Here is a PC layout for a board that I'm using with my EK-3 encoder. It allows you to neatly add all those fursh-lugginer diodes and substantially reduces the amount of point-to-point wiring needed. All of the diodes solder to the board so the only wiring necessary is from my PC board to the key switches and bus bars. Transposing the keyboard up from 000000 is simply a matter of attaching the wires from the bus bars to the appropriate pads on my PC board.

You'll notice that the board can handle up to 49 keys (4-octave) but of course works just as well with 3 octaves (which is what I'm using it with now, till I find a good 4-octave kybd). In fact, by extending the pattern, you can use it for 5 octaves. Also note that all keyboard connections are brought out to a dual readout connector. By sawing a 16-pin DIP socket in half and soldering the two halves into the connector holes on the component side of my board, and then soldering bits of excess resistor lead into the connector holes on the EK-3, the two boards just plug together, no point wiring involved!

PAIA has available a full 64-note version of Bob's matrix board. Order #KBM-1 for $6.95.