After I have finished the TTSH ARP 2600 and 1601 clone clone builds from Synthcube, there was one part missing to be finalized. My long term DIY project of a 61-keys DIY ARP 2600 TTSH Keyboard with a small eurorack section and CV outputs in a wooden housing which matches my TTSH and 1601.
I was looking for a 37-keys Fatar Keyboard for my mini-mini-moog project(s) when I stumbled over a cheap 61-keys Fatar Midi Controller Keyboard. Without thinking further and being confident I will find a use for it in a project, I bought the Keyboard a year ago. My first idea was to use it as a base to build a synthesizer with MIDI controller knobs for the Mutable Instruments Ambika. (I've the dartmobo open source midi controller on Arduino basis laying around) But after purchasing the TTSH, ARP 2600 clone, it was clear for what I will need the keyboard. That was when the DIY ARP 2600 TTSH keyboard idea was born.
DIY Keyboard for the TTSH, ARP 2600 clone
The only problems I had to solve were that it was a MIDI keyboard which has to control a synth via CV and the missing modulation functions when compared to the original ARP keyboards. In order to be able to control the TTSH via CV, I had to get a MIDI to CV interface. Luckily, I was able to buy such an interface together with the TTSH which is supposed to be build into the TTSH synth itself: Midimplant
The MIDImplant is really small. As per their homepage it was the world's smallest MIDI to CV converter (MIDI2CV) with dual channel, with Hz/V and V/oct response (user selectable). However, the producer of the MIDImplant made in the mean time an even smaller MIDI to CV interface, the MINICV. I think there are not much MIDI to CV interfaces out there who can beat functionality and size for the price. For my use, to build a keyboard for the TTSH, ARP 2600 clone, it was just perfect.
The modulation section of the Keyboard
I didn't want to build just a minimalistic keyboard controller. I wanted to have at least a bit of the modulation possibilities of the original keyboard. I decided to build in a small Eurorack section, where I could even change modules if I think that another module might be more suitable as the initial selected once.
Not having a modulation and pitch-bend wheel, I had to come up with an alternative idea. First I was checking modulation wheels for eurorack like the one Doepfer is offering. It wasn't my favourite option as they would take a lot of space. I continued searching and found the Synthrotek ribbon controller. Since they also offered a LFO and Multiple in small form factors, I decided to buy the diy kits.
Power for the Keyboard
To power the eurorack modules and the DIY ARP 2600 TTSH Keyboard, I got small eurorack power supply from Asuk-Snyth via eBay. This power supply is also powering the MIDImplant and the keyboard via a step-down converter.
The assembly of the keyboard for the TTSH, Arp 2600 clone
Although I had all parts together, it took me several months to finally assemble the keyboard due to other ongoing projects. I designed and 3D printed the eurorack section as well as a side, back and bottom cover. The space for the eurorack section was tight but I managed to get everything in place after removing the wood underneath the eurorack modules. All in all the result looks and plays nice. Together with the ARP 1601 clone it is a really fantastic setup.