Left/Right volume imbalance on mixer from audio interface

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Left/Right volume imbalance on mixer from audio interface

Post by revyth »

Hi! I have an RME UCX audio interface connected to a stereo track on a Mackie 802VLZ4 mixer via 2 balanced TRS cables. I’ve noticed that, strangely, the left channel volume is slightly lower than the right channel.
At first, I thought it might be an issue with the audio interface’s outputs, so I tried swapping the cables on the mixer (left to right and right to left), but the imbalance remains the same (left channel lower, right channel higher).
I’ve tried using different cables and even the other stereo track, but the problem persists. What do you think could be causing this?
Would it make sense to use the pan knob on the mixer to correct this imbalance?
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Re: Left/Right volume imbalance on mixer from audio interface

Post by forumuser660732 »

Have you checked that there is actually a volume difference between the output channels of the mixer? You can do this by routing them back into the RME and checking levels on the computer. It may well be an issue with the VU meter calibration on the mixer. LED levels aren't terribly accurate. Even if they are calibrated well, a very tiny imbalance with levels near the threhold for the next LED can make one turn on for one channel and not quite turn on for the other.

Another thing to try is to plug the RME outputs into Line in 7-8 and see if that is giving you an issue. Also, plug only 1 RME output into a mono channel (1 or 2) and see if you still get an imbalance at the output.
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Re: Left/Right volume imbalance on mixer from audio interface

Post by revyth »

It seems to be a known issue of this mixer model, left channel is always 1.7 dB lower than the right....not good :thumbdown:

https://gearspace.com/board/geekzone/13 ... lance.html
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Re: Left/Right volume imbalance on mixer from audio interface

Post by Sam Spoons »

Assuming you mean the issue stays on the left mixer channel when you swap leads the the issue is, as everybody says, with the mixer so follow the advice given to see if it's just the metering or is the actual signal level.
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Re: Left/Right volume imbalance on mixer from audio interface

Post by Hugh Robjohns »

As above ^

It's a known issue with the vlz4 generation of mixers and it's due to Mackie's custom 'Onyx' dual op-amps which have built-in mis-matched gains between the two sections.

From what I've read, Mackie seem to think this design error is acceptable, and I dare say most users either dont notice or don't care. Personally, I'd return the desk as being completely unfit for purpose....

But if you don't want to do that you can bodge a fix by offsetting the stereo balance control.
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Re: Left/Right volume imbalance on mixer from audio interface

Post by Arpangel »

Hugh Robjohns wrote: Wed Dec 11, 2024 6:00 pm As above ^

It's a known issue with the vlz4 generation of mixers and it's due to Mackie's custom 'Onyx' dual op-amps which have built-in mis-matched gains between the two sections.

From what I've read, Mackie seem to think this design error is acceptable, and I dare say most users either dont notice or don't care. Personally, I'd return the desk as being completely unfit for purpose....

But if you don't want to do that you can bodge a fix by offsetting the stereo balance control.

I have a VLZ4 and it does just this, I fix it by offsetting the stereo balance control.

:)
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Re: Left/Right volume imbalance on mixer from audio interface

Post by revyth »

Guys do you have an alternative mixer to recommend?

I don't trust this Mackie mixer, the issue is nonlinear meaning that the imbalance is not costant, so a simple offset of the PAN won't solve the issue if you change the gain/volume on the channel or the master.

I need something compact, low noise and good sounding. No need for FX
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Re: Left/Right volume imbalance on mixer from audio interface

Post by Wonks »

How many mic inputs and how many line inputs do you need? How many aux outputs? Do you want faders or are you OK with knobs?

What sort of EQ? Semi-parametric mids or fixed mids or no mids?
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Re: Left/Right volume imbalance on mixer from audio interface

Post by James Perrett »

I've been playing with a few small mixers this week and I'd go for something from the Allen and Heath Zed range if I was looking to buy one now.
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Re: Left/Right volume imbalance on mixer from audio interface

Post by Wonks »

I'd probably be looking at the Allen & Heath ZED range, definitely great quality mixers (which is why they aren't the cheapest) but check they offer the facilities you want.
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Re: Left/Right volume imbalance on mixer from audio interface

Post by Aled Hughes »

revyth wrote: Thu Jan 16, 2025 9:20 pm Guys do you have an alternative mixer to recommend?

I don't trust this Mackie mixer, the issue is nonlinear meaning that the imbalance is not costant, so a simple offset of the PAN won't solve the issue if you change the gain/volume on the channel or the master.

