128 EDIT PROGRAM
USING THE FILTERS AND ENVELOPE GENERATORS
One of the inherent problems of sampling is that, because of memory
limitations, it is usually necessary to loop a sample. This often has the effect
of reducing (or even removing!) the sound's natural dynamics making the
sample more like a snapshot than a movie.
To overcome this, however, we can use the filters and the envelope generators
to restore some of those attributes.
By bringing the filter 1 cutoff frequency down and using note-on velocity as a
controller, you can emulate the characteristics of most, if not all acoustic
sounds where loud notes are brighter in tone than quiet ones. Controlling the
output of ENV2 or ENV3 using velocity and applying that to the filter is
another way of doing this. Furthermore, another natural property of sound is
that during a note, the tonal quality changes. We can use envelopes and low
frequency oscillators to restore some of those qualities. Usually, the filter
will use the multi-stage ENV2 or ENV3 as its controller because tonal
changes are usually more complex than amplitude changes in acoustic sounds.
This envelope can also be used to imitate such things as brass growls - to
actually sample a brass growl would not only take up memory but would speed
up and slow down as you play it across the keyboard. ENV2 or ENV3 could be
applied to an ordinary brass sample and set so that Rate 3 swells back up
from a low Level 2 to not only recreate this effect but also to keep the swell at
a constant rate across the keyboard. Pressure may also be used for the same
effect although you would be controlling the growl - this may be preferable to
the 'automated' quality a preset envelope rate would have.
The second bank of filters allow even more extreme tonal processing to take
place. These filters may be used in conjunction with the filter 1 simply to
'clean' up the sound, removing unwanted artefacts from the sound. They may
also be used very creatively.
For example, the highpass filter may be used to more accurately replicate the
thin tone of an oboe or harpsichord as could the bandpass filter. Using two
lowpass filters in series allows you to create a notch filter to remove mid
frequencies. If resonance is applied to both lowpass filters, you may set two
resonant peaks. This can be useful in re-creating certain sounds that actually
have more than one resonant peak. You could try assigning, say, Env 2 to
modulate both. By setting one filter to have a positive going modulation and
the other to have negative going modulation, you can create some interesting
tonal variation during the course of a note - in fact, careful control in this
way can yield some very haunting vocal articulation effects.
Of course, you can combine low and high or band pass filters and, when you
apply modulation, some truly bizarre effects are possible. With so many
permutations, it is impossible to be give specific guidelines. The trick is
experimentation!
Of course, once you are in the realm of sampling synth waveforms and
processing them through the filters, you are in different territory but
anyone who has used an analogue synth will feel instantly at home with the
S3200's filter and envelope section. The only difference here, however, is
that instead of relying on a handful of waveforms, any sampled sound may be
used as the source. It is here that the modulation possibilities can be used to
good effect in the creation of new sounds (and the recreation of a few classic
old synth sounds too!)
Version 1.0 March 1993
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