We now need to make the Teensy waveforms respond to modulation.Ĭonnect the LPF output to your MOD wheel (pot) and run the pot's wiper back into an A/D input on the teensy, using the circuit shown in the ADC audio input section in the Audio System Design Tool, or something similar to provide an AC coupled input centered around a DC voltage. We now have an analog LFO output voltage that can be applied to the mod input of any analog modular VCO. Take the analog voltage output from the DAC, run it through a low pass filter (series resistor, cap to ground) to remove noise and aliasing products. Apply the output to the internal DAC in the Teensy. This is not needed for basic modulation.īuild your LFO using a waveform, wave table, or even a sequencer that steps through a list of variables.
I wanted my synth to be compatible with the 1V/oct standard used in most modular stuff so I spent nearly forever figuring out how to make the waveforms respond to 1V/oct. I have FM modulation of all of the waveforms working in my synth.
