
Japan
are
usually
set
at
the
factory
for
110V;
to
Europe,
220v.
CML0008A 3/83 1-1

CAUTION! Never switch the line voltage with power switched on.
Check
the
voltage
selector
switch
on
the
back
panel.
If
the
selected
voltage
does
not
match
the
line
voltage,
disconnect
the
power
cord
and
switch
the
voltage
selector.
Replace
the
fuse
according
to
the
selected
line
voltage:
110V: LA
220v: 1/2A
1-3 POWER CONNECTION
WARNING! It is up to you to check the power and ground interconnec-
tions of the Prophet-T8 and all other instruments and equipment you
use to prevent potentially lethal shocks. Sequential Circuits, Inc. is not
responsible for any equipment failure due to incorrect AC power
connections,
and
is
not
liable
for
any
personal
injury
due
to
electrical
shocks as a result of unsafe grounding practices.
The
Prophet-T8
comes
with
a
three-prong
power
plug
to
insure
safe
grounding
with
other
equipment.
The
ground
prong
is
connected
directly
to
the
metal
chassis.
Because
of
this
AC
ground,
a
"ground
loop"
will
often
be
created
when
an
audio
cable
is
connected
between
the
Prophet-T
and
its
amplifier.
As
a
result,
low-level
hum
may
occur.
Defeating
the
AC
ground
with
a
two-prong
adapter
will
usually
defeat
the
hum
but
this
practice
can
set
up
a
shock
hazard
between
the
units.
The
hum
level
will
depend
on
exactly
how
the
synthesizer
and
amplifier
are
connected
to
the
AC.
For
minimal
hum,
use
the
same
AC
outlet
for
the
Prophet-T8
and
its
amplifier.
This
should
reduce
the
hum
to
an
acceptable
level.
1. Connect the power cable to the Prophet-T8.
2.
Check
that
the
Prophet-T8
power
switch
is
in
off
position.
3.
Connect
the
power
cable
to
a
properly-grounded
three-prong
outlet.
Don't
defeat
the
AC-ground.
4.
Plug
all
other
equipment
such
as
effects
devices,
mixers,
amplifiers
and
recorders
into
the
same
outlet.
WARNING!
Do
not
overload.
When
in
doubt,
consult
an
electrician.
5.
As
you
probably
know,
many
older
buildings
and
clubs
are
notorious
for
their
poor
quality
AC
wiring.
We
therefore
urge
you
to
use
one
of
the
several
"ground-checking"
devices
available
on
the
market
to
verify
AC
connections.
1-2
CMI10008A
3/83

1-7 CASSETTE
1. Connect TO TAPE to recorder input (MIC, LINE IN).
2. Connect FROM TAPE to recorder output (EAR, MONITOR, LINE OUT).
Cassette interface operations are explained in Section 6.
1-8 RECORD ENABLE/PROTECT
The PROTECT setting prevents accidental program changes. Unless this switch is set
to ENABLE, the RECORD switch on the control panel will not operate. For more
information, see Section 4, Programming.
1-9 MIDI
1. Connect the OUT jack to the MIDI IN of the sequencer, slave synthesizer, or other
MIDI device.
2. Connect the IN jack to the MIDI OUT of the other MIDI device.
For more information on MIDI, see Section 7.
‘CM10008B 7/83 1-5

BRIEF INSTRUCTIONS
WARNING! Before using this instrument, read instructions in Section 1
concerning proper power connections and grounding.
2-0 PRESET MODE
1. Check that the PITCH wheel is centered.
2. Check that the MOD wheel is set to minimum (notch towards you).
3. Play, and adjust MASTER VOLUME.
4. Check that the MASTER TUNE knob is centered, or tune to a piano, or use A-440
reference (switch on/off).
5. To switch programs, select LEFT or RIGHT then press any two
PROGRAM/SEQUENCE switches.
6. Use the PITCH and MOD wheels.
7. To experiment with different Left/Right program combinations, switch LINK MODE
off. Left and Right program selections will then be independent.
8. After a few minutes, press TUNE. Retune as needed.
For more information, see Section 3.
2-1 PROGRAM EDIT AND RECORD
1, To edit current program, adjust knobs and switches.
2. To cancel changes, press PRESET or re-select program.
3. To record edited program, press RECORD then select desired program destination.
4. To change a program link:
Switch LINK off.
Select program on "other" side.
Re-record desired program (in same location) on "current" side.
For more information, see Section 4.
CM1008B
7/83
21

