Doepfer A-130/A-131 VCA (linear / logarithmic) - Manual (Page 3)

doepfer System A - 100 VCA A-130 / A-131
3
3. Controls
The A-130 has a linear response: the amplification is in
direct linear proportion to the control voltage input (see
Fig. 1).
The A-131 has an exponential (or logarithmic) re-
sponse. That means that control voltage changes have
less effect at low levels of amplification than at high
levels, and makes the A-131 more sensitive and sui-
table for subtle changes at low levels (see Fig. 1).
Fig. 1: Response curves for the A-130 and A-131
1 Gain
This controls the overall gain of the VCA.
At "0", with no control voltage present, there is no
amplification at all: no signal is present at the VCA’s
output. Once the gain control is turned up, amplification
occurs, even if there is no CV input present. The gain
control shifts the whole VCA response upwards (see
Fig. 2).
Fig. 2: Effect of gain control on VCA response
Control Voltage и и
10
5
0
5 10
lin.
exp.
Gain = 3
Control Voltage и и
10
5
0
5 10
lin.
exp.