peterall / eurorack-prologue

Eurorack Oscillators for Korg prologue, minilogue xd and Nu:tekt NTS-1

Eurorack Oscillators for Korg prologue, minilogue xd and Nu:tekt NTS-1

Ports of some of Mutable Instruments (tm) oscillators to the Korg "logue" multi-engine.

See releases for latest binaries.

Macro Oscillator 2 (based on Plaits)

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Name	Oscillator	Shape operation	Shift-shape operation
mo2_va	Pair of classic waveforms	Shape	Pulse width
mo2_wsh	Waveshaping oscillator	Amount	Waveform
mo2_fm	Two operator FM	Modulation index	Frequency ratio
mo2_grn	Granular formant oscillator	Frequency ratio	Formant frequency
mo2_add	Harmonic oscillator	Index of prominent harmonic	Bump shape
mo2_wta*	Wavetable: Additive (2x sine, quadratic, comb)	Row index	Column index
mo2_wtb*	Wavetable: Additive (pair, triangle stack, 2x drawbar)	Row index	Column index
mo2_wtc*	Wavetable: Formantish (trisaw, sawtri, burst, bandpass formant)	Row index	Column index
mo2_wtd*	Wavetable: Formantish (formant, digi_formant, pulse, sine power)	Row index	Column index
mo2_wte*	Wavetable: Braids (male, choir, digi, drone)	Row index	Column index
mo2_wtf*	Wavetable: Braids (metal, fant, 2x unknown)	Row index	Column index
mo2_string	Inharmonic string model	Decay	Brightness

* Due to the 32k size constraint in the multi-engine the Wavetable oscillator is split into 6 oscillators of 8 rows (scannable by Shape) by 4 columns (scannable by Shift-shape)

Parameters

In the Multi-engine menu you can find additional parameters for the oscillators.

Parameter 1 is oscillator specific and controls whichever parameter is not mapped to Shape or Shift-shape.

Parameter 2 sets the mix between the oscillator out and aux.

LFO Target sets the Shape LFO target, see list below.

LFO2 Rate is rate of LFO2.

LFO2 Int is intensity (depth) of LFO2.

LFO2 Target sets the target for LFO2 according to the list below.

LFO2

The oscillator has a built-in additional cosine key-synced LFO which can module an internal parameter (set with the LFO2 Target parameter in the oscillator menu):

LFO Target	Parameter	Notes
1	Shape
2	Shift-shape
3	Parameter 1	Not implemented for Wavetable oscillator
4	Parameter 2
5	Pitch
6	reserved (Amplitude?)
7	LFO2 Rate
8	LFO2 Int

For more information please read the excellent Mutable Instruments Plaits documentation.

Tips

Many parameters 'neutral' settings are in center position, such as va Detune or fm Feedback, however the prologue defaults all parameters to the lowest value, hence get used to going into the menus and set the first parameter to 50% when instantiating the oscillator.

Modal Resonator (based on Elements)

Physical modeling synthesis

Name	Oscillator
mod s	Strike exciter with modal resonator

Parameters

Parameter	Parameter	LFO Target	Notes
Shape knob	Resonator position	1	Position where the mallet strikes, has a comb-filtering effect.
Shift + Shape knob	Resonator geometry	2	Geometry and stiffness of resonator. Set to 25-30% for a nice tuned sound.
Strength menu	Strike strength	3	Mallet strength, high values causes the strike to bleed into the resonator output.
Mallet menu	Strike mallet	4	Type of mallet, over 70% is bouncing particles.
Timbre menu	Strike timbre	5	Brightness/speed of the excitation.
Damping menu	Resonator damping	6	The rate of energy dissipation in the resonator. High values cause long release effect.
Brightness menu	Resonator brightness	7	Muting of high frequencies
LFO Target menu	multi-engine Shape LFO target		Sets which parameter is modulated by the Shape LFO (see LFO Target column)

For more information please read the excellent Mutable Instruments Elements documentation.

Limitations

Due to compute and memory (32K!) limitations in the prologue multi-engine quite a few short-cuts had to be taken:

• Only the Strike exciter is used
• Sample-player and Granular sample-player mallet-modes did not fit in memory
• Resonator filter bank is reduced to 24+2 filters from 52+8
• Resonator filters are recomputed one per block instead all-ish every block
• Samplerate is 24KHz vs 32KHz in Elements

Sounds pretty great IMO but go buy Elements for the real experience!

Tips

When you first select the oscillator it will make no sound, all parameters are at 0%! Increase the Strength and Damping parameters until you start hearing something.

Try a nice pluck:

Parameter	Value
Shape	50%
Shift + Shape	30%
Strength	90%
Mallet	45%
Timbre	45%
Damping	70%
Brightness	45%

Issues

• The prologue Sound Librarian tends to timeout when transferring the user oscillator, however the transfer is still complete. Try adding the user oscillator one at a time and Send All / Receive All for each oscillator.

• There's been many reports that the Modal Resonator oscillator doesn't produce any sound. I've included a few versions which lower CPU usage which may yield better results. On my prologue there's been cases where I've had issues after a factory-reset where the oscillator wouldn't produce sound. Installing sequentially in the same oscillator slot the lightest CPU version osc_modal_strike_16_nolimit (16 filters and removed limiter), followed by osc_modal_strike_24_nolimit followed by osc_modal_strike resolved the issue for me. Your milage may vary.

• When first selecting the oscillator in the multi-engine, all values default to their minimum values, however the display seems to default to 0. For bipolar values it means the display might still show 0% while internally in the oscillator the value is -100%.

Building

• Checkout the repo (including subrepos)
• Follow the toolchain installation instructions in the logue-sdk
• Make sure you have the jq tool installed (brew install jq)
• Build with make

(only tested on MacOSX)

Acknowledgements

All credit to Emilie Gillet for her amazing modules!