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3 Voice Paraphonic Synthesizer for Arduino Uno
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DigitalSynthVRA8P
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LICENSE
README.md
generate-sample-midi-stream.rb
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vra8-p-ctrl.html

README.md

Digital Synth VRA8-P 1.0.1

Concept

  • 3 Voice Pseudo Polyphonic Synthesizer for Arduino Uno

Features

  • 3 Voice Pseudo Polyphonic Synthesizer (Paraphonic Synthesizer), MIDI Sound Module
  • Serial MIDI In (38400 bps), PWM Audio Out (Pin 6), PWM Rate: 62500 Hz
    • We recommend adding a RC filter circuit to reduce PWM ripples
    • A cutoff frequency 10.6 kHz (R: 150 ohm, C: 100 nF) works well
    • CAUTION: Click sounds may occur when you connect the audio out to an amp/a speaker or reset the board
  • Sampling Rate: 15625 Hz, Bit Depth: 8 bits
  • LPF Attenuation Slope: -12 dB/oct
  • Recommending Hairless MIDI<->Serial Bridge to connect PC
  • Files
    • DigitalSynthVRA8P.ino is a sketch for Arduino/Genuino Uno
    • make-sample-wav-file.cc is for Debugging on PC
      • Requiring GCC (G++) or other
      • make-sample-wav-file-cc.bat makes a sample WAV file (working on Windows)
    • generate-*.rb generate source files
      • Requiring a Ruby execution environment

VRA8-P CTRL

  • Parameter Editor (MIDI Controller) for VRA8-P, Web App
  • We recommend Google Chrome, which implements Web MIDI API
  • VRA8-P CTRL includes PRESET programs
  • Recommending loopMIDI (virtual loopback MIDI cable) to connect VRA8-P
  • CAUTION: Click sounds may occur when you change the controllers (especially AMP EG and FILTER CUTOFF)
  • CAUTION: Low FILTER CUTOFF with high FILTER RESO can damage the speakers

Controllers

+---------------+----------------+----------+----------------+-----------------+
| Controller    | Value 0        | Value 64 | Value 127      | Notes           |
+---------------+----------------+----------+----------------+-----------------+
| UNISON        | OFF            | (ON)     | ON             | 3 Voice UNISON  |
| OSC WAVEFORM  | SAW (SAWtooth) | ORGAN    | SQ (SQuare)    |                 |
| OSC DETUNE    | 0.24 Hz        | 2.1 Hz   | 3.8 Hz         |                 |
| AMP EG        | OFF            | (ON)     | ON             |                 |
+---------------+----------------+----------+----------------+-----------------+
| FILTER CUTOFF | 0.22 kHz       | 1.2 kHz  | 7.0 kHz        | Range 4 to 124  |
| FILTER RESO   | Q = 0.71       | Q = 1.4  | Q = 2.6        | RESOnance       |
| FILTER EG AMT | -125 (EG 100%) | 0        | +124 (EG 100%) | Modulate CUTOFF |
| EG DECAY      | 21 ms          | 1.4 s    | 5.4 s          | DECAY Time      |
+---------------+----------------+----------+----------------+-----------------+

MIDI Implementation Chart

  [Experimental Synthesizer]                                      Date: 2016-09-22       
  Model  Digital Synth VRA8-P     MIDI Implementation Chart       Version: 1.0.1         
+-------------------------------+---------------+---------------+-----------------------+
| Function...                   | Transmitted   | Recognized    | Remarks               |
+-------------------------------+---------------+---------------+-----------------------+
| Basic        Default          | x             | 1             |                       |
| Channel      Changed          | x             | x             |                       |
+-------------------------------+---------------+---------------+-----------------------+
| Mode         Default          | x             | Mode 3        |                       |
|              Messages         | x             | x             |                       |
|              Altered          | ************* |               |                       |
+-------------------------------+---------------+---------------+-----------------------+
| Note                          | x             | 0-127         |                       |
| Number       : True Voice     | ************* | 24-84         |                       |
+-------------------------------+---------------+---------------+-----------------------+
| Velocity     Note ON          | x             | x             |                       |
|              Note OFF         | x             | x             |                       |
+-------------------------------+---------------+---------------+-----------------------+
| After        Key's            | x             | x             |                       |
| Touch        Ch's             | x             | x             |                       |
+-------------------------------+---------------+---------------+-----------------------+
| Pitch Bend                    | x             | x             |                       |
+-------------------------------+---------------+---------------+-----------------------+
| Control                    16 | x             | o             | UNISON                |
| Change                     17 | x             | o             | OSC WAVEFORM          |
|                            18 | x             | o             | OSC DETUNE            |
|                            19 | x             | o             | AMP EG                |
|                            20 | x             | o             | FILTER CUTOFF         |
|                            21 | x             | o             | FILTER RESO           |
|                            22 | x             | o             | FILTER EG AMT         |
|                            23 | x             | o             | EG DECAY              |
+-------------------------------+---------------+---------------+-----------------------+
| Program                       | x             | x             |                       |
| Change       : True #         | ************* |               |                       |
+-------------------------------+---------------+---------------+-----------------------+
| System Exclusive              | x             | x             |                       |
+-------------------------------+---------------+---------------+-----------------------+
| System       : Song Pos       | x             | x             |                       |
| Common       : Song Sel       | x             | x             |                       |
|              : Tune           | x             | x             |                       |
+-------------------------------+---------------+---------------+-----------------------+
| System       : Clock          | x             | x             |                       |
| Real Time    : Commands       | x             | x             |                       |
+-------------------------------+---------------+---------------+-----------------------+
| Aux          : Local ON/OFF   | x             | x             |                       |
| Messages     : All Notes OFF  | x             | o             |                       |
|              : Active Sense   | x             | x             |                       |
|              : Reset          | x             | x             |                       |
+-------------------------------+---------------+---------------+-----------------------+
| Notes                         |                                                       |
|                               |                                                       |
+-------------------------------+-------------------------------------------------------+
  Mode 1: Omni On,  Poly          Mode 2: Omni On,  Mono          o: Yes                 
  Mode 3: Omni Off, Poly          Mode 4: Omni Off, Mono          x: No                  
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