2-2 SEQUENCER
Record
+ Press RECORD.
2. Press SEQUENCER SELECT/STOP.
3. Select sequence number with a PROGRAM/SEQUENCE switch. It lights.
4. Play. Make desired program changes.
5. To stop recording:
To make a looping sequence press RECORD or hit the SEQUENCER footswitch
in time with the desired ending.
To make a single-play sequence, press SELECT/STOP.
Playback
Tete stat manually:
Press SELECT/STOP.
Then press the desired PROGRAM/SEQUENCE switch.
or
“~ To start by footswitch:
Select desired PROGRAM/SEQUENCE (if not already cued).
Press footswitch.
(To cue footswitch, hold SELECT/STOP then press desired number.)
2. Adjust playback RATE.
3. To save the RATE value, press RECORD (which will not light). Whenever the
sequence is selected it will play at this rate.
4, To stop playback:
A sequence recorded as single-play will stop itself.
or
“ A_ looping sequence can be stopped with the SELECT/STOP switch or
footswitch.
For more information, see Section 3.
2-3 KEYBOARD
SPLIT: To reprogram the split point if the current program is in SPLIT mode, hold the
key which is to be lowest key on the Right side, then press SPLIT.
NORMAL UNISON: Switch UNISON/TRACK on. Play.
CHORD TRACK: Hold chord. Switch UNISON/TRACK on, or press footswitch (if
Normal Unison already). To track a different chord, switch UNISON/TRACK off, then
hold
new
notes,
then
switch
UNISON/TRACK
on,
or
press
footswitch
while
holding
new
notes.
For more information, see Section 3.
2-2 CM1008B 7/83

2-4 CASSETTE,
Connect recorder to Prophet-T8 as diagrammed in Figure 1-0.
For complete instructions, please see Section 6.
SAVE
T. Switch the back-panel RECORD switch to ENABLE.
2.
Insert
cassette
into
recorder
and
rewind
(if
necessary).
3.
Choose
storage
mode.
128
programs:
Check
that
SEQUENCER
SELECT/STOP
is
off
and
two
program
digits are
displayed.
Or,
8
sequences:
Press
SEQUENCER
SELECT/STOP.
Or,
S
programs:
Select
LEFT
or
RIGHT,
then
enter
one
program
digit
for
the
desired "bank."
(E.g.
Select
RIGHT
and
6
to
store
R61
through
R68.)
4.
Switch
RECORD
MODE
on.
5.
Place
recorder
into
record
and
wait
5
seconds.
6.
Press
the
SAVE
TO
TAPE
switch.
SAVE
TO
TAPE
LED
will
remain
lit.
7.
Check
the
record
level
(0
dB).
8.
When
the
LOAD
FROM
TAPE
LED
blinks,
stop
the
recorder.
VERIFY
9.
Now the
recording
must
be
verified.
Rewind.
10.
Check
playback
level.
11.
Place
recorder
into
play
and
wait
until
the
pilot
tone
appears.
12. Press the (blinking) LOAD FROM TAPE switch. The LED will stay lit.
13. When LOAD FROM TAPE goes out, stop the recorder. With tape verification
completed, the Prophet returns itself to the current program.
14, If the LOAD FROM TAPE LED instead blinks, a tape error has occurred. Try
verification again, by repeating from step 9.
(over)
CM1008B 7/83 2-3

LOAD
T. Switch the back-panel RECORD switch to ENABLE.
2. Insert cassette into recorder and rewind (if necessary).
3. Choose mode: 128 programs, or eight sequences or programs, as in step 3, above.
4. Switch RECORD MODE on.
5. Check playback level.
6. Place recorder into play and wait until the pilot tone appears.
7. Press LOAD FROM TAPE. LOAD FROM TAPE LED will remain lit.
8. When LOAD FROM TAPE goes out, stop the recorder. With tape loading completed,
the Prophet returns itself to the current program.
9. If LOAD FROM TAPE instead blinks, a tape error has occurred. Try loading again.
24 M1008B 7/83

