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Can two MIDI devices be on the same output? Answered

I'm making a keytar and was planning on finding a keyboard with  the number of keys that I want and a MIDI output, but I'm thinking that if I do find a keyboard, it won't have the pitch-bend functionality. Could I have an Arduino read a membrane potentiometer and send that out the same MIDI port that the keyboard is sending the note data out of and have the pitch bend affect the note?


If the keytar is simply going to be a MIDI controller (and not produce sounds on its own) then what you want to do is very possible. You'll need to read up on MIDI merging. The MIDI out from the keyboard would go into the Arduino and then be merged with the pitch bend info from the sensor strip and then sent out to the sound module/computer/whatever.

Merging MIDI is a little tricky because it is a serial protocol and you can't interrupt MIDI messages in the middle of an event (ignoring SYSEX messages). The Arduino would need to buffer the incoming MIDI data from the keyboard and intersperse the pitch bend messages on the output.

I really can't say for sure, but from my understanding of MIDI, it is possible, but unless you can find something pre-made, it would be one heck of a huge project. I really like lemonie's idea about effect processing on the audio line. (I realize that keytars are usually MIDI, but that might be your best bet.)

I'm not sure what the result would be but you can combine the signals with a mixer. A mixer allows you to combine a number of signals and control them without them affecting the other signals or damaging any equipment. Mixers can be build very easily or bought on Ebay. I bought an 8 port mixer for less than $10 shipped.

No, that will not work. Mixers are designed for audio. Even though MIDI will be translated into audio, it is really a data transfer protocol. Some mixers will have some of the following: MIDI in, MIDI out, and sometimes MIDI through. But never more than one of each, and they are rarely used.

You are plannung to make a MIDI device from scratch, or you just want to add pitch-bend function to the MIDI keyboard?


Add a pitch-bend function to the MIDI keyboard.

The keyboard output to audio isn't MIDI, so you could use an audio-effect device on that.
If you want the pitch-bend in the MIDI data, you'd need different software running on the keyboard to format it into the MIDI file.