The XFM2 is a huge synthesizer in a tiny space that has 4 times the capacity of the previous version. They’ve upgraded the audio quality, simplified the build and given us all a DX7 kit for $99.
The synthesizer is built on the Xilinx Artix-7 35T FPGA chip mounted on the pre-assembled Digilent CMOD A7-35T board. This is combined with a new 24-bit Adafruit UDA1334A DAC which provides the audio output. Put these on a board with a handful of other components and a MIDI port and you have a kick-ass FM synthesizer for under $99 in parts.
The build is pretty simple and with a bit of prototype board and the schematic you can see what needs to be soldered to where. The manual doesn’t come with step-by-step instructions so you might have to be a bit bold and use your brain.
The result is a flippin’ 64-voice, 2-part, 6-operator FM synthesizer with a shed load of effects.
So, what are the details? Each voice has 6 operators and each operator has 2 oscillators and can choose from 8 waveforms. There’s a 7-segment loopable envelope for each operator and one for the pitch. For modulation each voice has an LFO and individual operators can set sensitivity. There’s portamento in both poly and mono modes. There’s extensive MIDI implementation and four assignable performance controls for each program that you can map to a handy knob.
There are two effects engines, one for each part offering Decimator, Bitcrusher, Filter, Chorus/Flanger, Phaser, Amplitude Modulator and Delay all of which can be used together. There’s also a stereo reverb and an arpeggiator.
You can store up to 128 programs on the chip and it’s fully programmable from a computer via USB.
Watching the video it sounds completely brilliant. With a properly mapped MIDI controller you could really get into the sounds. Or perhaps it needs a VST editor and librarian – that would be awesome.
The full BOM, Binaries and operation instructions are on the website, you just need to order the bits.
- XFM2 website.