Spin Semiconductor

I was wondering if anyone has done an FV-1 Pitch-controlled Filter? Let's just start with a simple LPF - based on the lowest fundamental pitch of a guitar signal. The filter corner frequency reduces as the pitch increases. I'm guessing single notes are mandatory here. The closest thing I've seen is ...

First off, let me just say, I'm new to the FV-1 and trying to read up on it as fast as possible but haven't read EVERYTHING, so I apologise if my questions have already been answered. Please go easy on me and just point me in the right direction. I'm keen to learn. On page 19 of the SPINAsm User Man...