Modulation

Modulation is a fundamental aspect of modular synthesis. Nearly all parameter knobs on Multiphonics modules have modulation inputs that react swiftly to incoming signals and that can withstand deep and quick modulation without unwanted artifacts.

Modulation inputs are easily recognizable as the unlabeled jacks with small attenuverter knobs located near parameter knobs. The following image shows different possible layouts for modulation inputs (highlighted in yellow).

Think of modulation as a way to turn a knob automatically. When a CV signal is applied to a modulation input, the effect will be the same as if you turned the knob by an amount proportional to the signal’s amplitude.

The small attenuverter knob next to the modulation input jack controls the modulation depth. The effect of the modulation is inverted if the modulation depth is negative.

The following video shows that modulating the Cutoff parameter on a µLP with an ADSR has the same effect as turning the Cutoff knob with the mouse.

Modulation Range ⚓︎

As a rule of the thumb, when the modulation depth is at 100%, then a modulation signal with a 10V range will cover the parameter knob’s range. For example, in the previous video, the Cutoff knob is fully counterclockwise, the modulation depth is at 100%, and the modulation signal from the ADSR goes from 0V to 10V. This has the same effect as turning the Cutoff knob fully clockwise.

Likewise, setting a parameter knob to its middle position and applying a bipolar modulation signal, such as the output of an LFO, will also cover the whole range of the knob.

This rule may not always be exact, but we followed it whenever possible while we were designing the module library to ensure a consistent patching experience.

Modulation Bounds ⚓︎

When a deep modulation is applied, it might go beyond the parameter knob’s range. Depending on the type of parameter, Multiphonics can handle this situation in three different ways.

Unbounded Modulation ⚓︎

For some parameters, it is possible for a modulation signal to make the internal parameter value go beyond the knob’s minimum or maximum values. For example, the Cutoff knob on the State Variable Filter module has a minimum value of 16 Hz, but it’s possible to go below that frequency with a deep negative modulation.

Clipped Modulation ⚓︎

Some parameters have hard limits that can’t be crossed. For example, the Noise Density can’t go above 100%, and the Mix 5 input volume can’t go below 0% (-∞dB). In those cases, applying a deeper modulation will have no effect.

Folding Modulation ⚓︎

Instead of clipping, some parameters have an innovative way to handle modulations that go beyond the parameter’s limit: when the limit is reached, the effect of the modulation signal folds back, so it sounds as if the modulated parameter had bounced on the limit and started going the other way. We call this a folding modulation.

For example, if you center the Compact VCO Sub FM knob and apply a slow rising envelope with a modulation depth of 100%, you will hear the FM effect increasing up to the maximum, and then decreasing even though the envelope is still rising.

This behavior only applies to a few chosen parameters to ensure that modulation signals always have an effect no matter what kind of modulation is applied, and no matter what the parameter knob position is.