Strange MIDI routing issue (solved: „middle C As“ - problem)



I use 2 laptops on stage - one as hot standby. Songs, racks and setlists are synchronized via dropbox.

This worked flawlessly since months. Today I had a strange effect: after adding a song to my setlist I created some time ago this behaved differntly on both laptops.

After proofing it was really the exact same song on both laptops I found that every MIDI routing in this song seemed to be transposed by 1 octave on the second laptop compared to the same song on the first laptop (f.e. a routing with a keyrange from f3 to g4 is showing up as f4 to g5 on the other laptop).

Surprisingly this had no effect on nearly all routings means: even though everything is transposed (nearly) every routing produces exactly the same audio as on the other laptop when triggered from the same keyboard.

The reason why I’m observing an issue at all in this song is there was a suppress events filter in one routing allowing only three notes to pass. Here the note values are not transposed which easily explains the different behavior.

After changing this filter by one octave everything was fine again (but this would result in a differnt song for the second laptop).

I meanwhile could work around this for the moment by substituting the routing by some others not needing the filter anymore (for gods sake cantabile is extremly flexible as we all know :wink:).

Next was to have a look at the other songs and guess what: the one octave shift is happening in all of them.

Even though I can live with the situation as is this is totally annoying and I have no clue what‘s going on here.

So any enlightment is warmly welcome,

Cheers, humphrey :star_struck:


Not sure but this was an interesting discovery for me. There are 2 numbering systems. Commonly, “everyone” calls Middle C C3 (C in the 3rd octave from the left, code 60 in decimal, 3C in hexidecimal). Yamaha came up with a system that calls Middle C C4 (C in the 4th octave from the left, code 72 in decimal, 48). Yamaha’s Middle C is thus one octave apart from the common designation. I hope I shifted the right way with this. Could that have something to do with your issue?


Yes, that was the reason behind: whereas the key areas in routings simply follow the changed numbering introduced by a change in the „middle C As“ setting (in fact you don‘t notice it while playing) key settings in a suppress event filter are untouched!

In my case one laptop was set to middle C = 4 the other one to middle C = 5 (I didn‘t notice this - in fact I wasn‘t aware of the middle C As setting - no clue when this may have hapoened…).

This worked flawlessly for 40 songs. Adding another song which had a suppres events filter suppressing notes in it (a mechanism I normally don‘t use) the mismatch became obvious.

Luckily some deeper search in forum posts pointed me to a thread Neil Durant postet some time ago which hinted me to the core of the problem. So I set the problem to solved.

Regards, humphrey