Dave Smith Instruments Prophet 12 User Manual

Prophet 12 Manual Addendum

OS Version 1.3

Prophet 12 OS version 1.3 adds a number of new features not covered in the
main Operation Manual. These features are described in the following Addendum
in the order shown below.

New Features in OS 1.3

• Linear frequency modulation for classic DX-style FM

• Assignable voice-stacking in Unison mode

• MIDI note output for the arpeggiator

• New modulation destinations: Slop, Osc All Shape, All Delays

• Disable screen saver option for OLED display

• Soft knobs allow Playlist list and set selection

• Support for alternate tunings

Checking Your Operating System Version

If you’ve just purchased your Prophet 12 new, OS 1.3 should already be installed. If
you purchased your Prophet 12 prior to Dec, 2015 and wish to use the new features
described above, you’ll need to update your OS to version 1.3 or later.

To update your Prophet 12 OS, you’ll need a computer and a USB cable, or a MIDI
cable and MIDI interface. To download the latest version of the Prophet 12 OS along
with instructions on how to perform a system update, visit the DSI website at:

http://www.davesmithinstruments.com/updating-prophet-12-os/

To check your OS version:

1. Press the global button. The screen displays the version of the currently
loaded OS.

2. If your OS is out of date, download the latest version from the URL above and
update your instrument using the instructions included with the download.

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New DX-Style Linear FM

The Prophet 12 now provides a choice between its original exponential method
of FM (frequency modulation), and linear FM, which is the type found on the
classic Yamaha DX-series of synthesizers. Exponential FM is selected by default.
To choose linear FM, you’ll need to use the menus in the Prophet 12 display.

To choose linear FM:

1. Press the front panel oscillator 1 selector to show the oscillator controls in
the display.

2. Press soft button 4 (osc level).

3. Use soft knob 4 (fm mode) to set the FM mode to linear.

Level SyncSub Osc FM Mode

127

LEVEL

Osc Shape Osc Tuning Osc Mode

Choosing Linear FM

0

SYNCSUB OSC

Linear

FM MODE

Osc Level

Select FM
mode here

Creating Sounds with FM

To create sounds with FM you’ll use one oscillator (the modulator) to modulate
the frequency of another oscillator (the carrier). This creates a new waveform
that has additional harmonics known as sidebands.

The type of sidebands created depends on the tuning relationship between the
modulator and the carrier. If both are tuned to the same note or a multiple of
the same note (for example, carrier = C2, modulator = C3) then the harmonics
created will be harmonically related and “in tune.”

However, if the modulator is tuned to a note that is not the same as the carrier or
is not a multiple of it (for example, carrier = C2, modulator = D#2) the sidebands
won’t be harmonically related and the resulting sound will be clangorous. This is
why FM synthesis is well-known for creating metallic, bell-like timbres.

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The amount of sidebands created is directly related to the amount of modulation

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applied (the fm amount parameter) and also the waveform of the modulator. The
greater the fm amount setting, the more sidebands produced, and the “brighter”
the sound will become. Think of the fm amount as being similar to a low pass

lter cutoff: the higher the setting, the brighter the resulting waveform.

A modulator with a large number of harmonics, (a sawtooth wave, for example),
will create many more sidebands than a modulator with a no harmonics (a sine
wave, for example).

The original DX-7 synthesizer provided only sine waves for its oscillators (called opera-

tors in DX-7 terms). The Prophet 12, however, supplies a much broader range of waveshape

choices. Experiment with different waveshapes for both the carrier and modulator to see how
this changes the harmonic content of a sound.

The Default Carrier/Modulator Relationship

If you look at the oscillators section on the front panel of the Prophet 12, you’ll
see arrows between the oscillator selector buttons. These indicate the default
carrier/modulator relationship between the oscillators. The arrows indicate which
oscillator modulates which.

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Default FM carrier/modulator relationship between the 4 oscillators on the front panel

• Turning up the FM amount on Oscillator 1 causes it to be modulated by Oscillator 2.

• Turning up the FM amount on Oscillator 2 causes it to be modulated by Oscillator 3.

• Turning up the FM amount on Oscillator 3 causes it to be modulated by Oscillator 4.

• Turning up the FM amount on Oscillator 4 causes it to be modulated by Oscillator 1.

Though the above shows the default oscillator relationships for performing FM, you can
actually route any oscillator to another using the modulation matrix. This also allows you to
modulate the same carrier oscillator with more than one modulator oscillator. When doing so,
set the wave reset parameter to on for the various oscillators to avoid phase cancellation.

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When creating a typical linear FM sound, you’ll want to turn up the output level
of the carrier oscillator so that you can hear it, but turn down the output level of
the modulator oscillator so that you don’t hear it.

To create a basic linear FM sound:

1. Press the global button, then turn soft knob 1 and select basic patch.

2. Press soft button 1 (write now). Then press the global button again to exit
the Global menu.

3. Press the front panel oscillator 1 selector to show the oscillator controls in
the display, then press soft button 4 (osc level).

4. Use soft knob 4 (fm mode) to set the FM mode to linear. (Setting any oscil­lator to linear FM sets all oscillators to linear FM.)

5. Turn soft knob 1 to set the oscillator level to 127.

6. Turn the shape/noise knob and select sine as the waveshape.

7. Turn the fm knob to 150.

8. Press the Oscillator 2 selector on the front panel, then turn the shape/noise
knob and select sine as the waveshape.

9. Turn the pitch knob for Oscillator 2 and listen to the effect on the tone of
Oscillator 1.

10. Repeat steps 5-7 for Oscillator 3 and Oscillator 4. Use Oscillator 3 as the
carrier and Oscillator 4 as the modulator.

11. Remember to leave the output level at zero for the modulators (oscillators
2 and 4) so that you don’t hear them. It’s only necessary to hear the carriers
(oscillators 1 and 3).

Adjust the Pitch (note) value of Oscillators 2 and 4 (the modulators) to hear how this
changes the timbre of your sound. For metallic, bell-like sounds, tune the pitch of Oscillator 2
and 4 to something other than C.

For evolving timbres, try routing Auxiliary Envelope 3 or 4 to the FM Amount parameter
of Oscillator 1 and/or 3. The envelope causes the FM amount to change over time, thus chang­ing the resulting waveform either subtly or drastically, depending on the envelope shape.

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