BASIC OPERATION
3-0 GENERAL.
This section contains information essential for basic operation. Programming, the
Synthesizer Controls, Factory Programs, and Cassette Interface are each detailed in
separate sections.
NOTE: If you have trouble with any of these basic operations, please
see page 3-9, In Case of Difficulty.
3-1 POWER ON
1, Install the Prophet-T8 according to Section 1, Installation.
2. Switch Prophet-T8 power on with its back-panel switch, which is on the left as you
face the keyboard. The switch will light.
3. Switch power on to your preamp or mixer, if used, then switch amplifier power on.
3-2 PREPARATION
When power is first switched on, the TUNE switch light-emitting diode (LED) will light
to indicate that the microcomputer is tuning the oscillators. The rest of the control
panel will remain unlit for these few seconds. The Prophet-T8 cannot be played while
TUNE is lit.
CAUTION! Before playing any key, first check that the MASTER
VOLUME knob is reduced to 0. This may keep you from accidentally
blowing-out speakers (or ears).
1, Check that the PITCH wheel is centered.
2. Check that the MOD wheel is fully down (minimum).
3. Check that the BALANCE knob is centered.
CMLOO8A 3/83 3-1

4. While playing, gradually raise MASTER VOLUME until the synth can be heard.
5. For optimum signal-to-noise ratio, set the Prophet-T8's MASTER VOLUME knob as
high as possible. Then overall audio system gain (and noise) will be reduced by the
system mixer or the power amplifier level control.
6. If necessary, readjust the BALANCE and MASTER VOLUME knobs while playing
both halves of the keyboard.
NOTE: Do not adjust the PROG VOLUME knob. This is a programmed
control for balancing Left and Right program loudness. It should not be
used to correct amplifier or speaker imbalance.
3-3 PLAYING
After its initial tuning, the Prophet-T8 awakens in Preset mode. This is indicated by
the lit PRESET MODE switch. In Preset mode, the Left and Right synthesizer voices
are "patched" by programs which reside in memory and are selected with the
PROGRAMMER switches.
There is only one "current" program which can be accessed and displayed on the
control panel (even though In Split and Double modes the Left and Right programs are
simultaneously in effect). The current program side is selected with the LEFT and
RIGHT PROGRAMMER switches. The lit switch indicates the side of the current
program, while the numerical PROGRAM/SEQUENCE switches select the specific
program in that side. The Left and Right sides each have 64 programs designated 11
through 88, (without Os or 9s). In other words, there are two programs ‘the same
number; one Left and one Right. So specific programs are designated as LI1, or R82,
for example. R11 is automatically selected at first.
The Prophet-T8 is shipped ready-to-play with 128 "Factory" Programs already in its
memory. All of these are mapped and diagrammed in Section 8. To select a program,
first select the side (if it is not already indicated), then enter two program digits with
the PROGRAM/SEQUENCE switches. These will appear on the LEFT or RIGHT
PROGRAM numeric display. The new program will activate when you enter the second
igit.
As you find your way around the Factory Programs, you may notice that changing the
Right program, for example, usually changes the Left program as well. This is a
function of the Link feature, which is also enabled on power-up. To separately control
the Right and Left, switch LINK off. Link is explained more fully on page 4-5.
Also as you select programs note that the keyboard is programmed for SINGLE, SPLIT,
or DOUBLE operation as indicated by these KEYBOARD switches. Single mode gives
eight voices of the current program over the whole keyboard. Split mode gives one
four-voice program on the Left, and another four-voice program on the Right. Double
mode gives two simultaneous four-voice programs over the whole keyboard. The
keyboard modes are more fully explained in page 3-5.
Be sure to investigate the effects available by using velocity on both attack and
release, and by engaging pressure modulation after the key is initially pressed. The
velocity and pressure effects differ widely between programs.
3-2 CM1008B 7/83

