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14. MORE ON OSCILLATORS, FILTERS, AND ENVELOPES
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14. MORE ON OSCILLATORS, FILTERS, AND ENVELOPES
In this chapter, the functionality of the oscillators, filters, and envelopes will be explained in further detail.
14.1 OSCILLATORS
Several waveforms are available to the two oscillators of each synth track. By adjusting the PW parameter,
the waveshape can be changed on all types of waveforms, changing their timbre. Furthermore, each oscilla-
tor has a dedicated PWM LFO, giving animation to the sound using pulse-width modulation.
SAW
This waveform has a biting, buzzy and distinct sound. It contains all harmonics, both odd and even, of the
fundamental frequency. Classic synth basses, strings, and brass sounds are often created using sawtooth
waveforms. The PW parameter brings in a second sawtooth, out of phase with the first one. Changing the
PW value or engaging PWM varies the phase difference between the two, similar to having two slightly
detuned oscillators running. This is useful to get a thicker sawtooth sound with more movement as differ-
ent harmonics interfere with each other. To get a regular single sawtooth, set PW to mid position or either
extreme value.
TRANSISTOR PULSE
Transistor pulse is special sort of pulse waveform, suitable when you want to achieve acid-like sounds. It
sounds a bit more shrill compared to the regular pulse waveform available to the oscillators. PW sets the
width of the upper and lower parts of the wave, just like on the regular pulse waveform described below.
The major difference is that one part of the transistor pulse waveform is not flat, but rather sloping a bit,
thus displaying a slightly similar form as a sawtooth waveform. This introduces more even harmonics, mak-
ing the sound less hollow. Extreme PW settings, positive or negative, will mute the waveform as the upper
or lower part disappears completely. A change in pitch also changes the waveform and pulse-width a bit,
giving slightly different sound at different pitches.
PULSE
When the PW parameter is set to its middle value of 0, a square wave will be produced. A square wave
contains only odd-numbered harmonics of the fundamental frequency and has a hollow sound, not quite
as full as a sawtooth waveform. Changing the PW makes the pulse waveform asymmetric, introducing even
harmonics and making the sound thinner and more nasal. Using PWM is the most classic way of adding
animation to a synthesizer waveform. When you want to recreate the sounds of old video games, square
waves are very handy. Extreme PW settings, positive or negative, will mute the waveform, as the upper or
lower part disappears completely.
TRIANGLE
A triangle waveform has a mellow and dampened sound, reminiscent of a mix between a pure sine wave
and a square wave. A triangle wave contains only odd-numbered harmonics, but at lower levels than a
square wave. A low-pass filtered triangle wave will sound very much like a sine wave. The PW parameter
introduces an edge in the waveform, gradually changing it from a pure triangle at mid position to a reversed
sawtooth waveform at extreme PW settings.
14.1.1 SUB OSCILLATORS
Each oscillator features a sub oscillator, running at a fixed interval below the oscillator. By activating a
sub oscillator, more depth and body will be added to the sound. The sub oscillators work as an extension
of the regular oscillator pitch, but will however not be affected by neither waveshaping nor pulse width
modulation. Four sub oscillator waveforms exist.
1OCT This option will add a square waveform one octave below the root note. The sub oscillator fre-
quency is 1/2 of the oscillator frequency.
2OCT This option will add a square waveform two octaves below the root note. The sub oscillator
frequency is 1/4 of the oscillator frequency.
2PUL This option will add a 25% pulse waveform two octaves below the root note. This selection
sounds a bit similar to mixing the 1OCT and 2OCT types.
5TH This option adds a 33% pulse waveform one perfect fifth, which is equivalent to seven semitones,
below the oscillator. The sub oscillator thus operates at 2/3 of the oscillator frequency. If for instance,
the oscillator plays a G, then the sub oscillator will play the C below it. Together with the other oscilla-
tor, this makes it possible to play a simple chord using just one track of the Analog Four MKII.