FM Synthesis – Simon Hutchinson

4 April 2022

Making a Bad Sine Wave in Pure Data Vanilla

Building a “wab-sabi” oscillator in Pd to celebrate the beauty of imperfection and impermanence.

Sine waves are great! The perfection of a pure, single frequency can be both expressively and technically very useful in pursuing our musical goals. There are, however, lots of musical reasons that we might want to intentionally make our oscillators a little more rough around the edges.

Performance on traditional, acoustic instruments, of course, produces a huge amount of micro-variation across each note, and so it can be expressively engaging for us to be able to introduce that same imperfection (analog warmth?) in our digital instruments as well.

In this video, I build a bad sine wave by frequency-modulating my oscillator with noise, and then feeding back the output back into the modulation. While I build this out in Pure Data, the same can be done in Reaktor, Kyma, Max/MSP or any other synthesis environment.

More Pd Tutorials here.
No-talking Pure Data jams and patch-from-scratch.

0:00 Introduction, The Beauty of Imperfection
1:26 Slider-Controlled Sine Wave
3:28 Adding Noise
4:35 Frequency Modulating with Noise
7:24 Filtering the Noise
8:20 Feeding Back into FM
9:55 I’ve gone too far
13:26 Reaktor Examples
14:18 Closing Thoughts, Next Steps

10 January 2022

Basic FM Synthesis in Reaktor 6 Primary

Building a basic but expandable FM synthesizer in Reaktor 6, making an FM operators that we can duplicate as much as we want.

In FM synthesis, we modulate the frequency of one oscillator (the carrier) with another oscillator in the audible range. We can make an FM synth in Reaktor that’s modular and quickly expandable if we make a macro with the oscillator, an envelope, and a few special controls at the FM input.

0:00 Intro / What is FM Synthesis?
1:30 Sine Oscillator with Amplitude Envelope
3:14 The “F” Input of Sine FM Oscillators
4:20 Modulating the Frequency
5:24 Modulating the Frequency in the Audible Range
6:13 Adding Musical Controls
11:50 Combining Our FM Operators
13:01 Sideband Modulation with Envelope Control
16:12 Chaining FM Operators Together
19:48 Recap / Next Steps

Pure Data Patch from Scratch: Simple FM Synthesis Sequencer

A quick and easy Pure Data patch-from-scratch tutorial building a sequencer that plays dynamically changing timbres for each note though frequency modulation synthesis.

In this patch, we set up a simple sequence of sine wave pitches (frequencies), then a sequence of modulation frequencies of a different length, then a random patterns of deviations, creating a constantly changing series of sounds.

There’s no talking on this one, just building the patch, and listening to it go.

0:00 Sequencing the pitch of a sine wave
1:23 Creating modulation oscillator sequence
2:45 Randomizing the deviation
3:15 Audio math: modulator frequency
3:51 Audio math: deviation
4:09 Audio math: FM synthesis
4:31 Tweaking the numbers
4:52 Commenting the code
5:47 Adding delay (as usual)
6:55 Feedback for the delay
7:17 Listening and more tweaking numbers

More no-talking Pure Data jams and patch-from-scratch videos here: