[sdiy] passive MIDI merge?

[Simon Gatrall]

>
>Come to think of it, this is never going to work. A MIDI output
>is never idle because MIDI devices are supposed to send an
>active sensing message every 300 ms and these messages are
>fatally going to collide with each other and with your
>controller messages and SYSEX. At best, transmission is going to
>be unreliable. At worst, it could upset the MIDI device on the
>receiving end. I'm afraid there's no sane way to merge MIDI
>inputs at the electrical level.
>
>--
>André Majorel <amajorel at teaser.fr>
>http://www.teaser.fr/~amajorel/

My experience is that very very few pieces of gear send "active 
sense".  I have the official MIDI spec from the MIDI Manufacturer's 
Association.  It is an optional part of the MIDI spec, and almost no 
one implements it.  On the few bits of gear that do implement it, you 
can often turn it off.

-s!mon