SI Impact - FX returns on stereo mix buses: left channel only

JasonVMX

Hi,

I'm new to the forums so let me know if this needs to be placed elsewhere.

My church purchased an SI Impact recently and, to my knowledge, I'm using it with the default setup. I use one of the stereo mix buses to send audio to a PC, for our livestream. For some reason, the FX returns only seem to play out of the left channel on this stereo mix bus. Has anyone encountered this? Or does anyone have any suggestions of things to check?

I send the FX return to the mix bus pre-fade, as we don't want reverb in the main FOH mix but we do want it on the stream mix. When I SOLO the FX return, I hear it in both monitor headphones. But when I monitor my whole stereo mix bus, I hear everything centrally apart from the FX which I only hear in the left headphone.
I have verified on the PC that it is only receiving FX on the left channel, all other sources come through correctly as a stereo signal (I can pan mono sources correctly, and other stereo sources work).

I have never really used the pan knob, so the FX return is not panned to my knowledge. The FX returns are stereo, and as I think is the default, I have stereo channel ST5 patched to LEX-RT1 and LEX-RT2, ST6 to LEX-RT3 and LEX-RT4 etc.

Any thoughts welcome!

Thanks,
Jason

HARMAN_Tder

Could be hardware/DSP issue but you should check Pan setting on Stereo 5-8. However if they all seem to be doing it then it seems like there may be an issue with the mixer. As a test I would save my show to the internal drive and back it up to USB as well. Then under Menu>System Choose reset all. Plug in a mic to a channel and route the channel to LR and then add FX to it and see if the return is coming back into both the Left and Right sides.

If it seems to work then it would indicate likely some sort of user error or much less likely an issue with the show file. If it still does it then it would point towards an issue with the console

JasonVMX

@HARMAN_Tder said:
Could be hardware/DSP issue but you should check Pan setting on Stereo 5-8. However if they all seem to be doing it then it seems like there may be an issue with the mixer. As a test I would save my show to the internal drive and back it up to USB as well. Then under Menu>System Choose reset all. Plug in a mic to a channel and route the channel to LR and then add FX to it and see if the return is coming back into both the Left and Right sides.

If it seems to work then it would indicate likely some sort of user error or much less likely an issue with the show file. If it still does it then it would point towards an issue with the console

Thanks for the quick response, I will give this a go at the weekend hopefully.

JasonVMX

An update on this - I did a "reset all" as suggested. From the default patching, I was able to create a very related issue.

I set a mix bus to stereo, and by default all mix sends were global post fade (therefore the master fader for the mix bus was green). With this default configuration, a mono source was working as expected.

I then changed the mono source to individually be post EQ (turning the fader for that mono channel yellow). This is when I experienced the issue - only the left channel of the stereo mix bus worked as expected. The right channel seemed to still behave as if the mono source was post fade.
So with the channel fader shut for the main mix, and open the for stereo mix bus, the mono source only appeared on the left channel of the stereo mix bus. With the fader half open for the main mix, the mono source then appeared at half volume on the right channel of the stereo mix bus. Of course, the expected behaviour was that the mono source would appear on both left and right channels of the mix bus, with the main mix fader having no effect.

Interestingly, the issue seemed to invert itself if I set the global mix sends setting for the mix bus to global post EQ (turning the master fader for the mix bus yellow). At this point the mono source appeared on both channels of the stereo mix bus correctly. But then if I changed the mono source to invidiually be post fade, it appeared correctly on the right channel of the stereo mix bus, whereas the left channel of the stereo mix bus still acted as if the mono source was post EQ.

Throughout this testing the mono source was panned centrally.

So it really feels like there are bugs with mixing to a stereo mix bus - specifically, having some channels set to send to the mix differently to the default. Does this sound like a bug with the desk? Or perhaps it is still user error.

HARMAN_Tder

Just to confirm.. you're talking about stereo mix bus (as in aux send) not main stereo mix bus (i.e. main mix). There is a bug on stereo aux mixes. I need to confirm what it is but i believe it results in a bias to one side of a stereo mix.

This is a fairly high priority bug so hopefully we will get it fixed early this year but no promises.

JasonVMX

@HARMAN_Tder said:
Just to confirm.. you're talking about stereo mix bus (as in aux send) not main stereo mix bus (i.e. main mix). There is a bug on stereo aux mixes. I need to confirm what it is but i believe it results in a bias to one side of a stereo mix.

This is a fairly high priority bug so hopefully we will get it fixed early this year but no promises.

Yes that's correct, I am using "Mix 13" as a stereo mix bus, and when I mix to that bus I have issues if channels are sending to the mix bus from a different tap (post EQ, post fade etc.) to the global setting for that mix bus.

Thanks, I will keep an eye out for updates as this is likely related to the bug you've mentioned. For now I am using the mix bus in mono instead, as this is sufficient for our use case.