Left channel disappearing from stereo input bus


I use the Steinberg UR242 and a Yamaha S70XS synth with I’m using Cubase 8.5.30, latest version of 8.5 on Windows 10 64 bit.

It’s related to hearing the audio from a MIDI track driving an external instrument, or rather, hearing it in full stereo (not it’s pure MIDI, not modeling . I have used this last year no problem at all (albeit on an earlier version of Cubase, 8.0 and 8.1).

To hear my MIDI tracks play, I have a monitored audio track taking the stereo input bus, configured to take 3 & 4 on the UR242 which in turn is fed from the Yamaha outputs and routing this input bus to the stereo output bus in Cubase which is configured to use outputs 1 & 2 on the UR242 which I can hear on both my speakers and headphones.

Having mainly worked purely in pure instrument tracks for the last year, I’ve opened up some old projects where I was using my Yamaha XS70 on MIDI tracks, and now I’m getting no stereo audio from any MIDI tracks at all, I only get mono on the right side. It definitely used to work perfectly. All VST tracks are perfectly fine, full stereo.

Now when I use the Yamaha in local mode, I get stereo no problem through the UR242 with Cubase shut down. It’s only when being driven from Cubase that the problem arises. This is no matter what the instrument is selected on the Yamaha there’s no panning on the mixer in any tracks in Cubase so not getting anything on the left is not due to that.

As I say if I switch to local mode, I get full stereo so the Yamaha outputs stereo audio no problem and the Yamaha receives and outputs MIDI notes in all cases.

If I create a mono input audio bus from UR242 input 4 which is taking the Yamaha right output, and use that instead of the stereo input bus, I get the mono signal in both speakers, all coming from input 3 effectively, the left one. If I create another similar mono input bus for UR242 input 3 coming from the Yamaha left output, and do the same, I get nothing at all. So it’s like in stereo mode, input 3 on the UR242 is completely left out.

Now interestingly, if I pull out the right audio cable out of the back of the Yamaha, i.e. input 4, I can hear in the left side from just the single remaining cable for the left output, i.e. input 3, but when I put back in the right cable, the left audio disappears and only the right can be heard (again this does not happen in local mode, I can hear both so there’s nothing wrong with the Yamaha outputs or the cables.

So it’s like Cubase is turning off one of its inputs, when the other input is present, when using an audio stereo input bus?

As well when you press a key on the keyboard you can see only one side of the stereo signal on the audio track is moving in the mixer, the right one, so it definitely appears that the issue on the audio input bus, and not in the routing of that audio to the stereo output bus.

I’ve created a brand new project in 8.5.30, still the same. I’ve done reboots of all the equipment, makes no difference.

Any help appreciated if anybody has encountered anything like that or could suggest something to try that I have not.


Just a quick thought to try…

Make sure the audio track you are using is a stereo audio track. Not a mono audio track.

I do know that using a mono audio track somtimes messes with the sound of stereo VST effects. Maybe it is somehow associated with this issue too.

Regards. :sunglasses:


Yes it is a stereo audio track, as in the input bus is one configured for both left and right.



Just want to make sure… you did state your input bus is configured as stereo. Good :wink:

I’m asking if the Cubase audio track you are using is a stereo or mono track? Make sure it too is stereo. You might be feeding a stereo bus thru a mono audio track.

Regards :sunglasses:

Do you get the same behaviour using inputs 1/2…maybe the problem is in hardware or in the settings of the UR rather than in Cubase.

Make sure loopback is disabled in the interface, make sure nothing in Cubase is routed to one of these inputs somehow and it’s stopping a feedback loop from occurring. Make sure you have no dspFX loaded in the UR.

EDIT: Sorry…reading again I see that can’t be the case if the keyboard plays in stereo set to local…so to be clear…you play the keyboard in local mode and hear stereo?
Then you switch to local off and play from midi without changing anything else and you get one side only??

Hi yes it is indeed a stereo audio track, the default. In fact, if you create a mono track, you can’t select any stereo bus as an input and when you feed it to a stereo output bus, you do get the same mono signal in both ears as expected.

Now interestingly I just tried creating a new mono audio track (and disabling the stereo one), when I select Mono input 3 as the input bus, the left, I get nothing, and if I select input 4, the right, I get the mono signal in both ears. Which is consistent as before. And it shows that whether I use a stereo input bus or a mono input bus, either way, input 3, the left is not making to the stereo output bus through Cubase and the UR242 when combined.


Hi, yes , that’s correct. When I take Cubase out of the picture by shutting it down, and just play the synth through the UR242 in local, I get proper stereo no problem at all. So hardware wise, the signals are getting all the way out of the synth, through the UR242 and finally to my headphones (plugged into the UR242, not the synth).

So the problem seems to be in software somewhere.


Ahh…you mean with the UR in standalone rather than with the keyboard in local mode. This was confusing me.

Can you post a screencap of VST connections inputs.


Sure can, please find attached. And thanks for your assistance, btw, and also to PRock.

Inputs 3 and 4 on the UR242 go in the back, inputs 1 & 2 are the mic inputs at the front, which can also be plain audio leads as well, I don’t currently use them.

So I’m using Stereo In 2 as my audio input bus effectively on my stereo audio track.

VST Connections Inputs.jpg

BTW, just for the elimination of doubt, I changed the synth cables from inputs 3 & 4, to inputs 1 & 2 at the front, and switched the audio input bus to Stereo In 1, same problem, only audio in the right channel.

Try to de-assign 3&4 from the mono input bus.

I hope Grim’s suggestion helps and that’s it. :wink:

But, I will mention this long shot thought about the physical connections from the keyboard to the UR.

Sounds like you are using audio connections from the keyboard to the UR through the 1/4" jacks. Is it possible that you are using a TRS (stereo) versus a TS (mono) cable at one or each jack connection? Maybe that could cause this?

Regards :sunglasses:

It’s covered in the UR manual though is really unclear (quoted below)…but given the result OP is seeing it almost makes sense :wink:
Simply put: If you assign the same output to multiple buses only the upper one in the list is working.

When the same plural input port is assigned to the
device port, the only [HARDWARE] listed upper in the
device port is shown in the channel.
In this example, the only [HARDWARE] for Stereo bus
is shown in the channel. Change the settings at Stereo
bus to [Not connected] or assign an input port other
than [UR242 Input 1] to be shown as the
[HARDWARE] for Mono In bus.
For the Stereo bus, set the combination [UR242 Input
1] and [UR242 Input 2] or [UR242 Input 3] and [UR242
Input 4] to be shown as the [HARDWARE].
[HARDWARE] is disable for other combinations.