Loading ...
Loading ...
Loading ...
5.2.7. Two Op. FM
The Two Op. FM Oscillator is a two-operator frequency modulation source. That's all fine...
but what's an 'operator'?
FM synthesis
is based around one oscillator changing the phase of another in a controlled
way, using frequency relationships that could be harmonic or inharmonic, meaning not
part of the usual series of harmonic overtones. Dr. John Chowning of Stanford University
developed FM using collections of sine wave oscillators (called operators) controlling one
another. The technology was licensed to Yamaha, who created a wide variety of FM
synthesizers that could easily create realistic bell-like tones that were difficult for analog
synths to make. One of these was the DX7, one of the most popular synthesizers in history.
While this Oscillator uses only two operators controlling each other's phase (the most
common Yamaha synths used either four or six operators), it's still capable of a wide variety
of tones ranging from rich organs to clangorous bells.
Ratio: sets the frequency ratio between the two operators. Ratios like 2:1 (an octave) or 1.5:1
(a perfect fifth) will produce relatively clean sets of harmonics, while other ratios will create
inharmonic timbres.
Amount: changes the
modulation index
, which is the amount of modulation sent to the
Operator 1. All you need to know is that turning it up will add more overtones, creating a
distinctive bright timbre. Experimentation is key here.
Feedback: sets how much of Operator 2's output is fed back into itself to modulate its own
phase. Feedback loops like this are another fundamental part of FM synthesis, and they can
add all types of extra overtones and even detuning effects. Again, experiment!
Freak Out: a combination of operators controlling one another in a certain way is called an
algorithm
. One of the most common and useful algorithms in 4-operator FM is a simple mix of two pairs
of operators, one in each pair modulating the other.
If you set both of the MiniFreak's Oscillators to Two Op. FM and mix them together, you'll
have created this exact algorithm, with one important difference: the traditional algorithm
has only one feedback loop, but this arrangement on the MiniFreak gives you two of them!
Arturia - User Manual MiniFreak - The Digital Oscillators 26
Loading ...
Loading ...
Loading ...