Fatar TP9S 44 note keybed pinout

Today the Fatar TP9S 44 note keybed I ordered arrived so I set about going through it with a continuity test to get the pinout for the diode matrix. This wasn't anything I'd seen anywhere online for the 44 note keybed; Doepfer has the 37 key and 49 key matrixes up on their website but not the 44. Turns out the connector on the 44 is the same as on the 37 key, a 20 way Micro-Match connector. If you're looking for the mate for it to run to your electronics the male part is here (Element 14 link).

Here is the pinout for the 37 key model from the Doepfer website:

The 44 key has the same pinout on the connector with the addition of another lot of MK/BR contacts on the last two unused pins. The order goes round clockwise so the far right pin is MK5 and then other BR5.

The keyboard pins will be wired up to digital pins on the Arduino so they can be scanned to detect keypresses. At this stage velocity sensitivity is not required so the timing data between break and make is not required, which makes the programming a lot easier.

DIY 4-Voice Europoly overview

I'm setting this blog up to document the work I'm attempting on a DIY 4-voice Eurorack keyboard synth. It's early days yet and all I have is a plan, a 3D model in Sketchup and the beginnings of the Arduino code.

The keybed will be a 44 key Fatar TP9S which I've ordered on ebay. The brain that will scan the keybed and output CV and gate will be an Arduino Due. I chose the Due as it has a lot of ins and outs and so will be expandable later if I want to add features to the electronics. The Due will be outputting gates on its digital pins and CV via an Analog Devices AD5628 Digital to Analog Converter. Running the AD5628 at 5V will give me 5 octaves of CV output, which means the 3 1/2 octave keyboard will be able to be transposed one octave.

Four DAC channels will be used for CV initially while the other four will be left unused. In time I intend to use the other four for a software envelope output per voice, but that will not be part of the initial spec.

The two DACs on the Due will also be used for modulation outputs in time (most likely a quantised sequencer output) but at this stage will remain unused. These outputs run at a max of 3.3V which limits their usefulness.

Voice modes under consideration are Poly 4, Poly 3 (to leave a voice free to be sequenced), Unison 2 voice (A&C, B&D), Unison. A Poly 3 + Sequence mode could be written which would enable the keyboard to be used to input notes to the sequence when a button was held down, when the button was released the sequence would play and the keyboard would play the remaining three voices. Alternatively eight potentiometers could be used, hooked up to eight analog input pins for a simple sequencer like the Oberheim Two Voice.

Physically the synth will be constructed of 12mm marine ply covered in tolex and will have two rows of 150HP vector rails for mounting of Eurorack modules. At this stage 4x Pittsburgh Modular Synthesizer Blocks are envisaged for the core voices, with additional modules to be added later for additional functionality. A key aim for this synth is to have stereo outputs with stereo spring reverb. Voltage controlled panning of individual voices is also an aim, particularly for use with a quadrature LFO for 90 degree out of phase swirling voices.