Clipping issue. DJ mixer>Behringer UCA222>Macbook Pro

Been trying to troubleshoot by myself for a month, on and off. I’ve checked the Audacity manuals, FAQs and forum searches, made some changes, but no change to my problem.

I have recorded fine to PC, as the Mic Input level can be adjusted down.

However, running into my Macbook Pro, with no line level adjustment available, regardless of how low I have the signal, as soon as I open both channels on the mixer when mixing two tracks together, the DAC cannot handle it and there’s a clipping sound.

It is not ‘pops’ on the records.

I am using the dedicated ‘Record’ output on Allen & Heath Xone 22 Mixer, which has (Nom./max.) RCA: -10 dBV / +10 dBv

I’ve also tried using the ‘Monitor’ output which has (nom./Max.) of RCA: -2 dBu / +18 dBu and still have same problem

Please see photo and attached .wav file for example

Does anyone else have this issue and have you found a solution?

Screen Shot 2020-01-04 at 7.55.07 PM.png
Zoomed in
Screen Shot 2020-01-04 at 8.11.56 PM.png

As a test, do you have a CD or cassette player that you could connect directly to the inputs of the UCA222?

Another test variation: temporarily reverse the left and right RCAs at the UCA 222.

Just post the WAV test sound file. We can make graphics from that.


That’s weird! It looks something like static discharge. I’d guess it’s on the analog side.

Another couple of experiments/questions - Does it happen with nothing plugged into the UCA222?
Can you hear it from the mixer’s analog output (line or headphone output)?


FYI - It’s a noise spike, not clipping.
[u]Clipping[/u] is “overload distortion”. You get clipping if you try to push your analog-to-digital converter (recording) or digital-to-analog converter (playback), or WAV file,over 0dBFS or if you try to get 110 Watts out of a 100W amplifier, etc.

But yes, a large/loud noise spike can push the levels into clipping and that’s happening to you.

I don’t think so - at least, not entirely. The initial spike is instantaneous, which would be unusual for analog, and then after one of the spikes is a “jitter” of alternating high/low samples. The “jitter” looks like a digital problem. I’ll bet that the problem occurs before the signal gets to Audacity, but we need to trace the fault back to see where it originates.

It looks like a profoundly unstable right channel. If someone paid you to make a normal consumer digital system do that, what would you do?

On the other hand, it only happens with specific mixer settings.

I can feel…pressing fingers to forehead…two different problems.


How about DC Offset in one channel of the mixer driving the UCA222 nuthouse? This will show up instantly when the poster reverses Left and Right inputs on the Behringer.


Thanks for the suggestions everyone.

I’ll try them after work tonight and provide audio samples.

  • this shows the signal noise (about -82 db) from mixer into UCA222 with the faders on ‘0’ - I’m guessing this is just from the UCA222 being on ‘full’ due to no volume control on Mac? Or the signal from the needles? Is this noise a problem, or contributing to the problem?
  • I’ve swapped the L/R RCAs into the UCA222 as per Koz recommendation. I’m not able to reproduce the noise spike reliably. So, maybe that’s fixed it? I’m not sure? Do I also need to swap L/R on the mixer output? Or is it a moot point when running stereo into the UCA? If someone can explain how/why that may have fixed it, that’d be handy just for my knowledge of signal paths, DC offset etc.

No, that’s not a problem. It’s normal for there to be a tiny bit of noise from any audio device. That “silent” sample shows a little bit of “mains hum” plus “dither noise”. With a bit of careful tweaking and better quality cables, it “may” be possible to reduce the noise level a little, but probably not worth the effort as the noise is already pretty low.

Try swapping them back again and see if the problem reappears.

If that has fixed it, then my guess would be that the problem was due to dirt on one of the connectors. The act of unplugging and plugging in again may have cleaned the contacts sufficiently to cure the problem.

Bummer, it’s still happening randomly and intermittently
Screen Shot 2020-01-06 at 8.54.47 PM.png
Any other ideas?

Which way round are the leads?

That is one possible but unfortunate result from reversing the leads, you get a third condition.

Condition 1 - The noise appears on the right channel.
Condition 2 - The noise appears on the left channel when you reverse the leads.
Condition 3 - The noise vanishes (or appears to) when you reverse the leads,but then comes back when you flip them back.

Correct me anywhere.

So you have 1 and 3.

Back up the thread a bit, Steve asked you if you have Something Else you can plug into the UCA-222 in place of the mixer. Do you?


Which way round are the leads?

I know it doesn’t seem so, but we’re doing statistical analysis (across multiple time zones), so don’t leave anything out.


Which way round are the leads?

In my o.p. the leads were correct R/L.

In my two posts from last night the leads were reversed into the UCA, so L going into R, R going into L.

Condition 2 - The noise appears on the left channel when you reverse the leads.

No, it only seems to distort badly on the R channel. Sometimes minor in the L, but R channel is where it shows up, regardless of which lead is in the UCA.

I’ll test another few sources tonight into the UCA tonight - CD player and Laptop.

I don’t think I have another RCA cable I can test with unfortunately. However, I tend to think it’s the UCA conversion or source volume rather than the cable. Could be wrong though.

This seems to have fixed the problem as I can now reduce the gain on the UCA input

I tested a CD player direct to UCA and the spiking persisted, so I think the lack of gain adjustment on the UCA/Mac input was the issue.

I’ll keep experimenting and report back if I learn anything else

Aha, I think I’ve finally ID’d the problem:

The Left channel bleeds into the Right channel

This is a recording with one RCA into Left channel

I tested with one RCA in Right channel and there’s no left channel signal

So when they’re both plugged in, the Right channel is spiking because it’s getting bleed from the Left channel too

So, I think I need a new DAC, right?

Before we jump to conclusions, just one thing. Did you disconnect the right channel from the UCA222 at the Behringer end (nothing plugged into the UCA222 right input connector), or at the other end of the lead (cable plugged into the UCA222 but other end of the cable not plugged into anything)?
If it’s the latter, please repeat that test with nothing at all plugged into the right channel of the UCA222.

One other thought - unlikely but may be worth checking if the problem is repeatable with nothing at all plugged into the right channel of the UCA222:
Try wiggling the Monitor switch on the UCA222 to ensure that the switch isn’t causing crackling. Check that the problem is reproducible for both monitor on and monitor off.

The UCA 202 (and its cousins) do a mono mix at the headphone connection. If there’s something wrong with that service (headphone connection or the switch) it can cause channel cross conditions.

It’s rough to believe the cross only goes one direction…

You have a unicorn problem. There are several Behringers in the sound of my (digital) voice and none of them have ever, to my knowledge, failed. Behringer cranks out quality products (I have several), and that’s why we’re giving you odd looks when you had one that apparently failed. Plus, it failed in a very wacky way.

Did you buy the UCA222 new? Why did you get the red one? Most people opt for the plain gray 202.


That’s not ordinary clipping, by the way. It may be volume-related, but you are not just running out of volume range.