- 2022-06-26 ISGK Instruments
- https://github.com/risgk/digital-synth-vra8-q
- Quadraphonic (4-voice Paraphonic) Synthesizer (MIDI Sound Module) with Stereo Chorus Effector for Arduino Uno
- We strongly recommend Arduino AVR Boards core 1.8.3
- If you use other than AVR Boards core 1.8.3 (or modified this sketch), the sketch may not work well
- CPU Busy LED (LED L) may almost always lit, rather than flashing occasionally
- If you use other than AVR Boards core 1.8.3 (or modified this sketch), the sketch may not work well
- v5.2.0: Improve Monophonic and Legato Modes (Oscillator 2 Pitch)
- v5.1.0: Fix Portamento in Monophonic Mode; Add MONO OSC2 PITCH Control; Memory last 4 notes in Monophonic and Legato Modes; Improve sound of Monophonic and Legato Modes; Make envelopes smoother (Improve EG); Change the layout of VRA8-Q CTRL; Other changes
- v5.0.1: Fix a bug that OSC LEVEL is not updated in program change
- v5.0.0: Fix wave tables (Reduce noise); Change the range of CUTOFF frequency (min: 452.9 Hz, max: 14.5 kHz); Improve LFO RATE (min: 0.2 Hz, max: 20 Hz); Add EG > PITCH, LFO WAVE, LFO FADE TIME, MONO OSC2 MIX, and MONO OSC2 DETUNE; Add Legato Mode (Monophonic, Single Trigger, Auto Portamento); Change the recommended circuits; Rename PRESET #7 NEUTRAL to INITIAL; Other changes
- v4.0.0: Add PORTAMENTO Time; Remove AC coupling capacitors from the recommended circuit
- v3.2.0: Add Pseudo-Stereo Chorus Mode; Assign free voices in Oscillator index order; Change CPU Busy LED lighting condition; Other changes
- v3.1.0: Fix the problem pitch bend is minimized by Reset All Controllers; Add VOICE Mode (PARA/MONO); Expand the range of CUTOFF frequency (min: 440 Hz, max: 14.08 kHz); Improve VELOCITY > CUTOFF; Fix the instability of the pitch when a note (Gate) is turned on; Change PRESET; Other changes
- v3.0.0: Improve sound quality; Fix Oscillator pitch; Increase the CUTOFF frequency slightly (min: 880 Hz, max: 14.08 kHz); Change the Q range of RESONANCE (min: 0.7, max: 8.0); Increasing RESONANCE decreases the filter gain; Support Velocity > CUTOFF (OFF/ON); Reduce pop noise when turning notes ON and OFF; Enable Short Delay FX; Change PRESET programs; Support All Sound OFF and Reset All Controllers; Other changes
- v2.2.0: Change PRESET; Other changes
- v2.1.0: Improve sound quality; Change PRESET; Other changes
- v2.0.0: Add Mono and Stereo 2-phase Chorus modes; Improve the pitch; Introduce No Decay (DECAY = 127); Improve the recommended circuit; Other changes
- v1.1.2: Change the oscillator drift
- v1.1.1: Modify the PRESET programs
- v1.1.0: Change the behavior of the oscillators
- v1.0.3: Fix the problems with bass or treble note on
- v1.0.2: Fix the oscillator frequency
- v1.0.1: Fix the release date
- Serial MIDI In (38.4 kbps)
- We recommend Hairless MIDI<->Serial Bridge to connect PC
- NOTE: A combination of a MIDI Shield (or MIDI Breakout) and a power supply adapter is better to avoiding USB noise
