Doepfer A-100(~ 40 MB) - Manual (Page 346)

A-130 / A-131 VCA System A - 100 doepfer
6
The voltage control input A to the modulation depth
VCA can come from an ADSR, MIDI controller, etc..
Fig. 6: AM with voltage-controlled modulation depth
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
determined by the pitch of a note - what’s usually
called 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.
To produce the opposite effect (that is, inverse key-
board tracking, where lower sounds are more ampli-
fied than higher ones) patch a Voltage-Inverter A-175
in before VCA 2 (see Fig. 8).
Fig. 7: Keyboard tracking - the higher the pitch, the
louder the output
Fig. 8: Inverted keyboard tracking: the higher the
pitch, the less amplification.
VCO
LFO
A
CV
CV
VCA 1
VCA 3
VCA 2
VCO
mf p f
CV
Gate
VCA 1
CV1
VCA 2
ADSR
VCO
CV
Gate
VCA 1
CV2
VCA 2
ADSR
mf p f
A-175
Gain = 10