So I added a Mininova to my studio setup.
If I play the Mininova itself, it sounds fine (whether Cubase is static or during playback). If I play it using an Impulse controller keyboard through Cubase (again, both static and during playback), it sounds fine. If I fire up the step editor and create a part for it, it sounds fine while I’m triggering notes from the step editor. When I then play back the MIDI part that I’ve created manually in the step editor (or recorded using either the Mininova or the Impulse), the notes sound garbled, like the Mininova is receiving some weird extra data alongside the simple MIDI notes I created.
This happens if the MIDI part in Cubase is set to send the signal to the Mininova via USB-MIDI, or via a regular MIDI port. It doesn’t happen with any of my other Midi instruments, or any of the VST instruments.
I’m utterly baffled - anybody got any ideas?
Have you tried setting the midi filter in the preferences to disable Sysex to start with ?
I couldn’t find the MIDI Filter page, so I had a look in the operation manual (interestingly, I still can’t find the MIDI Filter page!) - the MIDI Filter only blocks certain information from being recorded or transmitted as MIDI thru. I have no problems when I’m using MIDI thru, and the problem occurs when I’ve created a MIDI part using the step editor - which means that I’ve not recorded any MIDI data at all, just entered a handful of note-on note-off messages.
I’m still baffled… 
Mind you, with the random way in which Cubase is being flaky lately, it could just be because it doesn’t like the colour of my t-shirt, or I haven’t used the right swear words at it while booting up…
I’ve solved the problem - at least, I think I have…
I was having another look around, and in the Project Synchronisation window, I had both MIDI Clock and MIDI Timecode being sent to the Mininova. It wants to see the MIDI Timecode in order to synchronise its tempo-based things like the arpeggiator/FX/etc, but it looks like it was the MIDI Clock that was upsetting it.
Now, if I can just get Cubase to agree with me that running a pair of MOTU Ultralite MK3s is a really really good idea, we’ll be laughing.