- To use MIDI Shield (or MIDI Breakout), take
#define SERIAL_SPEED (31250)(31.25 kbps) in"DigitalSynthVRA8Q.ino" - Even using only the power supply adapter significantly reduces USB noise
- To use MIDI Shield (or MIDI Breakout), take
- PWM Audio Out (Unipolar, Line Level) L/Mono: Pin D5 (or D6), R: Pin D11
- Sampling Rate: 31.25 kHz, PWM Rate: 62.5 kHz, Bit Depth: 8 bit
- We recommend adding a RC filter (post LPF) circuit to reduce PWM ripples
- A 1st-order LPF with a cutoff frequency 7.2 kHz (R = 220 ohm, C = 100 nF) works well
- A 2nd-order LPF with a cutoff frequency 33.9 kHz (R1 = R2 = 47 ohm, C1 = C2 = 100 nF) works well, too
- Files
"DigitalSynthVRA8Q.ino"is a sketch for Arduino Uno Rev3 (ATmega328P)"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"generates source files- Requiring a Ruby execution environment
- MIDI Controller (Editor) Application for VRA8-Q, HTML App (Web App)
- VRA8-Q CTRL converts Program Changes (#0-7 for PRESET) into Control Changes
- VRA8-Q CTRL stores the current control values and the user programs (#8-15) in a Web browser (localStorage)
- We recommend using Google Chrome, which implements Web MIDI API
- We recommend loopMIDI (virtual loopback MIDI cable) to connect VRA8-Q
- OSC WAVE (SAW/PLS) = Oscillator Waveform
- 0 (0-63): Saw Wave
- 127 (64-127): Pulse Wave (Square Wave)
- CUTOFF = Filter Cutoff Frequency
- RESONANCE = Filter Resonance
- AMP EG (OFF/ON)
- 0 (0-63): Off (Gate)
- 127 (64-127): On (EG)
- ATTACK = EG Attack Time
- DECAY = EG Decay Time
- 127: No Decay
- SUSTAIN: EG Sustain Level
- LFO WAVE (T/T2/S/RND/P) = LFO Waveform
- 0 (0-15): Triangle Wave
- 32 (16-47): Triangle Wave 2 (Key Sync)
- 64 (48-79): Saw Wave (Key Sync)
- 96 (80-111): Random Wave (Key Sync)
- 127 (112-127): Pulse Wave (Square Wave, Key Sync)
- CHORUS DEPTH
- 0: Delay Time +/- 0.0 ms (min)
- 32: Delay Time +/- 2.0 ms
- 64: Delay Time +/- 4.1 ms
- 126: Delay Time +/- 8.1 ms (max)
- CHORUS RATE
- 4: LFO Frequency 0.06 Hz (min)
- 32: LFO Frequency 0.48 Hz
- 64: LFO Frequency 0.95 Hz
- 127: LFO Frequency 1.9 Hz (max)
- CHORUS DELAY TIME
- 0: 0.03 ms (min)
- 64: 8.2 ms
- 80: 10.3 ms
- 127: 16.3 ms (max)
- CHORUS (-/M/PS/S/S2) = Chorus Mode
- 0 (0-15): Chorus Off
- 32 (16-47): Mono Chorus
- 64 (48-79): Pseudo-Stereo Chorus
- 96 (80-111): Stereo Chorus
- 127 (112-127): Stereo 2-phase Chorus
- VOICE (PARA/MONO/LGT) = Voice Mode
- 0 (0-31): Paraphonic
- 64 (32-95): Monophonic (Multi Trigger)
- 127 (96-127): Legato (Monophonic, Single Trigger, Auto Portamento)
- PORTAMENTO = Portament Time
- MONO OSC2 MIX (-/HF/FL) = Oscillator 2 Mixing Level in Monophonic and Legato Modes
- 0 (0-31): Off, 0% (Oscillator 1: 200%)
- 64 (32-95): Half, 100% (Oscillator 1: 175%)
- 127 (96-127): Full, 150% (Oscillator 1: 150%)
- MONO OSC2 PITCH = Oscillator 2 Pitch in Monophonic and Legato Modes
- MONO OSC2 DETUNE = Oscillator 2 Detune amount in Monophonic and Legato Modes
