When using Oscillator Sync, it can be very useful to have the
Shape amount(s) modulated from any of the Morph assign
sources, or by the Modulation Envelope. This will generate a signal
with continuously varied harmonic content.
Frequency Modulation
The basic principle behind frequency modulation (FM) synthesis is to
have one oscillator (the modulator) modulating the frequency of another
(the carrier) . The carrier can in turn modulate the frequency of yet
another oscillator, etc . There are several different algorithms in the FM
category ranging from one up to three oscillators (operators) modulat-
ing each other in series, with or without feedback on the first operator
in the chain .
The image above shows a 2 Operator FM-Synthesis setup, and the
resulting waveform using a fairly high FM amount setting .
The resulting waveform is far more rich in harmonics than the original
Sine waveform, and drastic changes in tonal character are provided by
altering the amount of modulation .
Modulator
There are several FM algorithms available; set-ups with various number
of oscillators, feedback and frequency ratio settings between the oscil-
Shape1
lators .
(FM Amount)
• Use the Waveform-dial to select the FM-algorithm .
• The Shape parameter is used for setting the amount of modulation
and/or feedback from none to maximum .
Carrier
There are three main FM algorithms in the Nord Stage 2: one, two
OSC MOD
and three oscillator FM with feedback . The feedback is not active in all
algorithms .
The Shape knob controls the FM and feedback amounts . When you
turn the knob, all modulations are increased simultaneously . The
number of harmonics, and their intensity, increase proportionally to the
FM amount . As usual, the Shape parameter can be modulated by the
Modulation Envelope or the LFO, and it can be Morph controlled by
any combination of wheel, aftertouch and pedal .
Modulator
Shape2
(FM Amount)
Carrier
OSC MIX
Shape
(Feedback)
Each algorithm comes with a number of pre-configured frequency
ratios . Depending on what kind of sound you want, choose from the
different combinations available and you have many interesting FM
sounds at your disposal . When a new algorithm is selected, the Main
display shows, for a short duration, the algorithm together with infor-
mation on the frequency relations between the operators and whether
feedback is used . The display shows the modulator(s) frequency
relation to the carrier . If an operator uses feedback, it is indicated by a
dot next to the digit . In the chart below all available algorithms together
with the notation used in the display are listed:
FM Algorithms
LED LCD
Description (FB = feedback)
Sin
1-OP (+FB)
Carrier only, with feedback
1 1
2-OP 1:1
Carrier + Modulator, same frequency
2 1
2-OP 2:1
Carrier + Modulator, frequency ratio 2:1
3 1
2-OP 3:1
Carrier + Modulator, frequency ratio 3:1
4 1
2-OP 4:1
Carrier + Modulator, frequency ratio 4:1
5 1
2-OP 5:1
Carrier + Modulator, frequency ratio 5:1
6 1
2-OP 6:1
Carrier + Modulator, frequency ratio 6:1
7 1
2-OP 7:1
Carrier + Modulator, frequency ratio 7:1
8 1
2-OP 8:1
Carrier + Modulator, frequency ratio 8:1
91
2-OP 9:1
Carrier + Modulator, frequency ratio 9:1
1 .1
2-OP 1:1 (+FB)
Carrier + Mod + FB, same frequency
2 .1
2-OP 2:1 (+FB)
Carrier + Mod + FB, frequency ratio 2:1
3 .1
2-OP 3:1 (+FB)
Carrier + Mod + FB, frequency ratio 3:1
4 .1
2-OP 4:1 (+FB)
Carrier + Mod + FB, frequency ratio 4:1
5 .1
2-OP 5:1 (+FB)
Carrier + Modulator, frequency ratio 5:1
6 .1
2-OP 6:1 (+FB)
Carrier + Mod + FB, frequency ratio 6:1
7 .1
2-OP 7:1 (+FB)
Carrier + Mod + FB, frequency ratio 7:1
8 .1
2-OP 8:1 (+FB)
Carrier + Mod + FB, frequency ratio 8:1
9 .1
2-OP 9:1 (+FB)
Carrier + Mod + FB, frequency ratio 9:1
9 .1
2-OP 9:1 (+FB)
Carrier + Mod + FB, frequency ratio 9:1
111
3-OP 1:1:1
Carrier + Mod + FB, same frequencies
211
3-OP 2:1:1
Carrier + Modulators, frequency ratios 2:1:1
311
3-OP 3:1:1
Carrier + Modulators, frequency ratios 3:1:1
511
3-OP 5:1:1
Carrier + Modulators, frequency ratios 5:1:1
911
3-OP 9:1:1
Carrier + Modulators, frequency ratios 9:1:1
221
3-OP 2:2:1
Carrier + Modulators, frequency ratios 2:2:1
421
3-OP 4:2:1
Carrier + Modulators, frequency ratios 4:2:1
821
3-OP 8:2:1
Carrier + Modulators, frequency ratios 8:2:1
1 .11
3-OP 1:1:1(+FB)
Carrier + Mod + FB, same frequencies
1 .21
3-OP 1:2:1(+FB)
Carrier + Mod + FB, freq . ratios 1:2:1
1 .31
3-OP 1:3:1(+FB)
Carrier + Mod + FB, freq . ratios 1:3:1
1 .51
3-OP 1:5:1(+FB)
Carrier + Mod + FB, freq . ratios 1:5:1
1 .91
3-OP 1:9:1(+FB)
Carrier + Mod + FB, freq . ratios 1:9:1
1 .F2
3-OP 1:1:2(+FB)
Carrier + Mod + FB, freq . ratios 1:1:2
2 .F2
3-OP 2:1:1(+FB)
Carrier + Mod + FB, freq . ratios 2:1:2
3 .F2
3-OP 3:1:2(+FB)
Carrier + Mod + FB, freq . ratios 3:1:2
5 .F2
3-OP 5:1:2(+FB)
Carrier + Mod + FB, freq . ratios 5:1:2
9 .F2
3-OP 9:1:2(+FB)
Carrier + Mod + FB, freq . ratios 9:1:2
Tip! The one-operator algorithm can be used to produce a perfect
sine-wave, if the Shape knob is set to zero.
Chapter8SyNth
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