Clavia nord lead, Owner'S Manual

Page: 80 / 114

Page 78 About Subtractive Synthesis
In the first, the jump happens 5% in from the beginning of the period. This is referred to as a pulse wave
with a 5%
pulse width (sometimes called duty cycle ). The second wave has a pulse width of 10%. The
third wave has a pulse width of 50%.
This third wave is a special case of the pulse wave, called a square wave , and this has one peculiarity, it
only contains odd number harmonics, which gives it a “hollow” quality.
On many synthesizers (including the Nord Lead) the pulse width can be adjusted, to set the timbre of the
pulse wave. The more narrow the pulse width, the more “thin” the sound will be.
You can also have the pulse width vary continuously, for example from an LFO or envelope. This is re-
ferred to as
pulse width modulation . Modulating pulse widths from an LFO creates a rich, chorus-like
effect often used in “string” sounds.
About Inharmonic Spectra
Above we have only discussed spectra where the overtones appear at perfect harmonics. While this is
true for the basic waveforms discussed above, it is definitely not true for all sound. If you for example
use the frequency modulation (FM) capabilities in the Nord Lead, with the two oscillators set to an unu-
sual” interval (not octaves or fifths, for example), you will get a spectrum where the overtones appear at
frequencies somewhere
between the perfect harmonics. This results in an inharmonic sound, which of-
ten sounds “metallic”.
Sync
One some instruments (including the nord Lead), two Oscillators can be synchronized . If you for exam-
ple synchronize Oscillator 2 to Oscillator 1, Oscillator 2 will start over with a new period of the waveform,
each time Oscillator 1 does so. If Oscillator 2 then has a higher frequency than 1, it will get a complex
waveform that depends both on its own pitch and on that of the other oscillator.
Amplitude
Time
Amplitude
Harmonic number
(Frequency)
1 2 3 4 5 6 7 8
Oscillator 1
Oscillator 2
(synchronized)