- Setting Q1 -- CHORUS DEPTH: 32, CHORUS RATE: 32, CHORUS DELAY TIME: 80, CHORUS: 127
- Setting D1 -- CHORUS DEPTH: 32, CHORUS RATE: 16, CHORUS DELAY TIME: 80, CHORUS: 127
- Setting D2 -- CHORUS DEPTH: 40, CHORUS RATE: 16, CHORUS DELAY TIME: 60, CHORUS: 127
- Setting D3 -- CHORUS DEPTH: 24, CHORUS RATE: 32, CHORUS DELAY TIME: 60, CHORUS: 127
- Setting U1 -- CHORUS DEPTH: 32, CHORUS RATE: 32, CHORUS DELAY TIME: 20, CHORUS: 127
- Setting U2 -- CHORUS DEPTH: 32, CHORUS RATE: 48, CHORUS DELAY TIME: 20, CHORUS: 127
[Quadraphonic Synthesizer] Date: 2022-06-26
Model: Digital Synth VRA8-Q MIDI Implementation Chart Version: 5.2.0
+-------------------------------+---------------+---------------+-------------------------+
| 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 | ************* | 24-96 | |
+-------------------------------+---------------+---------------+-------------------------+
| Velocity Note ON | x | o (V=1-127) | For VELOCITY > CUTOFF |
| Note OFF | x | x | |
+-------------------------------+---------------+---------------+-------------------------+
| After Key's | x | x | |
| Touch Ch's | x | x | |
+-------------------------------+---------------+---------------+-------------------------+
| Pitch Bend | x | o | |
+-------------------------------+---------------+---------------+-------------------------+
| Control 1 | x | o | MODULATION |
| Change 11 | x | o | EXPRESSION |
| 64 | x | o | SUSTAIN PEDAL (OFF/ON) |
| | | | |
| 24 | x | o | OSC WAVE (SAW/PLS) |
| 108 | x | o | OSC LEVEL |
| 104 | x | o | EG > PITCH (-/+) |
| | | | |
| 16 | x | o | CUTOFF |
| 17 | x | o | RESONANCE |
| 18 | x | o | EG > CUTOFF (-/+) |
| 31 | x | o | AMP EG (OFF/ON) |
| | | | |
| 23 | x | o | ATTACK |
| 19 | x | o | DECAY |
| 27 | x | o | SUSTAIN |
| | | | |
| 81 | x | o | LFO DEPTH |
| 80 | x | o | LFO RATE |
| 82 | x | o | LFO > PITCH (-/+) |
| 83 | x | o | LFO > CUTOFF (-/+) |
| | | | |
| 14 | x | o | LFO WAVE (T/T2/S/RND/P) |
| 15 | x | o | LFO FADE TIME |
| | | | |
| 60 | x | o | CHORUS DEPTH |
| 61 | x | o | CHORUS RATE |
| 62 | x | o | CHORUS DELAY TIME |
| 63 | x | o | CHORUS (-/M/PS/S/S2) |
| | | | |
| 85 | x | o | PITCH BEND RANGE |
| 89 | x | o | VELOCITY > CUTOFF |
| 87 | x | o | VOICE (PARA/MONO/LGT) |
| 22 | x | o | PORTAMENTO |
| | | | |
| 25 | x | o | MONO OSC2 MIX (-/HF/FL) |
| 20 | x | o | MONO OSC2 PITCH |
| 21 | x | o | MONO OSC2 DETUNE |
| | | | |
| 90, 112-119 | x | x | (RESERVED) |
+-------------------------------+---------------+---------------+-------------------------+
| Program | x | o | |
| Change : True # | ************* | 0-7 | |
+-------------------------------+---------------+---------------+-------------------------+
| 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 : All Sound OFF | x | o 120 | |
| Messages : Reset All | x | o 121 | |
| Controllers | | | |
| : Local ON/OFF | x | x | |
| : All Notes OFF | x | o 123-127 | |
| : 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