Guide: OXI Coral Guide EP.5: Voice Setup and Multitimbrality

Welcome to EP.5 of the OXI Coral guide series. This time, I’ll be covering voice setup and multitimbrality.

By assigning different MIDI channels to Coral’s 8 voices, you can treat each one as an independent part. In the video we’re referencing this time, an OXI Instruments team member plays Coral live, starting from a chord pattern and progressively layering in bass, drums, and a lead melody to build up a multitimbral jam-performance setup. In this article, I’ll follow along with the flow of the video and walk through how to assign MIDI channels to each voice, how to design sounds at the part level, how to route CV modulation, and how to save and load settings to and from the SD card.

• The Multi-Part Concept
• Selecting Voices and Creating Parts
• Dialing In the Bass Sound
• Adding the Drum Part
• CC Modulation via MIDI
• Adding the Lead Melody
• Assigning CV Modulation
• Saving to and Loading from the SD Card
• Tips

The Multi-Part Concept#

On Coral, voices that share the same MIDI channel are grouped together as a single part. By default, all 8 voices are assigned to MIDI channel 1, so there’s only one part.

When you change a voice to a different MIDI channel, a new part is automatically created. For example, if you change Voice 1 to MIDI channel 2, you end up with two parts: “Voice 1 on channel 2” and “Voices 2-8 on channel 1.” Each part can have its own engine settings, envelope, and effects amounts, so a single unit can handle multiple tones like bass, chords, drums, and lead simultaneously.

The video’s demonstration begins with all 8 voices assigned to MIDI channel 1 (the default state), playing a chord pattern. The chords are received on MIDI channel 1 and sound polyphonically across all 8 voices. From there, MIDI channels are gradually assigned to individual voices, adding new parts one by one.

Selecting Voices and Creating Parts#

Selecting a Voice#

Press and hold the encoder while turning it to cycle through voice selections. The LED ring display indicates the current voice selection state.

Here’s what the colors mean:

• Bluish (turquoise): An individual voice is selected
• Greenish turquoise: An entire part is selected
• All LEDs lit: All voices are selected (default state)

Changing the MIDI Channel#

While the voice is still selected (encoder held down), turn the harm/midi knob to change the MIDI channel. This knob controls harm as the primary parameter and MIDI channel as the secondary parameter. Holding the encoder down switches it into the secondary MIDI channel mode.

Once you’ve turned the knob to the desired MIDI channel, release the encoder. Voice 1 is now assigned to the new MIDI channel, and a new part has been created.

Creating the Bass Part#

In the video, Voice 1 is selected and set to MIDI channel 2 in order to add a bass line. This creates the following two parts:

• Part 1: Voices 2-8 (for chords, MIDI channel 1)
• Part 2: Voice 1 (for bass, MIDI channel 2)

Press and hold the encoder while turning it, and you’ll cycle through all-voices selection → part selection → individual voice selection. In part-selection mode, the LEDs light up in a greenish turquoise to show which voices belong to that part.

Dialing In the Bass Sound#

With the bass part (Voice 1) selected, you adjust the engine and parameters to shape a proper bass tone. By default it uses the same settings as the chord part, so in the video the following changes are made:

• Remove reverb: Turn the space knob down to set the reverb send to 0
• Open the filter: Raise the filter cutoff to brighten the sound
• Shorten the attack: Use the amp atk knob to shorten the attack time for a more bass-like response
• Change the engine: Turn the encoder to switch to a different engine

Each parameter’s knob position may differ from its stored value, so you need to move the knob once to complete the “catch-up” before your changes take effect.

Adding the Drum Part#

Next, the video adds a drum part. Three voices are dedicated to drums here:

• Voice 8: Kick (MIDI channel 8)
• Voice 7: Snare (MIDI channel 7)
• Voice 6: Hi-hat (MIDI channel 6)

For each voice, press and hold the encoder while turning to select the voice, then use the harm/midi knob to assign a MIDI channel.

Kick Sound Settings#

With Voice 8 (kick) selected, the video sets things up like this:

• Turn the encoder to switch to the Kick Model engine
• Set the space knob reverb to 0 (a kick is typically dry)
• Raise the filter cutoff to the max
• Adjust the octave with the oct knob
• Fine-tune the pitch with the tune knob

Snare and Hi-Hat Settings#

The snare (Voice 7) and hi-hat (Voice 6) are set up the same way.

Snare (Voice 7):

• Switch to the Snare Synth engine
• Use the harm knob to balance the harmonic and noise components
• Use the mod dr knob to adjust the internal envelope decay

Hi-hat (Voice 6):

• Switch to the Hi Hat Synth engine
• Raise the filter cutoff to the max
• Adjust the octave with the oct knob

For each of the drum engines (Kick Model, Snare Synth, Hi Hat Synth), the mod dr knob controls the decay of the internal envelope. This value has a big impact on the length and character of the drum sound, so it’s worth tuning per engine.

CC Modulation via MIDI#

Since each part is identified by its MIDI channel, you can send CC messages from an external sequencer to control parameters on each part independently. CC messages are filtered by MIDI channel and only affect the part on the matching channel.

In the video, CC automation is set up on the snare (channel 7), controlling the reverb send in real time. CCs are unipolar and override the knob’s current value.

Adding the Lead Melody#

Finally, the video adds a part for the lead melody. Voice 5 is set to MIDI channel 3.

Here’s how the lead sound is dialed in on the video:

• Turn the encoder to change the engine (2 OP FM, Waveshaping, etc.)
• Use the space knob to add a moderate amount of reverb send
• Add a chorus effect with the chorus knob to widen the sound

With this, you have the following 6 parts in place:

Assigning CV Modulation#

To assign CV modulation to a specific part, use the CV Assign screen.

Here’s how to get to the CV Assign screen:

1. From the main view (voice status), tap the encoder three times quickly
2. The display cycles through the Load/Save screen and then the CV Assign screen
3. Once you’re on the CV Assign screen (purple), turn the encoder to select the part you want the CV modulation to affect
4. Tap once more to confirm

In the video, the lead (Voice 5, channel 3) is selected and CV Assign is confirmed, showing that the timbre parameter modulation from the CV input only affects the lead part.

Saving to and Loading from the SD Card#

You can save your multi-part setup to the SD card.

Saving#

1. Tap the encoder twice to enter the Save screen
2. Turn the encoder to select a save slot
3. Tap once more to confirm

Loading#

1. Tap the encoder once to enter the Load screen
2. Turn the encoder to select the slot to load
3. Tap to confirm

Tips#

• Start simple: Rather than trying to create many parts from the beginning, it’s recommended to start with just 2 parts (e.g., chords + bass) to get used to the workflow before expanding
• Manage parts by MIDI channel: Mapping parts 1-8 (MIDI channels 1-8) to tracks on your external sequencer gives you intuitive control
• mod dr on drum engines: On the drum-specific engines (Kick Model, Snare Synth, Hi Hat Synth), the mod dr knob controls the decay of the internal envelope. Because this parameter has a major effect on sound length and character, it’s one of the most important values to dial in first
• Reset with Voice/Part Reset: To return all voices to MIDI channel 1, press and hold the encoder for 5 seconds or more to reset (a red LED animation will appear)