Left signal quieter than right signal on stereo channel

[MaximusParticipant]

Hello! I’m a volunteer at my church as part of the worship team and sound team (drummer life I suppose). I’ve been running into a few issues recently with the QU-32 that the church has. The one I ran into today that had me stumped is that the stereo channel we use to run sound from a computer to the board was seeing a higher level of signal on the right channel than the left channel. We tried switching the input cables from one channel to the other with no luck. When pulling cables out, I noticed that if I didn’t fully plug in the 1/4 cable into the jack it read full signal. The only thing I can think of that might be causing this is that the left input is set for mono rather than stereo, if that’s even a setting in the board. Any advice or where I would look to change the input mode for this channel would be greatly appreciated.

[SteffenRParticipant]

I guess your cable is broken….
that’s the case in 99% situations with this issue
at least I would start there with the search

[MarkPAmanParticipant]

Your desk has 2 stereo inputs using 1/4″ jacks. Check the cable on the other one.

Also check playing back a different track – i could be that the recording you re using in not balanced evenly between L&R.

[Mike CParticipant]

When pulling cables out, I noticed that if I didn’t fully plug in the 1/4 cable into the jack it read full signal.

That comment makes me think you have a balanced line wiring issue.

On the stereo inputs using the left channel only will feed as mono to both left and left outputs, plugging into only the right channel will only feed the right output, plugging into both left and right inputs will feed a stereo into in stereo to the left and right outputs.

I assume your just using the headphone jack output from the computer.

Are you taking that into an interface or a direct box type of unit?

Are you taking a 1/8 TRS inch cable that breaks out into two 1/4 inch mono
TS plugs?

Are you taking a 1/8 TRS cable that goes straight through to a 1/4 inch TRS
stereo plug?

If it is the 1/8 TRS straight through cable to a 1/4 TRS that is the problem and
would do what you said when only plugging the plug in part way.

The mixer 1/4 inch inputs are balanced line and plugging in a stereo TRS plug will result in a lot of signal level cancellation.

[MaximusParticipant]

The cable is an 1/8″ splitting into 2 1/4″ and I don’t think it’s the cable because we flipped the inputs each of the 1/4 were plugged into and still had the same problem. In addition I plugged them into one of the other sets of stereo channels and had the exact same problem. I can’t double check any of these things until Sunday when we’re back in the building, but I’ll bring an addition 1/8 to 2 1/4 that I have with my stuff to make sure it’s not the cable. And we’re just taking it from the computer directly into the board, no direct box or interface.

[volounteerParticipant]

@Maximus

Computer stereo is often not perfect and needs tweaking to achieve balance.

The original source may be unbalanced.

When recording the audio interface may be unbalanced.
My TT preamp fed an unbalanced signal to my PC. Vinyl off or preamp off? Anyway it unbalanced.

And your audio out can be unbalanced if you send analog not digital.
But digital may be too if the original source was unbalanced.

[MarkPAmanParticipant]

“I don’t think it’s the cable because we flipped the inputs each of the 1/4 were plugged into and still had the same problem.”
So the left side on the desk stays lower whichever way you plug the cables – this indicates that the problem is after the cable.

“In addition I plugged them into one of the other sets of stereo channels and had the exact same problem.”
If the cable is OK, as you seem to have proved, then there is either the same fault on both stereo channels, which is very unlikely, or there’s something else going on.

How do you notice the levels are different, by metering, in headphones, from main speakers?

So, check the pan (OK, balance as they’re stereo) on those channels.
Check the balance of the main output. Also any groups you may be routing this through.

[volounteerParticipant]

@Maximus

Have you tried other inputs on the Qu and gotten the same result?

It would help with a more complete and accurate description of how all these things are connected together.

[Mike CParticipant]

The cable is an 1/8″ splitting into 2 1/4″ and I don’t think it’s the cable because we flipped the inputs each of the 1/4 were plugged into and still had the same problem. In addition I plugged them into one of the other sets of stereo channels and had the exact same problem.

Just to double check does you cable look like the one in the attached picture?

If you go to a mono mixer channel and plug in one cable at a time while PFL’ing the channel how do the levels compare on the meter after setting the input gain the first time and then not changing anything after that?

For a test signal from the computer play some pink noise, you can find you tube videos
of nothing but pink noise.
Or go high tech and go to Meyer Sound’s website and download their test signal that is called “M Noise”

Use the test signal for channel level test.

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[MaximusParticipant]

I’ll have to check the cable in a mono input after service (it’s almost like people want to hear what’s going on). I’m monitoring the level from the processing screen on the board, in addition to it being an audible change in the speakers as well. I took a short video showing the difference, and the cable we have is the RCA one with 1/4″ adapters.

[MaximusParticipant]

Here’s a YouTube link. Apparently a 10 second video is too big to upload here.

[volounteerParticipant]

@Maximus

Still not enough information to not be guessing.
What is the complete signal flow you are having problems with?

That video might indicate a cable problem or it could be other causes.
Until we have a complete clear accurate description of all devices involved and the signal flow we can only guess.

Do you have compression on one of the stereo channels but not the other ?

[MaximusParticipant]

The cable goes straight from the computer into the board. As far as I know there’s no compression on the signal, however we do have the built in gate on it. We put the EQ from the board on the channel as well. I ran signal through the cable on a different channel and had the same overall amount of signal going through both sides of the cable. I would’ve taken a picture of the cable routing, but it’s a bit of a mess behind the board and live streaming setup.

[Mike CParticipant]

Let us know what you get when plugging into a mono channel 1/4 inch, plug in, note the
level, unplug that cable an plug in the other channels cable and see what you get.

Just to double check again try another audio source plugged into the same cable.
If you have a portable radio tune it to an off station and use the static for a test.

[MaximusParticipant]

Thank you for the suggestion Mike, I did that earlier today (granted I wasn’t using static or white noise) and I was getting line level on both ends of the cable.

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