I though it would be better to start a new thread on this, rather than tacking on to my previous posts.
Splicing together the EPE guitar to MIDI circuit with the Obsolete Technology MIDI to CV/gate is successful beyond what I ever hoped for. No code modification necessary to make the CV output sustain a note indefinitely - each new note just outputs it's respective 1v/oct voltage. Perfect for a mono synth and I can get percussive short attack/decay sounds, or very long climatic long attacks and held notes with slow and deep filter sweeps, plus anything in between. It's what I've been trying to do for the past 20 years using analogue circuits, without any success.
There's one major problem, though. Despite calibrating my oscillators again and setting up the MIDI to CV/gate for 1v/oct, there's a serious pitch error on the top E string played open - it's very sharp, as well as a slight sharpness on the subsequent F and F#. It's identical with the same notes played on the B string. All other notes are to pitch and the octave intervals from the bottom E string to the top E 12th fret are perfectly in tune. The open E voltage is 0.057v higher than it should be. Given that the voltage interval should be 0.083 between semitones, that's a pitch error of 68 Cents.
The schematics are here;
https://www.diystompboxes.com/smfforum/index.php?topic=128573.0The .ASM files are located at
http://sites.google.com/site/potulfx/marketing-docs/G2Mplus.asm?attredirects=0&d=1 for the guitar to MIDI. The MIDI to CV file is in the Obsolete technology link. I'm using version Midi_CV Obsoletetechnology_v1_2_16F628A.
I don't have any device that can play MIDI directly, otherwise I would be able to diagnose if the first section is causing the problem. I'm assuming though that the guitar to MIDI is well-proven and pitches correctly, as it's been a magazine article built by successfully by a number of people. Are the individual notes determined by a lookup table, or are they calculated mathematically? I'm not grasping how just certain notes can be out of tune and I've tried three different guitars (all in tune) with identical results. I also checked the D-A reference voltage and it's spot on 4.7v.