MATRIXSYNTH: John Crombie

Published on Jan 17, 2019 John Crombie

This is the first Pulse Synthesizers branded post on the site.

John Crombie also brought us the eurorack granular synthesizer & 4 channel USB sampler.

"Pulse Synthesizers two channel Eurorack DJ module that reads direct from USB flash drive.

Each channel has:
Pitch control +/- 10%
High, mid and low Eq
Level control
Beat detection LED and CV output
Beat detection sensitivity control
LED level meter
Headphone cue
CV input for pitch and play / stop
Rotary encoder for song selection and track skipping

Overall:
Crossfader
Main stereo output
Headphone output
LCD showing waveform, track name, remain time, play time, total time and BPM

pulse.synthesizers@rocketmail.com"

Published on Apr 16, 2018 John Crombie

Published on Feb 16, 2018 John Crombie

"It’s coming out in Euro pretty soon I hope. I was going to add a clock input.
Clock output potentially, you mean linked to loop speed or BPM?"

John Crombie also worked on a prototype synthesizer named Pulse Synthesizers 4 to 5 years ago. The following is a playlist in reverse order featuring videos on the prototyping.

Playlist:
1. Pulse Synthesizers Case

Prototype case made from 3mm acrylic dark grey acrylic.

2. Pulse Synthesizers acid riff

Some acid sounding lines using the Pulse prototype. You can see me changing the filter envelope amount and resonance which has the most effect. Filters are all digital.

3. Pulse Synthesizers arpeggiator

Demo of the arp function in development. Height of vertical bars indicates pitch. Currently its connected via the USART to the synth DSP board.

4. Pulse Synthesizers, patch list selection

Patch list screen using rotary encoder with push button for selection.

5. Pulse Synthesizers oscillator wave selection

Oscillator wave selection shows a single period plot of the wave. Waves are selected using a rotary encoder.

6. Pulse Synthesizers filter development

Pulse Synthesizers prototype development.
I've added a second filter which can be in parallel, series or split between the two oscillators. Envelope amount and key follow are also added.

7. Pulse Synthesizers Prototype

Wavetable synthesizer prototype built on an STM32F4 microcontroller. MIDI notes are being triggered from Cubase software.
Functionality
2 x Wavetable oscillators with wavetable scanning knobs
Mixer for oscillators, noise and ring modulation
Envelope generator - ADSR controls
2 x Low Frequency Oscillators with frequency, depth and rotary encoders for selecting wave type and modulation destination
Delay effect with time and feedback controls
Reverb effect
11 x Filter types including LPF, HPF, BPF, Notch
MIDI 5 pin DIN interface
Graphic LCD 320 x 240 - only basic information currently shown however this will be expanded to cover a number of different menus.

Future work:
Sound patches
Non volatile memory for user patch storage
More filters
More wavetables
Acrylic case
PCB
External 16bit DAC interface (currently using inbuilt STM32F4 DAC)