Operation Manual

6.12 Bowed Multimode 78
The Bowed Multimode module is not directly accessible to the user.
Rather, other modules such as Bowed String, Bowed Plate, Bowed Beam,
Bowed Marimba and Bowed Membrane use the Bowed Multimode mod-
ule as their front. These other modules first calculate the different modal
parameters corresponding to their respective structure type as requested at
construction and, next, call the Bowed Multimode module in order to im-
plement the parameters they require. Since these different object types are
based on the same underlying simulation technique, they all have the same
number of inputs and outputs and share the same controls (which appear on
their front panel) for changing their physical properties.
Amplitude
The amplitude control is simply a gain which controls the amplitude of the output signal. It can be
adjusted with the amp knob on the front panel.
Decay
The damping of an object affects the decay time of the sound produced by the object. This param-
eter is adjusted using the decay knob on the front panel. When the knob is turned left, the damping
is strong and the decay time short; damping is light and decay time is long when the knob is turned
right. The damping is characteristic of the material of the object. For example, damping in wood
is strong and the decay time is short (knob turned to left) and in steel damping is weaker and,
therefore, decay time is longer (knob turned to right). But damping also varies for a given material
depending on how the object is used or connected to other objects. The oscillation of a string, for
example, has a much shorter decay time when used on a violin than on a mandolin.
Playing frequency
The frequency of the sound produced by an object is dependent on its “useful” size. A large metal
plate, for example, produces a sound with a lower pitch than does a smaller one. The pitch of the
output of a Bowed Multimode object is determined by the signal entering the pitch input signal
appearing on every such object. In other words, the size of the object is varied in order to obtain
the requested pitch. The mod knob is a gain knob affecting the amplitude of the pitch input signal.
When in the center position (green LED on), the gain equals 1 and the pitch variation is equal to
1 Volt/octave. This position is used to play an equal temperament scale when connecting the note
output of a Keyboard to the pitch signal input of a Bowed Multimode object.
Force
The force knob is a gain knob acting on the force input of a Bowed Multimode object.