1. The Post-Moog Digitally Controlled Analog Synthesizer Group Members PM-DCAS • Logan Snow • Robert Estelle • Greg Hartl • Toan Ho

2. Project Summary • Technical Objectives • Create a modular audio synthesis system • Support MIDI input • Create an innovative user interface • Support storage and recall of presets • Maintain a low material cost • Motivation • Target hobbyist musicians and synth enthusiasts • Recreate classic analog sounds

3. Financial Breakdown

4. System Design User Interface Digital Control Board System Interface Board MIDI Keyboard Output Amplifier Analog Synthesis Hardware Debug Monitor

5. User Interface Attack Decay Sustain Release • Noise Level • Sine • Saw • Tri Duration • Rect Pulse Width Vibrato Center Resonance Volume Options Filter Mode Modulation Variance Filter LPF HPF Fixed Tri BPF Sine P1 P2 P3 P4 Save

6. Attack, Decay, Sustain, Release(ADSR Control)

7. RKA – Rotary Knob Assembly • Each digital rotary encoder is read by a dedicated microcontroller (PIC16F87) • LEDs indicate position of knob to user • Display can be reset by master microcontroller to indicate new position PICTURE HERE

8. DCB - Digital Control Board MIDI Input DACs PICTURE HERE Master Microcontroller (PIC24FJ64GA002) Debug Port SIB Connector Rotary Knob Connectors

9. Master Microcontroller • Microcontroller reads inputs: • MIDI from external music device • Rotary knob positions through I2C • Debug commands from serial port • Microcontroller sets outputs: • LED positions using I2C LED drivers • Analog control voltages using I2C DACs • All digital control occurs on two I2C busses

10. Digital Control Scheme … … LED Driver Slave Microcontroller LED Driver … MIDI Keyboard Master Microcontroller I2C DAC I2C DAC … Debug Monitor VCO Control Filter Resonance Other Control Voltages

11. SIB – System Interface Board I’m a big picture of the SIB + VCO VCA1..4 VCF Noise VCA5 VCA6 • Receives control signals from the DCB • Connects to the power supply • Routes all signals between the analog boards • Mixes the intermediate signals Output

12. Analog Signal Flow + VCO VCA1..4 VCF Noise VCA5 VCA6 Output

13. VCO – Voltage Controlled Oscillator I’m a big picture of the VCO + VCO VCO VCA1..4 VCF Noise VCA5 • 1V/Octave control input • At least 3 Octave range • Several Outputs: • Sine wave • Sawtooth wave • Rectangular wave with PWM • Triangular wave • Each output has corresponding VCA VCA6 Output

14. Noise Source + I’m a big picture of the noise source VCO VCA1..4 VCF Noise Noise VCA5 VCA6 • White noise • Adjusted through a VCA before mixing with other signals Output

15. VCA – Voltage Controlled Amplifier I’m a big picture of the VCA + VCO VCA1..4 VCF Noise VCA5 VCA6 • Logarithmic amplitude control voltage • Three boards with two amplifiers each • VCA1..4 modulate VCO outputs • VCA5 is dedicated to the noise source • VCA6 output connects to final synthesizer output Output

16. VCF – Voltage Controlled Filter + VCO VCA1..4 I’m a big picture of the VCF VCF VCF Noise VCA5 • Voltage-controlled resonance and center frequency • Multiple Filter Outputs • High Pass • Low Pass • Band Pass VCA6 Output

17. Analog Signal Flow + VCO VCA1..4 VCF Noise VCA5 VCA6 Output

18. Task Status

19. Issues Encountered • Shipping problems • Solder flux disaster • Old SIB revision sent for fabrication • Post-fabrication board modifications • Pin size mismatches on DCB

20. Planned Demonstration • MIDI input from a music keyboard • Auditory verification of audio parameter manipulation • Visual verification of user interface correlation with audio parameter adjustment • Saving and loading of presets

21. Questions? ?