OBS sees input from MOTU M4 channel 1/2 only, not 3/4

OBS receives audio from the M4s inputs 1 and 2 just fine, but not 3 or 4. I cannot find any relevant settings to change, everying OBS is just generic "M4" without specifying any inputs. Is OBS effectively hardwired to inputs 1/2? Everything is seeing signal except OBS it seems.

Is there anything I can do? I wasn't able to find anything on Google or searching here.

I'm on Monterrey with the latest OBS version and MOTU drivers. Thank you.


Active Member
I'm surprised you don't have all 4 inputs mashed into one stereo source. That's usually how OBS works, with no option to change it. That's not so useful either.

Generally, OBS audio is not very sophisticated at all. Yes, it has Filters, and it tries to be somewhat useful, but the I/O problems keep it only useful for a USB mic, consumer stereo card, or a finished loopback from a DAW. It can't select channels from a multichannel device, but instead takes all 32 tracks from a mixing console, for example, as 16 stereo pairs to downmix into a single stereo source, and THEN lets you try to salvage something from that mess...when probably all you wanted was the first 2 or last 2.

Back to your example, don't even try to get 4 mono sources from a 4-input device in OBS. Use a DAW for that. Do all your processing in the DAW, then connect the finished soundtrack to OBS to pass through unchanged.


The M4 comes with licenses for a couple of DAW packages, but I found them to be overkill and too complicated for my needs, which was just controlling the relative levels of all four inputs from the M4 and getting them into OBS. I found that SoundDesk from Loudlabs works great for that -- it's a much simpler DAW that's really just a mixing console, and it includes a virtual audio driver that lets you export the output channels to OBS. You can set up one channel for each M4 input (or two stereo pairs), and then output that mix to the virtual driver. It's well worth the $30 it costs.

What's really nice is that it also provides a matrix for assigning the audio output from every running application to any of the 32 input channels, so you can mix those into your output as desired. It also lets you assign output from each channel to any of the 32 channels in the virtual driver and any real output -- that doesn't help with OBS input since it only sees the first two, but it lets me set OBS output (as an input to SoundDesk) to the M4 1/2 output for monitor, while I'm sending recorded music to the M4's 3/4 out into my PA system.