Doepfer A-130/A-131 VCA (linear / logarithmic) - Manual (Page 7)

doepfer System A - 100 VCA A-130 / A-131
7
Keyboard control of VCA (tracking)
You can use the CV output from a keyboard to modu-
late the VCA, and so have level of amplification de-
termined by the pitch of a note - what’s usually cal-
led keyboard tracking.
In the example in Fig. 7, high frequency notes are
amplified more than low frequency notes. Use control 1
on VCA 2 to vary the degree of keyboard tracking.
Fig. 7: Keyboard tracking - the higher the pitch, the
louder the output
To produce the opposite effect (that is, inverse keyboard
tracking, where lower sounds are more amplified than
higher ones) patch a Voltage-Inverter A-175 in before
VCA 2 (see Fig. 8).
Set the gain control 1 at maximum, and use CV2
control 2 to determine the intensity of the effect
Fig. 8: Inverted keyboard tracking: the higher the
pitch, the less amplification.
VCO
mf p f
CV
Gat e
VCA 1
CV1
VCA 2
ADSR
VCO
CV
Gat e
VCA 1
CV2
VCA 2
ADSR
mf p f
A-175
Gain = 10