3-4 PITCH AND MOD WHEELS
The
PITCH
and
MOD
wheels
to
the
left
of
the
keyboard
are
performance
tools
which
may
take
some
practice
to
master.
The
wheels
are
monophonic.
That
is,
when
enabled,
both
wheels
affect
all
Left
or
Right
voices
uniformly:
all
voices
are
pitch-bent
by
the
same
interval
and
modulated
to
the
same
depth.
The
PITCH
wheel
is
normally
left
in
its
center-detent
position,
from
which
it
is
possible
to
"bend"
oscillator
pitch
up
or
down
by
about
a
third.
The MOD wheel sets the modulation level. When the wheel is left down,
and minimum modulation will occur. (Minimum modulation is determined by the
programmed LFO-MOD INITIAL AMT knob.) When the wheel is advanced fully up,
modulation will be maximum.
The
ENABLE
WHEELS
switch
(located
above
the
LFO-MOD
module)
is
programmed
independently
by
the
current
Left and
Right
programs,
allowing
selective
use
of
the
wheels.
For
example,
if
soloing
on
the
Right
over
a
"comping"
sequence
played
on
the
Left,
the
Right
program
would
have
ENABLE
WHEELS
on,
while
the
Left
program
would
program
the
wheels
off
so
that
bending
or
modulating
the
solo
line
wouldn't
also
bend
and
modulate
the
comping
as
well.
3-5 TUNING
‘The MASTER TUNE knob is used to tune the whole synthesizer to another instrument,
such as a piano. Or the built-in A-440 reference can be used as a reference. (Note that
for accurate tuning, the PITCH wheel must be centered.)
As mentioned above, the microcomputer automatically tunes the oscillators when the
Prophet-TS is first switched on. But as the instrument warms-up, the temperature
change causes the oscillators to drift. So it will ocassionally be necessary to retune,
particularly during the first few minutes of operation. After 30 minutes or so the
instrument should not have to be retuned very often. On the other hand, the more
often you activate TUNE, the more accurate the tuning will be. You will soon learn to
hear when the Prophet-T8 needs to be tuned.
To retune, simply press the TUNE switch. Except for this switch, the control panel will
go dark while tuning is in progress. Retuning takes 5 to 25 seconds, depending on how
far out of tune the oscillators have drifted since their last tuning. The more often you
tune, the less time each tuning takes.
When tuning is concluded, the Prophet-T8 returns to exactly its state before the
tuning. (Even unrecorded Edit mode changes are retained.) It may be necessary to
slightly readjust MASTER TUNE.
The TUNE switch will not operate while the -T8 is loading to or saving from tape.
3-4 CM1008A 3/83

3-6 KEYBOARD MODES.
In playing through the Factory Programs you must have noticed the keyboard mode
switching between unified, separate or simultaneous sounds over the Left and Right,
and between monophonic (unison) lines and polyphonic capacity. The synthesizer voices
are assigned to particular keys according to the settings of the KEYBOARD and
adjacent UNSION/TRACK switches in the current progeam. These features are
explained in this and the following paragraph.
Single Mode: When the SINGLE KEYBOARD switch is on, the current program controls
all eight voices, providing eight homophonous (same-sounding) voices over the whole
keyboard. If more than eight keys are held down at the same time, the earliest-used
voices are reassigned first. For example: playing and holding C, D, E, F, G, A, B, and C
assigns all the available voices. Adding another key, such as D#, to this cluster results
in D, E, F, G, A, B, C and Dif being sustained. The first C disappears when the Diff is
played. Each new key played is assigned to the earliest-used voice, which must give up
the key it was sounding. (If a key is repeated, the voice assignment doesn't change.)
Split Mode: If SPLIT KEYBOARD is on, the Left and Right voices will have different
Programs. The active program numbers are indicated in the PROGRAM DISPLAY. The
side, Left or Right, which is not current will be programmed by whatever program was
last selected there, unless LINK is on. If LINK is on, the program on the non-current
side will be the program which has been linked to the current program. The position on
the
keyboard
at
which
the
Left/Right
split
occurs
can
be
moved
at
will
when
the
program
is
recorded
or
edited.
(For
further
information,
see
page
4-4.)
Double
Mode:
If
DOUBLE
KEYBOARD
is
on,
the
Left
and
Right
synthesizers
will
also
have
different
programs,
but
they
will
be
played
simultaneously
to
create
very
complex
sounds.
This
results
in
a
four-voice
capacity
over
the
whole
keyboard.
The
non-current
side
will
be
programmed
by
whatever
program
was
last
selected
there,
unless
LINK
is
on.
If
LINK
is
on,
the
non-current
program
will
be
the
program
which
has
been
linked
to
the
current
program.
3-7 UNISON/TRACK AND GLIDE
In Single mode the keyboard continuously reassigns each new note to one of eight
voices
in
rotation.
In
Split
and
Double
modes
the
assignment
occurs
within
the
four
Left
and
four
Right
synthesizers.
In
all
modes,
whenever
a
key
is
struck
or
restruck,
the
envelope
generators
(explained
in
Section
5)
are
triggered
to
proceed
through
their
attack
and
decay
periods.
These
repeated
attacks
and
decays
are
required
to
articulate
polyphony.
Therefore
we
say
the
Prophet-T8
keyboard
normally
operates
in
last-note
priority, with multiple-triggering.
But
there
are
several
options
to
this
voice
assignment
and
triggering
scheme
available,
which
can
be
selected
with
the
UNISON/TRACK
switch
or
footswitch:
Normal
Unison,
Tracking
Unison,
and
Simple
Unison.
Normal
Unison:
To
enable,
simply
switch
UNISON/TRACK
on,
or
press
the
footswitch
once.
If
the
current
program
is
in
Single
mode,
all
eight
voices
will
be
assigned
to
the
last
(i.e.,
most
recent)
key
played
anywhere.
If
the
current
program
is
in
Split
mode,
four
voices
will
be
assigned
to
the
last
key
on
the
current
side.
(The
Unison
mode
of
the
other
side
is
programmed
independently.)
CM1008B 7/83 3-5

