Microtonal VST Synths


These synths use the Scala 2 SynthEdit Microtuner to manage their tunings. They are CPU-light and multiple instances are easily supported in a typical VST host. Real-time key and/or tuning change can be triggered on reserved midi channels to control fully polyphonic tuning changes of multiple instances of the synths on other channels. Please follow the Scala 2 SynthEdit Microtuner menu link to learn more about their microtuning features.

These synths are offered as donationware for contributions to the World Wildlife Fund.


microHarmonic VST Synth

This is a four oscillator, phase modulation synth. Each oscillator can be independently pitched at an interval of the current tuning relative to the current note. Routing the oscillators in FM-style carrier/modulator arrangements with ratio-based offsets can produce bell/mallet/tine sounds that are less harsh than the typical FM synth.

microHarmonic Synth

The microHarmonic microtuned VST (click for more screen shots)

Click here or on the screenprint above to open an interactive guide to the microHarmonic synth.

The synth's features include:

The microHarmonic VST is provided in demo and full versions. The demo version has a session time limit.

Here is a demo clip of the microHarmonic synth. /> microHarmonicDemo.mp3 This is in the 19 tone 9-limit tonality diamond, modulated on itself.

Additional Credits:

microGuitar VST Synth

microGuitar3 Waveguide Synth

The microGuitar Microtuned Waveguide VST

This is a versatile Karplus-Strong simulation of bright acoustic and bass guitars. It uses high quality interpolation and antialiasing for clarity, along with graphic profiles of key parameters to give detailed control of its sound.

Brief, sampled waveforms are used as impulses for the tuned waveguide. Several tone controls are provided for impulse shaping, bass boost, and loop decay. An additional waveguide simulates pick position, with controls for pick strength and cutoff. It has a bank of five graphically adjustable resonators in the 50 - 800 hz range to simulate body resonance.

Digital waveguides have an inherent issue with quantized pitch, so extra measures have been taken to ensure pitch accuracy within one hz across the intrument's range. A GUI panel exposes fine-tuning adjustments by semi-tone to compensate for complex phase response of the waveguide.

Additional controls cover the amplitude envelope of the guitar. Separate 'bright' and 'damp' profiles can be set for attack, initial damping by pitch, and release. Pitch-based damping can be drawn graphically with a mouse swipe for each of the profiles. A single parameter can be swept in real time to morph between the profiles and give a realistic 'strum' feel. Additional controls are provided to set the attack curve, and two stages of exponential decay. The synth has 15 voice polyphony to allow for extended, reverberant fades.

The instrument has an optional signal path for soft distortion plus feedback. Controls are provided covering feedback delay, lowpass filter, mix, and feedback strength. Distortion is created by a triple oversampled cubic waveshaper that provides electro-acoustic sustain and ambiance.

Additional features include

As with all synths offered here, the microGuitar has a popup screen to load Scala files and set microtuning parameters. Several microGuitars can be loaded independently on individual midi tracks. Midi notes played on a control track can then drive simultaneous ensemble key change or scale selection in microtonal scales across all tracks. Ensemble on-the-fly tuning change is rarely provided for in microtonal music, but is a potentially expansive addition to the art.

The demo version of the instrument plays for a few minutes per session and then plays in monotone. This VST is offered as registered charityware for a $5 USD donation to the World Wildlife Fund.

Here's a demo clip (1). microGuitar3Demo.mp3

(1) Modulated Ben Johnston 25 tone extended just intonation tuning. Three guitar instances (rhythm, lead, bass) with convolution reverb plus Kontakt vibes sequenced in Reaper on a multicore PC. One midi track controls key changes for both guitar and vibes.

microFlute VST Synth

This new version has several improvements to the waveguide that give it improved range and clarity. Also, pitch is now calibrated to offset acoustic impedance. This is comparable to embouchure adjustments a flute player makes to shade into correct pitch across the instrument range. In addition to flute range, this VST plays smooth bass all the way down to 16 hz. Here are a couple of demo tunes (flute + Kontakt 3.5):   microFlute2Demo.mp3 (14 tone superparticular)   microFlute2Demo2.mp3 (25 tone Ben Johnston extended just intonation).

microFlute3 Waveguide Synth microFlute3 Waveguide Synth

The microFlute Microtuned Waveguide VST

Tremelo is based on breath pressure, which works the whole model to give a more convincing effect than typical synth tremelo. Breath and percussive tongue envelopes add coloration to the tone harmonicly centered on the 3rd, 5th, and 7th overtones. The model includes a polyphonic legato phrasing option, so an adjustable brief pause can set whether the following note or chord will have breath and/or tongue articulation.

The flute has eight voice polyphony and 24 parameters addressable for for VST automation.

microVibes VST Synth

This synth combines the STK model of a resonant stiff bar with a sampler. Overtone vibration modes of a bar are modeled with four resonators (biquad filters). Resonance, gain and relative pitch of the resonators can be set with precision. Graphic control is provided to set the volume weighting of each mode across 10 velocity bands. The sampler portion supports microtuned, non-looped playback of a .wav sample. The resonant filters, envelope, vibrato, and sampler are calculated and cross-faded per sample in a single pass.

The basic idea is that the sampler gives an 'identity' timbre, and the resonators add velocity sensitive overtones to give additional tone colors. For concussive decay strikes of idiophone materials such as metal, glass, or wood, a single sample can reasonably cover about an octave, so multiple instances of the synth may be needed to cover an instrument's full range.

The synth provides standard Windows file navigation for selection of a sample, which is validated for compatibility before loading. All voicing parameters can be controlled by midi or VST host automation. The synth is provided with 12 voice polyphony and CPU consumption is generally low. Here is some additional usage documentation: microVibes .pdf.

microVibes Modal Resonance/Sampler VST Synth

The microVibes Modal Resonance/Sampler VST

The microVibes VST is provided as a full version with an installer .exe that adds a small directory with a few 'starter' samples. MicroVibes is free, although its Microtuner is time-limited until registered. Here's a clip of microVibes played in a 24 divisions of equal length scale*, modulated on itself. Scala2SE\microVibesDemo.mp3 Here's a higher quality .wma version.

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* Derived from 12 tones in the first 24 frequencies of the harmonic series. Click to toggle scala file.