This is a reworking of a much-earlier synth. The original was monophonic and the reboot is polyphonic. It uses (slightly retro) phase modulation as its synthesis engine which allows a nice rich variety of sounds.

• polyphonic with 4 voices (4 notes can be played simultaneously)
• 2 x oscillators (timbres) per voice
• 8 x phase-modulation waveforms + combinations (36 in total)
• white noise
• 6 x ADSR (attack-decay-sustain-release) envelopes per voice
• 6 x LFOs (low-frequency oscillators) per voice
• 6 x LFO waveforms (sine, square, triangle, rising sawtooth, falling sawtooth, noise)
• detuned oscillators by semitones or cents
• connects to standard MIDI keyboards (velocity sensitive)
• keyboard transpose (up to +/– 2 octaves)
• keyboard split
• pitch bend and modulation
• ring modulator
• oscillator synch
• flanger (swept comb filter)
• portamento (constant rate and constant time)
• delay line (up to 150ms) with feedback and dry-wet mix
• selectable MIDI channel #1 to #16 or all channels
• 40 x preset patches
• 24 x user patches (non-volatile)
• master volume control
• Windows desktop app Patch Editor

The demos linked below (all recorded live) give a good idea of the variety of sounds that can be produced. The associated patches are stored in the firmware accessible via the pushbuttons on the PCB.

A patch editor is available as a Windows GUI desktop app. This allows editing of the existing patches as well as the creation of new patches. Typically the editor works in conjunction with a USB-to-MIDI adapter connected to the PC and the 5-pin DIN MIDI socket on Bleep-o-tron. (Note that the USB-to-MIDI adapter must be able to handle MIDI SysEx messages correctly for the patch editor to work - not all of them do.)

Supplied as a kit of PCB and components. All components are through-hole. Power input is via a 2.1mm DC power socket or battery snap, and audio output is mono through a 3.5mm jack socket.

Demos on SoundCloud