I need something compact, low noise and good sounding. No need for FX

Are sure that the imbalance is not constant, and that you're not being tricked bye fact that the LED meter scale is not linear? It offers finer metering detail around the 0 mark, so any imbalance will be visually more obvious there (if you understand what I mean - the step between the 0 light on the meter and the next one down is -2dB, which would show the 1.7dB imbalance. If you look at the -20 light however, you'll see that the next light down is -30 : a 10dB step, which would not show the imbalance.

I have the smaller 402, and now that I think of it, this has happened fairly often for me too - I've always put it down to "something else", because I tend to use it as a little problem solver and it gets plugged in at the last minute between different things to do a different job every time. Now I know, so thank you!

Out of interest, what is the purpose of the mixer in this setup? Can the RME not do what you need by itself?* I noticed from your picture that the only input connections were from your RME - was this set up just to demonstrate the problem?

*I'm aware that a lot of questions here about mixers are met with "Why do you need a mixer?" answers, so my apologies for not directly answering your question.
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Re: Left/Right volume imbalance on mixer from audio interface

Post by revyth »

I use[d] it both in studio and for live performance. Sometimes there are other people performing with me and a compact mixer like this comes in handy.

Your consideration of the non linearity of the fader makes perfect sense, I didn't think about that. To check if the imbalance is constant or not I should measure the output voltages L/R of the mixer but I don't have the right tool, maybe I should get one
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Re: Left/Right volume imbalance on mixer from audio interface

Post by revyth »

Wonks wrote: Thu Jan 16, 2025 9:28 pm How many mic inputs and how many line inputs do you need? How many aux outputs? Do you want faders or are you OK with knobs?

What sort of EQ? Semi-parametric mids or fixed mids or no mids?

4 mono + 2 stereo is sufficient, standard eq with low/mid/high is ok, 1 aux at least (2 is better). Knobs are ok if it makes it more compact
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Re: Left/Right volume imbalance on mixer from audio interface

Post by revyth »

James Perrett wrote: Thu Jan 16, 2025 9:34 pm I've been playing with a few small mixers this week and I'd go for something from the Allen and Heath Zed range if I was looking to buy one now.

Very good suggestion thank you, the Allen & Heath ZED-10 seems a good fit!
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Re: Left/Right volume imbalance on mixer from audio interface

Post by Sam Spoons »

Allen & Heath Zed 10 is a good choice, they are excellent little mixers.
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Re: Left/Right volume imbalance on mixer from audio interface

Post by ef37a »

revyth wrote: Fri Jan 17, 2025 7:45 am I use[d] it both in studio and for live performance. Sometimes there are other people performing with me and a compact mixer like this comes in handy.

Your consideration of the non linearity of the fader makes perfect sense, I didn't think about that. To check if the imbalance is constant or not I should measure the output voltages L/R of the mixer but I don't have the right tool, maybe I should get one

You can measure the output of any audio device with practically any Digital Multi-Meter and sine tone signals which any DAW can generate. Don't rely on DMM readings for frequency accuracy beyond about 400Hz. The meter will give you a readout in volts or mV and you can plug that into one of many "V to dBV/u converters online. Don't have a DMM? 'King get one, don't know how some of you musos get by without! Pay about £25.

My son has a ZED10 and uses it in conjunction with a MOTU M4 and loves it.

Dave.
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Re: Left/Right volume imbalance on mixer from audio interface

Post by ajay_m »

these are brilliant little things https://www.ebay.co.uk/itm/266494015054 ... ce40382255

This one comes with the wall wart (some of the listings don't include this). For looking at audio waveforms and measuring stuff they are nifty little things for under £30.
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Re: Left/Right volume imbalance on mixer from audio interface

Post by James Perrett »

revyth wrote: Fri Jan 17, 2025 7:57 am
James Perrett wrote: Thu Jan 16, 2025 9:34 pm I've been playing with a few small mixers this week and I'd go for something from the Allen and Heath Zed range if I was looking to buy one now.

Very good suggestion thank you, the Allen & Heath ZED-10 seems a good fit!

The Zed-10 was the one that I was using. Everything seems sensibly laid out on it and the sound is good. The only thing missing is effects - but then that's why the Zed-10FX exists...
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Re: Left/Right volume imbalance on mixer from audio interface

Post by revyth »

ajay_m wrote: Fri Jan 17, 2025 12:27 pm these are brilliant little things https://www.ebay.co.uk/itm/266494015054 ... ce40382255

This one comes with the wall wart (some of the listings don't include this). For looking at audio waveforms and measuring stuff they are nifty little things for under £30.

Thank you, very useful!
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