Tension: Control a String’s Excitation and Damping

A bright beginning can have a dark ending

Start with the plucked example. The original MIDI note pattern excites a modeled string; it is not a guitar recording. Exciter is Pluck, which injects a short noise burst into the loop. Exc Color filters that excitation. The starting 80% gives the loop a relatively bright initial disturbance.

Leave Exc Color unchanged and increase Damping from 25% toward 70%. Listen for the string becoming darker as energy circulates. The damping filter lives inside the feedback loop, so this is not simply a tone control applied once after the instrument. Return to 25%, then lower Exc Color instead. The second change gives the string a darker start rather than changing the same part of the signal path.

Decay sets the intended loss over time while the note is held. Damping introduces frequency-dependent loss as well, so a nominal three-second Decay does not promise that every partial remains equally audible for three seconds. Raise Decay if a lightly damped note disappears too soon; lower Damping if the problem is specifically that its upper detail vanishes.

The end of a note is a separate decision

Damper acts at note-off by adding loop loss. It is not another spelling of Damping. In the plucked example it is only 15%, allowing more of the string to remain after short notes. Increase it toward 80% and compare the sound against the visible note endings. If every note is short, strong Damper can dominate your impression of Decay.

Use this distinction when arranging: lower Damper suits separated plucks that may ring across a gap; stronger Damper helps stop earlier notes from blurring a fast passage. A long tail is not always more expressive. Check whether it carries useful harmony or merely joins together notes that should remain distinct.

Continuous excitation changes the experiment

The second example selects Bow and uses a melodic MIDI phrase. In this implementation Bow continuously injects filtered noise while a note is held. It is a sustained-excitation approximation, not a detailed friction model or a recording of a bowed string. Releasing the note stops the feed; Damper then determines how decisively the remaining loop energy is reduced.

Lower Bow Level from 45% to hear less continuous input, then restore it. Raising Decay can also increase persistence, but that retains energy rather than supplying more of it. If the result becomes too insistent, reduce Bow Level before assuming that a darker Damping setting is the only solution. Bow Level is not a second volume control for Pluck mode.

Listen at a different point on the string

Pickup changes a feedforward comb applied to the string output. Move it slowly and listen for particular harmonics weakening instead of expecting a uniform treble reduction. Near zero the extra pickup coloration is effectively off. It does not pan the note or move a microphone in a modeled room.

The bowed setting includes only 0.06 st of Vibrato. Compare it with zero, then change Vib Rate before increasing depth. Vibrato modulates the loop length and therefore pitch; it is not tremolo. Too much can hide whether the underlying note is stable, especially when the pickup emphasizes an unusual set of partials.

These controls describe an extended Karplus–Strong-style model: a fractional delay, filtering, excitation and loss. Treat instrument associations as creative starting points, not proof of acoustic realism. Set Transp for register and Volume for balance only after you understand which energy is entering, circulating and being removed.