We know using one oscillator to frequency modulate another is a lot of fun…but just what is the difference between the different types of FM? I finally got my hands on a module – the Endorphin.es Furthrrrr Generator complex oscillator – that is capable of being switched (with some behind-the-faceplate fiddling) between exponential, linear, and linear through zero FM, so this is a good opportunity to finally make an apples to apples to apples comparison between the three.
The AJH Synth Ring SM is three modules in one: a ring modulator based on an analog transistor core design, a sub bass generator that creates tones 1 and 2 octaves down, and a 5 input mixer based on the classic Moog CP-3 design. This mixer is used to combine the original inputs, ring modular, and sub bass sounds; you can override them by patching in alternate inputs. The bonus preview movie from the soon-to-be-released Eurorack Expansion course focuses on the ring modulator section, showing a few different applications as well as really focusing on the waveforms and harmonic spectra it creates so that you better understand how a ring modulator works:
The Sputnik Modular West Coast Random Source is a very capable Eurorack-format update on the classic Buchla Source of Uncertainty module. In this movie, I focus first on uses for those 1:2 switches, including using them to send alternating note-on gate or triggers to alternating drum sounds. Then I move on to showing the sample and hold itself, first with the typical “science fiction soundtrack” random pitch technique, and then for something more subtle such as randomly changing the pulse width.
A favorite “West Coast” module that synthesists of all tastes should check out is the LPG: the low-pass gate, which acts like a VCA but with a filter element that also dampens the high frequencies. A new “hybrid” application I’ve found LPGs to be useful for is to process the output of dedicated percussion modules. An LPG naturally damps both the amplitude and harmonics of the input to mold most sounds into a typical percussive shape, freeing you up to dial in the initial noise and harmonic mix you like without worrying about the original sound ringing out too long or taking up too much room frequency-wise in a mix.