The XFM2 Synthesizer Module
The XFM2 Synthesizer Module is the second generation of the XFM DIY Synthesizer Project. XFM2 is a 64-voice, 2-part, 6-operator FM Synthesizer with built-in effects processor, built on an FPGA chip.
FPGA power-up
Stepping up from the Xilinx Spartan-6 used in XFM, XFM2 is based on the Xilinx Artix-7 35T FPGA chip. With almost four times the capacity of the previous one, this new chip offers plenty of space for a more complex build.
24-bit DAC
Also stepping up from XFM, the simple 16-bit digital-to-analog converters have been upgraded to a 24-bit dedicated chip, with high-end output filters. The analog outputs have then greater dynamic range, higher S/N ratio and lower distortion.
Simplified build
The build is based on two pre-assembled development boards: the Digilent CMOD A7-35T (FPGA, USB, SRAM) and the Adafruit UDA1334A (DAC). This combination allows to get the module running in less than 10 components (about $99 total cost).
Feature Set
2-part, 64-voice polyphony (32-voice for each part)
Polyphonic/Monophonic Legato modes
The two parts can work as individual synthesizers, or layered
6 operators per voice
2 independent oscillators on each operator
8 waveforms per operator
Variable modulation algorithm (extended from XFM to allow for multiple feedback loops)
A 7-segment, loopable Envelope Generator for each operator
(DAD1D2SR1R2, with time and level controls for each segment)7-segment loopable Pitch Envelope Generator
Per-voice LFO with Triangle, Square, Sine, Random waveforms
Per-operator adjustable LFO sensitivity for pitch and volume
Per-operator adjustable velocity tracking, keyboard tracking
Polyphonic /Monophonic portamento
Pitch bend range adjustable independently for up and down directions
Extensive MIDI implementation (pitch bend, mod wheel, aftertouch, sustain pedal, breath ctl, foot ctl, volume, pan, chorus, reverb, delay, tremolo, etc.)
Four per-program assignable Performance Controls, which allow any parameter to be controlled by MIDI continuous controls messages.
All synthesizer and effects parameters (300+) adjustable via MIDI system exclusive messages.
Two complete stereo-in/stereo-out effect processors (one per part), including:
Decimator
Bitcrusher
Filter
Chorus/Flanger
Phaser
Amplitude Modulator
Delay
All of above effects can be run simultaneously, for both parts
Stereo Reverb with individual sends per part
Arpeggiator
128 programs memory (EEPROM)
MIDI in, optional thru
Samplerate-grade modulations
24-bit stereo analog out
Optional Stereo, 24-bit SPDIF digital out
Battery friendly, low power operation
Fully programmable (connecting it to a PC via USB)
256 microtuning scales
Nearly zero latency (< 0.5ms)
Extremely fast boot time (< 100ms)
