Audio Damage Basic - Manual (Page 9)

Filters: ! !
Basic has two filters, in a configuration known as “cascaded” or “series.” This means that the mixed signal from the oscillators passes
through Filter 1, and then through Filter 2. Nominally, when one sees a cascaded filter design like this in “the real world,” for example
on the Korg MS20, the filters are fixed states. In the MS20, the first filter is a highpass topology, meaning that it attenuates low
frequencies, while the second filter is a lowpass that attenuates high frequencies. The two together form, for all intents and purposes,
a bandpass filter with a whole lot of knobs. !
!
Since it was no particular trouble to make both of these filters state-variable (that is, each one can be lowpass, bandpass, or
highpass) that is what we’ve done. You can recreate the MS20 filter sound fairly easily by putting the first filter in “HPF” mode and the
second one in “LPF” mode, if you would like.!
!
The filter controls are common to almost all subtractive synths, and are fairly easy to
understand. !
!
1.Frequency: This controls the corner frequency of the filter.
2. Res: This is the resonance or emphasis of the corner frequency, also known as the “peak.”
The filters in Basic can self-resonate; when this control is set to higher values, from about 3
o’clock on, you’ll start to hear a tone at the frequency set by the Frequency control. Due to
the design of the filters in Basic, you’ll also begin to hear noticeable distortion in the signal.
3. Mod Source: These three controls set the amount of modulation added to the Frequency
control. The first adds modulation from the LFO. The second from the Filter Envelope, and
the third from MIDI velocity (how hard you hit the key on your controller, essentially.)
4. Topology: Each filter can be set to LPF (lowpass), BPF (bandpass), or HPF (highpass).!
!
!
The mod values in the filters are additive. That means that any modulation value is added to the filter frequency. For the envelope
and velocity, this should be fairly obvious. If your Frequency control is already on the high side, you won’t be able to add anything to it
with the envelope or velocity and hear the result in a meaningful way (although it may amuse your dog, if you have one.) For these
values to be effective, the Frequency control needs to be towards the anti-clockwise settings. !
!