Octatrack : Midi Loopback Question(s)

Hi. I just wanna piggyback off this thread with a question relating to MIDI myself.

I want to loop MIDI from my Octatrack back into itself, so that it can be used as an additional modulation source.

Furthermore, I want to sequence 4 separate mono synths with the OT.

Connections:
OT midi out to midi in.
OT midi thru to synth 1
Synth 1 midi thru to synth 2
Synth 2 midi thru to synth 3
Synth 3 midi thru to synth 4

Settings:
OT: reserve midi channels 1 to 9
Synth 1 midi channel 10
Synth 2 midi channel 11
Synth 3 midi channel 12
Synth 4 midi channel 13

This is to make sure that each midi channel controls only one synth/audio track

Is this right?

Looks valid. In that scenario you must also set 4 audio channels to midi channels 10 to 13. Otherwise you will experience midi feedback on those channels. The audio tracks will block the midi tracks from receiving midi so the feedback loop is interrupted using this method.

1 Like

Could you please tell me more about this? I’ve figured that my channel routing would prevent MIDI feedback.

Receiving MIDI
OT Audio Track 1 : Channel 1
OT Audio Track 1 : Channel 2

OT Audio Track 8: Channel 8
OT Auto Channel: 9

External Synth 1: Channel 10
External Synth 2: Channel 11
External Synth 3: Channel 12
External Synth 4: Channel 13

Isn’t this routing enough?

Manual, section 8.6.4:

CC DIRECT CONNECT is activated/deactivated by pressing [YES]. Two settings exist.• ON will, when the Octatrack MKII MIDI mode is activated, route MIDI CC messages straight to the MIDI output port. When MIDI mode is enabled and LIVE RECORDING mode is active, specified CCs in the CTRL 1 and CTRL 2 SETUP pages can also be recorded by the sequencer. Other CCs will not be recorded by the Octatrack MKII, but still routed to the MIDI output port.• OFF makes the auto channel listen to MIDI CC messages according to the MIDI MODE MAP-PINGS table found in “Appendix C: MIDI CONTROL REFERENCE“. MIDI CCs 36-45 sent on the auto channel will be remapped according to the CC messages specified in the CTRL 1 and CTRL 2 SETUP pages.Messages received on the MIDI channel of the active MIDI track always behave as if CC DIRECT CONNECT is activated

section 15.2

If an audio track and a MIDI track share the same MIDI channel, the MIDI track will block the audio track from sending out data while the audio track will block the MIDI track from receiving data.

In other words: in your scenario, what goes out, will come back in , and what goes in will come back out and in…and out …and…freeeeeze unless you filter stuff in between or block incoming midi by setting the audiochannel midi assignments accordingly

1 Like

Thanks for your explanation, @roadmoviemusic. I’ve read it again and again but I’m still not piecing things together. I’m also new to MIDI CC and MIDI feedback stuff like that so I’m still quite lost on this. Thanks for your patience.

The Octatrack’s 8 audio channels are automatically set to MIDI channels 1 to 8, with the auto channel set to 9. So MIDI channels 1 to 9 are already used. 10 to 16 are left for my external synths.

You said to set 4 audio channels to midi channels 10 to 13. Do you mean OT Audio tracks 1 to 4 (setting OT Audio channel 1 receiving MIDI from MIDI channel 10, OT Audio Channel 2 receiving MIDI from MIDI channel 11 etc) ? And does that mean my external synths have to set to MIDI Channels 1, 2, 3, 4? I think I’m completely missing the point here with those questions.

I’m going to spend this weekend learning more about this:

  • Using the OT with just MIDI loopback
  • Using the OT with just the 4 external synths, no MIDI loopback
  • Using the OT with both MIDI loopback + 4 external synths

I’ll create a project that sends MIDI from the OT to itself (to modulate parameters) AND sends MIDI (notes and CC) to my external synths to see if I crash the OT. Would that be a good first step?

Cheers.

What @roadmoviemusic meant is that you need to set the midi channels of 4 audio track (for example track 1-4) to the MIDI channel 10-13.

But that’s not all, because when you do this track 1-4 will react on the MIDI data you sent to the external synths, too.

There are two settings which controls how OT audio tracks reacts to MIDI: “audio note in” and “audio cc in”. With these settings you can enable/disable if audio tracks reacts to note and cc data.

But these settings are global, which means either all audio tracks reacts to midi notes/cc or none. So combining direct loopback and external synth(s) control via MIDI thru is almost always quite restricted in some way.

2 Likes

Thanks for that @tnussb.

1 Like

I’ve had my first go with MIDI loopback (no external synths tho) and everything worked as planned! Automating scene changes and using the MIDI ARP to automate pitch changes has been fun. Will now try incorporating external synths as well.

Just when I thought I couldn’t be more impressed with the depth of this machine, the Octatrack proves me wrong time and time again.

Thanks again @roadmoviemusic and @tnussb

2 Likes