Can you use the Voyager rack unit with electric guitar?

or must it be connected to a keyboard?

The guitar will not trigger the oscillators directly. A MIDI keyboard is a must for that.

glyph is right, but you can certainly plug the guitar into the mixer ext. in and mix with the voyager oscillators and or use the filters on the rme to filter the guitar sound.

You could get this:

http://blacet.com/IO.html

With this you could control the EG’s on the Voyager’s filters that you were running the guitar through. Also mess with LFO/S&H rates, VCO,Waveform FM over the Voyagers filters for some messed up sounds.

It will not control the pitch of the Voyager. You would need some Midi pickup controler or Pitch to CV controler(like in a Korg MS20/X-911)

See this thread:

http://www.moogmusic.com/forum/viewtopic.php?t=1101&highlight=axon