This is MIDIbox FM V2.1, the STM32F4 version of the Gen 2 MBFM. Please note that this is not an official successor to MIDIbox FM V1.4, nor is it a project that is intended to be easily replicated by members of the community, at least not in the forseeable future. For the thread on MIDIbox FM V2.0, the same synth before I upgraded the processor from the LPC17, see here (some build information, more pictures, etc.):   I have successfully upgraded my MIDIbox FM from the LPC17 core to