Applied Acoustics Systems Chromaphone 3 Upgrade Acoustic Object Synthesizer Plug-In (Download) - Manual (Page 45)

5.3 The Synth Section 45
The decay time of the partials of the object is determined by the Decay control. This parameter
can be modulated as a function of the note played on the keyboard and its MIDI velocity using the
Key and Vel modulation parameters respectively. Note that in the case of a Tube object, the decay
time of the sound is also affected by the Radius parameter. In that case, the total decay time will
be determined by the cumulative effect of the Decay and Radius parameters. Note that the decay
time of instruments with coupled resonators also depends on the amount of coupling.
The Rel parameter is used to simulate the effect of dampers on the object when a note is
released. The release time is calculated as a percentage of the total decay time of the object as
set by the
Decay parameter.
The Material control allows one to fix the decay time of partials as a function of frequency
with respect to that of the fundamental. This is a parameter characteristic of the material of the
object. When this parameter is set to a value of zero, all partials decay at the same rate, that fixed
by the position of the
Decay control. Adjusting the Material control to a negative value favors low
frequencies by decreasing more and more the decay time of partials as their frequency increases.
When this control is set to a value of -1, the decay time will be inversely proportional to the
frequency of the partial. Thus a partial with a frequency twice as great as that of the fundamental
will have a decay twice as short as that of the fundamental, a partial with a frequency three time as
great will have a decay time three times shorter and so on. Using a positive value for this parameter
has an opposite effect as the low partials then decay more rapidly than the higher ones. When this
parameter is set to a value of 1, the decay time is proportional to the frequency of the partial. For
example, the decay time of a partial with a frequency twice as great as that of the fundamental will
have a decay twice as long as that of the fundamental and so on.
The Tone control is used to adjust the amplitude of the partials as a function of frequency with
respect to that of the fundamental. When this control is adjusted to a value of zero, all partials have
the same amplitude. When this control is set to a negative value, the high partials have a smaller
amplitude than the low ones. For example, a value of -6dB/octave results in the amplitude of the
partials being inversely proportional to their frequency. Thus a partial having a frequency twice
as great as that of the fundamental will have an amplitude twice as small (-6 dB), a partial with a
frequency four times that of the frequency will have an amplitude 4 times smaller (-12 dB) and so
on. When this control has a positive value, the effect is inverted. The low frequency partials then
have a smaller amplitude than the higher ones. For example, when this parameter is set to a value
of +6 dB/octave, the amplitude of the partial is proportional to its frequency. Thus a partial with
a frequency twice that of the fundamental will have an amplitude twice as great (+6 dB) as that
of the fundamental and so on. Note that these amplitude values can further be modulated by the
excitation position (see
Hit Position control) which is a parameter affecting the relative amplitude
of the partials.
The Low Cut parameter gives additional control on the low frequency response of the resonator
by applying a -24 dB per octave low-cut filter. This control is useful when clearer sounds are de-
sired. The
Low Cut knob is used to adjust the cut-off frequency of the filter. In its leftmost position,
the low cut filter is inactive and the sound is not affected. Turning the knob clockwise displaces the
cut-off frequency towards higher frequencies following steps corresponding to harmonics numbers