Tuesday, September 07, 2004

The Requirements

The basic idea is to: a) put the electronics into a rack mountable 19" case with the controls accessible from the front and the connectors at the back b) Build a MIDI interface that can at least make all the keys/notes respond to MIDI on/off messages on a selectable MIDI channel.

This presents a number of unique problems to overcome.

Firstly, the physical size of the circuit boards and their wiring requires a fairly large case. Most readily available 19" cases aren't big enough.

Secondly the front panel should look nice. This is a something that will take up space in my house and a well engineered product should look the part. It's problematic because I intend to use the original tablet switches and getting clean square cuts will not be easy.

Thirdly it's important to note that this is an fully polyphonic keyboard. There is a separate tone generated for each key and if you liked you could play every key at once. CV/Trigger interfaces are only used on monophonic keyboards that can only play one tone at a time. This MIDI interface will need to switch every tone individually rather than having one switch and a control voltage (CV) to set the note. I say this is a fairly unique problem as CV / gate interfaces are readily available and in both ready made form and from designs. More on this later.

I raise these three issues because they are the most particular to this project. If this was a small monophonic synth that only used rotary switches there would be nothing to write about You can already read about such projects here - http://www.synth.clara.net/resources.html and elsewhere.

The project is in two halves really. The mechanical and the electronic. I really need to address the mechanical problems first as they will make it easier to carry out the electronics development. Having all the boards in a cardboard box does not make it easy to work on them