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In all string instruments there is a mechanism to mute the sound from the instrument. In the piano, a felt is applied on the strings when keys are released. In guitars and violins, the performer mutes the strings with his/her fingers.These muting mechanisms are not totally quiet and always produce some noise which has to be considered as part of the timbre of the instrument.
In String Studio, the Damper module is used to reproduce this muting mechanism. The purpose of this article is to explain the effects of the parameters of this module and explain how various effects can be achieved. All the presets used to make the sound examples included in this article are available from the user library and follow the same numbering convention.
The damper is modeled with a mass, a dashpot and an elastic shell represented by a spring. On the graphical interface, the mass of the damper, the damping applied by the dashpot and the stiffness of the shell are controlled by the Mass, Damp and Stiff knobs.
The velocity of the mass of the damper when the damper falls on the string (key released) and when it leaves the string (key depressed) is controlled through the Velocity knob. Finally, the Gated switch controls when the damper is applied to the string. When it is in its On position, the damper is removed from the string when a key is depressed and it is applied on the string when the key is released. When the switch is in its Off position, the damper always remains on the string even when the key is released. Note that the mass, stiffness and velocity parameters can be scaled with the pitch signal from the keyboard.
It is possible to adjust the position of the damper on the string by using the corresponding Position knob on the Geometry module.
The mass parameter determines how hard the the shell of the damper will press on the string. When the mass is high, the oscillations from string are quickly muted because more energy is required to move the mass.
Reducing the mass of the damper makes it less efficient and the interaction between the damper and the string is longer.
The stiffness of the elastic shell is related to the material of the damper. For soft materials like felt, the stiffness is low while it is high for metal. When the stiffness is high, the damper is more likely to bounce on the string.
The dashpot is the device used to reproduce the absorption of the vibrating energy from the string by the damper and its behavior is controlled with the Damp knob. In its leftmost position, the damping is low which results in a long release time.
Turning the knob clockwise increases the damping and therefore reduces the release time.
Note that this simple behavior is consistent until the knob reaches its middle position but may seem counter intuitive when the damping is increased further. Indeed, when the dashpot becomes very stiff, it absorbs energy better but because it is not attached to the string it also starts bouncing as a result of the elasticity of the shell. This implies that the damper is not in contact with the string during a large portion of its motion and therefore can not absorb energy from the string anymore. This results in a bouncing motion which increases the overall decay time.
In all the preceding examples, the damper was gated (Gated switch in its On position). When the switch is in its Off position, the damper always remain on the string whether a key is depressed or released and one can achieve various effects.
In the following example, the damper is stiff and light and bounces on the string.
Increasing the mass of the damper results in a buzz, due to the fact that the damper then stays in closer contact with the string.
Increasing even further the mass of the damper and carefully choosing its position on the string (with the corresponding position knob on the Geometry module) one can allow for only a few harmonics of the string to play. This is the same effect as when a guitar player gently puts fingers from the right hand on the strings.
When the velocity of the damper is low, the string can hit the damper during the attack of a sound before the damper has been fully applied on the string. This produces a sound similar to a slap on a guitar (the string hits the fret during the attack).
Increasing the velocity will avoid the string/damper interaction during the attack phase of notes.
We will now review some presets which emphasis the use of the damper module.
In a lot of situation, the use of the damper can add a little something to the sound which will enhance its character by adding a little noise when notes are released. In the following examples, the damper is used to add a funky touch to the sound.
In this case, the damper makes a noise which recalls the noise of the strings on the frets of a guitar giving a more acoustic character to the sound.
These two presets demonstrate the use of a low velocity on the damper in order to create a slap effects for bass sounds and for leads.
In these two presets, the damper is used to produce harmonics as described earlier. In the first example, the damper is gated and leaves an harmonic tone ringing when the key is released.
In the second preset, the damper is not gated.
When the damper is not gated, it always remains on the string. This is very efficient to create ethnic sounds.
Used more gently, it can be used to add a subtle non-linear behavior as in this fretless bass sound.
Finally, getting the hammer to bounce on the strings can help to make sustained sound as in this pad example.
It is interesting to note that it is possible to mute the string when a key is released even without the help of the Damper module. A muting effect can be obtained by clicking on the Ratio LED and using the grey knob located under the Decay knob of the String module. This parameter determines the ratio between the decay time of the string oscillations when a key is depressed and when it is released. When the knob is in its leftmost position, the internal damping of the string is the same as that set by the Decay knob and the decay time is the same whether a key is depressed or released. When the knob is turned clockwise, the decay time of the string becomes shorter for key releases. In other words, the internal damping of the string is increased after a key is released.
This feature is handy when one does not want to use the Damper module (module switched Off) or to fine tune the release time when the Damper module is switched On because both damping effects then add up.