Question / Help Channel 3 and 4 not registering from Scarlett Focusrite 18i6


New Member
Hi guys,

I'm really new to all this! essentially i want to be able to livestream musical playthrough's with 3 instruments (plugged into seperate channels on my focusrite) and have a microphone plugged into the 4th channel for a Q&A afterwards, i've managed to run everything thing from: Focusrite -> Blackhole -> Logic Pro -> OBS. The first 2 channels on my interface work fine but i can't seem to get the others to work, any help would be massively appreciated, cheers!


New Member
I had the same problem, except with a Behringer UMC1820. My guess is that the OBS program is not built to handle more than two input channels from an audio interface. So here was my solution, though it takes some extra equipment.

First, I used MainStage to process the signals from all eight channels on the UMC1820. Then, I set the audio output as the UMC1820 and used a 1/4" TS to 1/8" TRS Y-cable to route the signal into a second computer running OBS, because the computers I have access to were not powerful enough to run both OBS and MainStage simultaneously. On the second computer, I set the input in OBS to take the incoming audio from the 1/8" jack, and it worked perfectly.

Depending on what equipment you have access to and what your audio needs are, there are many variations on my setup that you could try. If you have a more powerful computer than I do, you may be able to run OBS and MainStage together and simply output MainStage to BlackHole and then set BlackHole as an audio input source in OBS. If you don't want to use MainStage, I'm sure there are other programs that could be used, such as LoudLAB SoundDesk. I think that Logic Pro X would also work, though it probably is more difficult to use for live mixing. Finally, if streaming in stereo is not a requirement for you, a Y-cable is unnecessary.

I hope this helps!