[sdiy] MIDI too fast?

[grant at musictechnologiesgroup.com]

I noticed while playing with some step sequencer MIDI code, that on an
old 80's synth (JX3P) that you can't send a note-off then immediately
send the same note-on. The synth just "burp's" the note on.  If I leave
more than 8ms between them it works fine. 

I know from previous skulduggery that the JX3P has a main loop cycle
time of about 10ms, but this suggests a bug of sorts in the JX3P's MIDI
implementation or UART code -- clearly the received data is translated
out of order. The problem is, I don't have a lot of old synth's to
experiment with and even discovering this was a fluke. I hate adding
delays because this messes with the "tightness" of the sequence.

Anyway, a monophonic step sequencer by nature requires (obviously) that
the old note be turned off before the new note comes one. Is there any
collective wisdom as to what kind of gap might be suitable?  I know
other people have built various hard and soft sequencers.  If I turn the
note off half way through the clock cycle then there is no problem, but
the sound is pretty different.

GB