Help with strange clipping on vocals takes

[Korwent]

Hi everyone, I'm currently in the process on receiving vocal tracks for a project I'm working on, and I find myself facing a strange problem : the tracks keep clipping at -4fB, except occasionnaly where it works just fine!

Here's an example :

I added the blue rectangle to show you where it clips.
The clipping is symmetrical and there is no DC offset on the tracks, so that's not the problem.
They recorded it on a Focusrite Scarlett 2i4, and assure me they did not move the gain during tracking anywhere, nor did they changed the gain of the tracks afterwards...

I told them that to rerecord the tracks lower, but it might still be a problem if they don't record low enough and some splikes still get cut off, and anyway I'm really wondering what could cause that?

Does anyone have thoughts on that?

 

[MrBongo]

is it really going over -4 , or is it intersample peaks shown by your DAW?
Sometimes a few peaks can overshoot a limiter when they´re too fast.

Ask your client which limiter has been used and why, or why they clipped the AD converter. Whatever fits the best

 

[Korwent]

Nope it's really going over -4dB, obviously the first thing I thought about was the attack of a limiter that was too slow to stop fast transients, but there was no limiter in the chain, and if they clipped the converter there would be no signal over the -4dB...

 

[henryjarv]

.......Broken cable....Maybe.....?

 

[Korwent]

Well it wouldn't really clip that way with a broken cable...

 

[Nikolas Quemtri]

Could you show a closer view of the waveform? I'd like to see how it clips, showing a trimmed waveform on a higher zoom value.

 

[Korwent]

No problem, her's what it sshows when zoomed in on a few periods level:

And zoomed in on avout a period level :

As you can see, it really looks like digital clipping as the spikes aare really getting cut off!

 

[KillFrenzy]

I know it's a long shot, but is it possible there is a calibration problem somewhere along the way? It looks like digital clipping, as you described. The weird part is that you have peaks above -4dBFS.
I think you got a defective unit, man.

 

[Nikolas Quemtri]

The weird part is that you have peaks above -4dBFS.

I agree.
The only thing I may suggest is to use some Declipper plugin (e.g., iZotope RX) to fix the recorded material.

 

[Korwent]

Well it's not my unit, and the guys are 700km from where I live so troubleshooting is quiiiite difficult...
Of course the weird part is there are spike that go beyond what seems like digital clipping, that really makes no sense to me (I'm graduating in electronics/signal processing and parts of my degree are converters etc, so I really thought about it before asking), Fortunattely they were able to rerecord, I just told them to do it at a lower level, which solved the problem obviously, but I'd have liked to understand WTF was going on here!
Musy be the vconverters in the unit, but in that case -4dB is a really weird clipping value...