Operation Manual

28 Parameters
The Hit Position controls where the excitation signal is applied on a resonator. This is an im-
portant parameter as it affects the relative amplitude of the different partials of the resonator and
therefore the spectrum of the sound it radiates as explained in Section 4.2.1. This position is indi-
cated as a percentage of the total size of the object. The minimum value of the control corresponds
to an excitation applied on the border of the object while the maximum value corresponds to an
excitation applied at its center. In the case where both resonators are coupled, the Hit Position set-
ting of resonator A represents the location where the excitation signal is applied while this setting
on resonator B represents the point where the extremity of Resonator A is coupled to resonator B.
As the tone of the resonator varies with the excitation position, it is interesting to modulate this
position while playing. This is possible using the Vel, Key controls which are used to adjust the
amount of modulation from the keyboard velocity, pitch signal respectively and the Rnd control
which applies a random modulation.
The Coupling selector is used to determine if the two resonators are coupled or not. In the Off
position, the resonators are not coupled and excited simultaneously. They are, in other words, in
a parallel configuration. The output signal is then a mix of the signals from the two resonators in
a proportion determined by the setting of the Balance slider. When in its center position, an equal
amount of signal from resonator A and B is present in the mix. More signal from resonator A or B
is obtained by adjusting the balance slider up or down.
The two resonators are coupled when the Coupling control is in the On position. In this case,
resonator A receives the excitation signal and energy is exchanged between the two resonators
through coupling which creates a new object whose characteristics depend on the parameters of
the two objects, the settings of the Hit Position controls as well as the ratio of the impedance of the
two objects.
In coupling mode, the Balance slider is used to adjust the impedance ratio, in other words how
easy it is to set one object into motion compared to the other. In the A position, the impedance
of resonator A is lower than that of resonator B implying that resonator B is very stiff compared
to resonator A. As a result, most of the energy is reflected back into a at the junction point and
resonator A is not much affected by resonator B; one mostly hears resonator A. Increasing this
parameter decreases the impedance of resonator B with respect to that of resonator A affecting
more and more the functioning of the first resonator. Below the center position, the impedance
of resonator B is lower than that of resonator A resulting in a change in the limit conditions of
resonator A and hence the frequency of its fundamental and partials depending on the settings of
resonator B. In other words, one starts to hear resonator B more and more in the final sound. The
amount of coupling or balance (in the case where they are in parallel mode) between the resonators,
can be modulated with the pitch of the note played with the Key control.
4.6 The Noise Envelope Module
This module is a simple ADSR envelope generator as illustrated in Figure 10. It is used to modulate
the Volume control of the Noise module as well as its Frequency and Density controls. The envelope