User Manual

doepfer

System A - 100

VCF 4 A-123

3. Controls

1 Lev.

Use this attenuator to control the amount of signal

entering the filter input

If the filter’s output sounds distorted, turn this

control down, unless you deliberately want

the sound as a special effect.

2 Freq.

With this control you adjust the Cut-Off Frequency f

below which the filter attenuates all frequencies.

At zero, the filter is fully open. The more you turn the

filter up, the more the low frequencies are filtered (see

Fig. 1): the sound becomes thinner and less solid, until

at 10 the filter is completely shut, and blocks off all

frequencies below 15kHz. Frequencies above 15kHz

are still let through, but are generally outside normal

adult hearing range.

3 FCV

For voltage control or modulation of the cut-off fre-

quency using CV input § (see Fig. 1), use attenuator

to control the level of voltage control.

Fig. 1: White noise put through a high pass filter

4 QCV

Attenuator

gives you control over the level of vol-

tage control

applied to resonance.

Res.

With this control you adjust the filter’s resonance (or

‘emphasis’) - the parameter which emphasises the

frequencies around the cut-off point f

(see Fig. 2). It

strengthens or emphasises the band of frequencies

around the filter’s cut-off point.

OutOut

Freq.Freq.