There are two sources of modulation: MIDI (CC and Pitch Bend) and the CV inputs. Coral adds the knob position and the CV input to get the value of a voice parameter. The last CC value replaces the knob position. This applies when a CV is assigned to that voice or part.
- Knob value is unipolar, except the bipolar parameters: Pan, Filter envelope and Frequency.
- CV modulation is bipolar: ±5 V.
- CC is unipolar and overrides the knob value.
Parameter value = knob (or CC) + CV modulation.
Each part can be modulated separately, which lets you build richer, more complex sounds.
4.1 CV Modulation
The Atk/Dec, Filter, Harm, Timbre, Morph, Trig, Amp and Oct CV inputs affect the voices of the selected part only. By default there is one part, so all voices respond.
Poly and Trigger Modes (PolyCV)
The PolyCV setting in the options ring sets how CV and the trigger drive the voices. It has six modes:
| Mode | Behaviour |
|---|---|
| 0 · Unison | All voices play in unison. |
| 1 · Poly CV | Different CV pitch values trigger different voices. You can play Coral polyphonically from a single Oct CV and one trigger. |
| 2 · Chord hold | Holds a chord across voices. |
| 3 · Chord arp | Arpeggiates the held chord. |
| 4 · Echo | Echo mode. |
| 5 · Echo | Second echo mode. |
NOTE In modes 2 to 5, incoming MIDI notes take over the pitch. You can play chords and echoes from a keyboard as well as from CV.
CV Inputs
| Input | Effect |
|---|---|
| Atk/Dec | Increases or decreases attack, decay and release of both the Amp and Mod envelopes. Negative voltages make the sound pluckier, positive voltages softer and longer. |
| Filter | Positive voltages raise the filter cutoff, negative lower it. |
| Harm, Timbre, Morph | Positive voltages apply positive modulation on these engine parameters, negative apply negative. |
| Trig | Triggers the internal envelopes. |
| Amp | Controls the amplifier level. It scales every engine. |
| Oct | CV/Oct pitch. The Oct and Frequency (fine) knobs are taken into account for the final pitch. |
| Part | The voltage on this input selects which part the other CV inputs affect. |
The ADSR trimmers also work as bipolar attenuators for the CV inputs below them. Amp Atk scales the Atk/Dec CV. Amp Dec scales the Filter CV. Sust scales the Harm CV. Mod Atk scales the Timbre CV. Mod Dec scales the Morph CV.
4.2 Part CV Input
One way to choose which part the CV modulation affects is the Part CV jack. Only 0 to +5 V is considered. With two parts, the first is addressed between 0 and 2.5 V and the second between 2.5 and 5 V. There is a little hysteresis to avoid jumps at the edges.
NOTE Turn on the CV part to engine option on the options ring, LED 3. The Part CV then selects the engine instead of the part.
4.3 The CV Assign Screen
Leave the Part CV jack unpatched. You can then send the front-panel CV modulation to one part with the CV Assign screen. This is the purple stop in the encoder click cycle. Turn the encoder to choose the part. Click to confirm. Any voltage on the Part CV jack overrides this selection.
Figure 4.1. CV Assign ring: turn to select the part, press to assign and leave.
4.4 MIDI Modulation
With MIDI CC messages you can modulate any parameter inside Coral. Messages are filtered by MIDI channel and applied to the part on that channel. CC is unipolar and overrides the knob value. See Chapter 7 for the full CC table.