Folium is a morphing microtonal FM synthesizer that listens to your scale and adjusts accordingly. Load a scale and its intervals become the oscillator's ratios and the filters resonance peaks. Morph between two patches with a crossfader, sequence parameters using the Motion Sequencer, and explore new sonic territories.
The idea for Folium started with a late night thought: most synthesizers treat a scale as a pitch chart.
What if a synth treated it as a material?
What if when I loaded up a tuning, the whole instrument adjusted to it, past its pitch?
One carrier, one modulator. The ratio between them is the sound, and in Folium it comes straight from your tuning. Load a scale over MTS-ESP or from a Scala file, pick up to eight intervals, and the ratio slider steps through them. 3:2 rings like a bell. 16:9 turns metallic.
The carrier comes in three waves.
SINE is the classic, pure FM carrier.
WARP pulls symmetry off-center for a warm, even-harmonic lean.
CARRIER builds the wave out of your scale's own degrees, so a new tuning is a new waveform.
Then it hits the folder.
West Coast wavefolding, right under the oscillator. A filter takes harmonics away. A folder puts them where there weren't any.
FOLD runs 1 to 8. Even 1.5 shifts the character.
BIAS sets the symmetry. Centered gives odd harmonics only, hollow and clarinet-like. Push it off center and the even ones come in, fuller and more vocal, still in tune.
TYPE morphs fold shapes. Buchla blooms, Serge saturates, Lockhart adds a diode edge. The knob is continuous, and the shapes between the three are folders nobody built in hardware.
Two DAHDSR envelopes drawn as a single line. ENV 1 drives volume. ENV 2 modulates parameters.
Drag nodes to set timing, drag between them to bend curves, or sync stages to your DAW.
Three morphable modes.
Gate holds while you hold the key.
One-shot ignores note-off, so a short stab and a held note sound identical.
Loop retriggers after decay, and your drawn line becomes a custom LFO.
The mode control is continuous. A gated pad can crossfade into a looping sequence inside one patch.
The left half is twin LFOs. The right is the ratio garden: every interval in your scale, laid out as dots. Click up to eight and they become the steps on the ratio slider.
Seven controls take modulation: ratio, FM, color, fold, bias, and both cutoffs. Under each one sits a thin lane.
Drag across to set depth, drag backwards to invert.
Click the label to assign LFO 1, LFO 2, ENV 1, or ENV 2.
A live dot rides the lane at the modulator's exact position.
Every one of the seven ships with a source on it. LFO 1 takes ratio, FM, color, and cutoff A. LFO 2 takes fold, bias, and cutoff B.
Both LFOs live in the central display, ten shapes each. Breathe fills up slowly and lets go fast. Tide beats two sines against each other at an irrational ratio, so it never repeats.
Two serial filters per voice with four modes each. The cutoff knob reads in true frequency, so what you dial is what you hear.
Click the petal mark beside a cutoff knob to quantize that filter to your loaded tuning. The cutoff then lands only on partials of the note you played that belong to your scale, one filter per voice.
Push Resonance past 70% and the filter self-oscillates on that exact scale degree.
And there are two of them. Set both singing on the same scale, move them by hand or LFO, and Folium turns into a dual resonator, stacked harmonics that come entirely out of your tuning.
Two lanes, up to eight steps. They move the knobs, not the notes.
Lane 1 owns the ratio slider.
Lane 2 routes to FM depth, fold, either cutoff, or the morph fader.
Tie steps together to glide values like a 303. Under ratio lock, the glide steps between degrees of your scale and never lands between them.
Switch Lane 1 to ABSOLUTE and the lane takes the slider outright, writing a melody in your tuning's own degrees.
Point Lane 2 at Morph to animate the whole patch in time.
Five stacked sliders in signal order.
Set State A. Change whatever you like. Set State B. A single crossfader now morphs Folium between two complete patches.
Continuous parameters slide. Discrete settings (carrier wave, filter modes, envelope modes, routings) switch at the midpoint. Every position between A and B is a patch you never programmed. Fade it by hand, or point a motion lane at it.
Folium.
In Early Access for Mac - VST3 and CLAP.
From the Vessel Log