NOTE: Normal Unison can only be switched off with the UNISON/TRACK switch (not
with the footswitch).
In Normal Unison, if several keys are played at once, the last key will sound.
Releasing the last key that was pressed causes the lowest pressed key to sound. The
keyboard
will
also
change
from
multiple-
to
single
-t/iggeting.
This
keyooard
mode
was
conventionalized by the Mini-Moog monophonic synthesizer, and requires--but also
allows--a somewhat different keyboard technique. Instead of retriggering with each
keystroke, the envelopes will only retrigger if the previous key is completely released
before the new key is pressed. This requires a stacatto touch. If you play legato, the
envelopes will only trigger on the first note, while the rest of the phrase will be
sounded by the sustain settings of the envelopes. With practice, the system allows you
to selectively trigger notes by touch.
In any Unison mode with single-triggering (and without velocity), the sustain level does
not change as two notes are played legato. But velocity sensi complicates
matters by allowing great differences in sustain levels between legato notes. The
problem is how to move between the two sustain levels without retriggering attack and
decay. The solution, which you should be able to demonstrate to yourself, is that if the
next note is faster (louder) the envelope level will increase to the new sustain level at
the attack rate. If the new note is slower (softer) the envelope level will decrease to
the new sustain level at the decay rate. By not retriggering both the attack and decay
periods, the legato quality is preserved.
Tracking Unison: Play and hold any chord, then press UNISON/TRACK or hit the
footswitch
once.
This
"latches"
the
chord,
so
that
any
key
you
play
becomes
the
root,
while
the
upper
intervals
follow
along
(track).
In
Single
mode
the
chord
can
have
eight
voices.
Split
and
Double
modes
limit
tracking
to
four
voices.
The
chord
that
is
latched
into UNISON/TRACK is not retained by the current program.
NOTE: Tracking Unison can only be switched off with the UNISION/TRACK
switch
(not
with
the
footswitch).
If
Tracking
Unison
is
on,
pressing
the
footswitch
will
either
latch
a
new chord
or
switch
the
keyboard
to
Normal
Unison, depending on whether keys are held or not.
Simple
Unison:
Play
and
hold
any
one
key,
then
press
UNISON/TRACK.
In
effect,
this
assigns
one
voice
for
tracking.
Simple
Unison
will
yield
a
thinner
sound
than
Normal
Unison,
where
four
or
eight
voices
sound
simultaneously.
Glide: Lastly there is the GLIDE knob, which operates identically in all modes. When
set
(or
programmed)
to
0,
there
is
no
effect,
because
the
oscillator
control
voltages
are
allowed
to
step
instantly
between
the
discrete
voltages
required
to
sound
specific
Pitches.
As
GLIDE
is
advanced,
the
rate
at
which
the
oscillator
control
voltages
change
is
decreased.
This
introduces
"portamento"
between
the
notes
which
can
be
subtle or quite extreme.
3-6
CM1008B
7/83