Oberheim Matrix-12 - VCA Parameters

Examples of how different Low Pass Modes roll off harmonics are illustrated in the
diagram on the previous page. A1 POLE LOW PASS filter mode attenuates at a
rate of 6dB/Octave, resulting in a moderate "slope". Adding more Poles causes
the roll-off slope to be steeper, cutting off more harmonics: 2 POLE LOW PASS =
12dB/Octave, 3 POLE LOW PASS = 18dB/Octave and 4 POLE LOW PASS =
24dB/Octave.
In audible terms, using fewer Poles in the LOW PASS Modes results in a brighter
sound because more harmonics are passed through the VCF. Using more poles
results in a fatter or bassier sound because fewer harmonics are passed.
VCA Parameters
The VCA section in the MATRIX-12 is a 2-Stage function allowing for expanded
flexibilty in the volume articulation of the Patch. This section contains two
independent VoJtage Controlled Amplifiers labeled VCA1 and VCA2.
VCA 1 This first-stage VCA sets the initial output of the Patch.
Amount value range is 0 to 63 where 0 indicates no output
or silence and 63 is maximum output.
VCA 2 The second-stage VCA sets the final output of the Patch and
sends its signal to the AUDIO OUT of the MATRIX-12. VCA 1
and VCA 2 are connected in "series", meaning that the
output of VCA 1 goes to the input of VCA 2. The overall
volume level of the Patch depends on the Amount values of
these two parameters, in conjunction with the VOL output
settings of the two VCOs. Amount value range is like that of
VCA 1:0 to 63 where 0 indicates no output or silence and
63 is maximum output.
Why TivoVCAs?
Utilizing two Voltage Controlled Amplfiers in the MATRIX-12 Voice provides for
enormous flexibility not possible with only one. Modulation routings, especially
those employing the use of PRESSURE and VELOCITY, become more useful
when the tasks of initial and final output levels are shared by two VCAs.
As an example, VCAs in other synthesizers have generally been "invisible" - no
front panel control was present to permit the user to adjust its level or what was
modulating it. Its Amount was permanently set to 0, and was activated only by the
Volume Envelope hardwired to it.
In the MATRIX-12, any one of the 27 Modulation Sources can be assigned to the
VCAs for a myriad of effects not otherwise possible. Since each Destination in the
MATRIX-12 can be modulated by up to six Sources at the same time, you are
given 12 VCA modulations to work with at any given time - six for VCA 1 and six
for VCA 2.
Careful consideration must be given to what Source is selected to modulate each
VCA, the Amount of modulation, and the settings of the VCAs themselves. The
MATRIX-12 has a total of 15 VCAs strategically located throughout each Voice
used to set the output level for the various parameters. The two VCAs in the
VCF/VCA Page in particular are the ones through which the synthesizer's sound
Matrix-12 Owner's Manual 115