Shortwave patches are built from two key sections. First of these are the four Sine generators: one Fundamental and three Harmonics. These can be adjusted in pitch and level relative to each other, increasingly randomised using dedicated random LFOs, or locked to cyclic variations imparted by the Periodic Fluctuation generator, which acts as a master LFO across all the sines. The Fundamental can be distorted, giving it further triangle-wave-style overtones, and by carefully tuning the Harmonic waves, a crude approximation of different classic synth waves can be managed.

But to treat Shortwave as a conventional synth is to miss the fun part. The second section of its sound generation engine comprises the two Interference Generators. Each of these selects between 111 long, looped samples of “interference” – everything from basic hiss and noise, through periodic, cyclic effects, to tuning squeals and shrieks; voices, numbers stations, and Morse code signals; distorted carrier waves, strange atmospheric anomalies, and other tonal weirdnesses. These can be blended into the sound, and subjected to their own Randomisation controls, which randomly vary their amplitude independently of the Sines, fading them in and out of the range of hearing in a totally organic way. These long samples – usually between 20 and 30 seconds each – have randomised start points, so repeated notes will key the sample from a new point each time, adding further to the complexity and non-repeating character of the waveform.

The majority of the 111 Interference waveforms were recorded by us, in an attic, with a 60-foot antenna loop and a real-life shortwave receiver, over a series of long nights where we searched for the strangest things the airwaves had to offer us. We found genuine, functioning numbers stations, cranking out spy code in robotic voices with Russian accents; we stumbled through CB radio conversations and Marxist governmental propaganda; we heard voices from the far sides of the world. It was magical. Some of these samples are presented unaltered, and some were high-pass filtered to take out the rumble (look for the HPF note in their Interference Generator names). Then we also recorded a set of samples from our ever-growing modular synth, getting “pure” white and pink noise, and roping two Manhattan Analog MA-35 analogue filters together with two Doepfer random CV generators and making them fight it out. The resulting squeals, howls and groans are there for the taking too, though they’re labelled in green to distinguish them from the authentic radio waveforms, which are listed in black. (In the main screenshot above, there’s one genuine shortwave radio sample that’s been high-pass filtered loaded into Interference slot 1, and a modular version of static noise in slot 2.)