DiY/Noize #3

Playing catch-up here, so a quick note about a development from the previous experiment – and the first one that I consider to be a properly usable instrument.

dr1.b is a drone-synth based on the ATTINY85 as might be expected (I believe that tight space/speed constraints make for more interesting creative steps!). There are four controls:

  1. Pitch 1 (aka sync pitch): controls the basic pitch of the oscillator by resetting the oscillator at a regular period (i.e. hard sync);
  2. Pitch 2: controls the frequency of the actual waveform generator, it can generally be thought of as controlling the upper harmonics of the output sound. This can make some nice formant-like sounds;
  3. Waveshape: selects between Sine, Triangle, Square and Saw waveshapes, with intermediate settings between each pair (so that we get four compound waveshapes as well as the basic waves, i.e. sin+tri, tri+squ, squ+saw and saw+sin);
  4. Perturbation:  introduces a random switching of waveshape (the more you add, the more often the waveshape will change).

Output is 8 bit PWM running at 250kHz, with an underlying sample rate of 50kHz, theoretically allowing output of frequencies up to 25kHz, but that would need a far more accomplished reconstruction filter than the simple RC LPF which is in place!

dr1.a was put together on perfboard the day before the Orlando Ferguson show on December 17th at Chapel FM in Leeds – the results of which can be seen below (along with a MFOS ‘WSG’, a cracklbox and Ash’s 40106-based construction):

(dr1.a is the thing with four knobs on, just peeking out from behind the coffee cup).

code can be found on github here