Glide (Portamento)

1. Rate Knob Sets the glide time.
2. Const/Prop Knob Selects between constant-time and proportional-time glide.
3. Active Input Module is active when input is high (10V) and inactive when input is low (0V). Always active when not connected. Current state is shown by LED.
4. Reset Input When Reset is triggered, the output immediately jumps to the input voltage.
5. Glide Input CV signal input. Usually a pitch signal.
6. Glide Output CV signal output.

Overview ⚓︎

The Glide module limits the rate of change of a control voltage, much like the Slew Limiter module. It is calibrated to work well with the Pitch output from the Keyboard or from a sequencer, resulting in a glide effect between consecutive notes. This is sometimes called a portamento.

This module works at CV rate.

Basic usage consists in connecting a pitch signal into the In jack, connecting the Out jack into the 1V/octave pitch input of a VCO or any other kind of audio signal generator, and adjusting the Rate and Const/Prop knobs to taste.

In Depth ⚓︎

Rate ⚓︎

The Rate knob controls the glide time, in seconds.

In constant time mode (Const/Prop knob fully counterclockwise), this is the time to reach a new input voltage from the current output voltage¹.

In proportional time mode (Const/Prop knob fully clockwise), the time to reach the new pitch depends on the difference in voltage between the output and the input. The value of the Rate knob represents the time it takes to increment or decrement the output by 1V. If the Glide module is used for a portamento effect, this is the time to glide over 1 octave.

Const/Prop ⚓︎

The Const/Prop knob select between constant-time and proportional-time glide, as described in the previous section.

Constant-time glide (knob fully counterclockwise) is implemented as an exponential curve. When used for a portamento effect, this is sometimes called exponential portamento. It starts quickly towards the target voltage and slows down as it gets closer.

Proportional-time glide (knob fully clockwise) uses a linear, constant-rate slope. When used for a portamento effect, this is sometimes called a linear portamento. Since the rate of change is constant, it takes more time to glide between values that are further apart than between close values.

The Const/Prop knob also allows in-between curves. This is convenient because an exponential portamento can often feel imprecise when playing short intervals quickly, and a linear portamento can be too slow when playing multi-octave intervals.

Active ⚓︎

When the incoming gate signal on the Active input is low (0V), the module is inactive and the signal on the In jack is routed directly to the Out jack. When the gate is high (10V), the module is active.

When the Active jack is not connected, it is normalled to 10V, which ensures that the module is always active.

This is meant to be connected to a sequencer’s Gate output to enable portamento only on chosen steps.

Reset ⚓︎

When the Reset input is triggered, the output will immediately be set to the input voltage, bypassing the glide algorithm.

Resetting is a one-time event that happens when the input goes from low to high (0V to 10V). Keeping the input high does not prevent future glides.

If the module is used for a portamento effect, a so-called legato portamento can be achieved by connecting the Keyboard’s Gate output into the Reset input. When the first note is played, there will be no portamento because the Glide module will be reset by the gate. However, if the second note is played before the first one is released, the gate will remain high and the module will not be reset, so the pitch will glide to the second note.