diy/electrical question: merge midi output from 2 devices?

As far as I know, no, it won't work. The two signals are clocked with start and stop bits, essentially like from a serial port (unless I'm REALLY spacing out more than usually) Go see for more details. You'll need some form of active device to merge the MIDI signals together and route them out. Sorry... Scott

midi is a serial protocol (like modems serial port stuff). it'd be like trying to splice two CAT5 network cables together - electrically it'll be weird and the two data streams will get all mashed up and corrupt. hmm... you could potentially split a single midi out into two midi outs but even then you might run into impedance problems. not worth risking damage to your gear if you do it wrong.

much thanks, dub and scott. i'm building a midi based turntable controller that allows me to trigger patches/samples from a homemade midi controller whilst scratching them from the turntable surface...i'll be able to create multisampled turntable soundfonts from vstis, reason, and chopped phrases and trigger them at leisure while manipulating their playback speed and rate. this removes the most limiting bit about turntablism - the linearity of a record as a sample playback medium. i'll be having to use 2 midisense units as control in conjunction with each other and i'll have to find a merger unit to get those 2 streams in line with each other. peace nym

or if you prefer DIY:

Maybe not an ideal solution for you, but amazingly it's cheaper to buy a MIDI interface than a MIDI merge box!