Operation Manual

SUBTRACTOR SYNTHESIZER
115
Filter 2
A very useful and unusual feature of the Subtractor Synthesizer is the presence of an
additional 12dB/Oct lowpass filter. Using two filters together can produce many inter-
esting filter characteristics, that would be impossible to create using a single filter, for
example formant effects.
The parameters are identical to Filter 1, except in that the filter type is fixed, and it
does not have filter keyboard tracking.
D To activate Filter 2, click the button at the top of the Filter 2 section.
Filter 1 and Filter 2 are connected in series. This means that the output of Filter 1
is routed to Filter 2, but both filters function independently. For example, if Filter 1
was filtering out most of the frequencies, this would leave Filter 2 very little to
“work with”. Similarly, if Filter 2 had a filter frequency setting of “0”, all frequencies
would be filtered out regardless of the settings of Filter 1.
✪ Try the “Singing Synth” patch (in the Monosynth category of the Factory
Sound Bank) for an example of how dual filters can be used.
Filter Link
When Link (and Filter 2) is activated, the Filter 1 frequency controls the frequency off-
set of Filter 2. That is, if you have set different filter frequency values for Filter 1 and 2,
changing the Filter 1 frequency will also change the frequency for Filter 2, but keeping
the relative offset.
✪ Try the “Fozzy Fonk” patch (in the Polysynth category of the Factory
Sound Bank) for an example how linked filters can be used.
! Caution! If no filter modulation is used, and the filters are linked, pulling
down the frequency of Filter 2 to zero will cause both filters to be set to
the same frequency. If combined with high Res settings, this can produce
very loud volume levels that cause distortion!
Envelopes - General
Envelope generators are used to control several important sound parameters in ana-
log synthesizers, such as pitch, volume, filter frequency etc. Envelopes govern how
these parameters should respond over time - from the moment a note is struck to the
moment it is released.
Standard synthesizer envelope generators have four parameters; Attack, Decay, Sus-
tain and Release (ADSR).
There are three envelope generators in the Subtractor, one for volume, one for the Fil-
ter 1 frequency, and one modulation envelope which has selectable modulation desti-
nations.
The ADSR envelope parameters.
Attack
When you play a note on your keyboard, the envelope is triggered. This means it
starts rising from zero to the maximum value. How long this should take, depends on
the Attack setting. If the Attack is set to “0”, the maximum value is reached instantly. If
this value is raised, it will take time before the maximum value is reached.
For example, if the Attack value is raised and the envelope is controlling the filter fre-
quency, the filter frequency will gradually rise up to a point each time a key is pressed,
like an “auto-wha” effect.
Decay
After the maximum value has been reached, the value starts to drop. How long this
should take is governed by the Decay parameter.
If you wanted to emulate the volume envelope of a note played on a piano for example,
the Attack should be set to “0” and the Decay parameter should be set to a medium
value, so that the volume gradually decreases down to silence, even if you keep hold-
ing the key down. Should you want the decay to drop to some other value than zero,
you use the Sustain parameter.
Attack
(time)
Decay
(time)
Sustain
(level)
Release
(time)
Key Down
Key Up
Level
Time