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Waveform anomaly (sporadically) when recording to Logic

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Waveform anomaly (sporadically) when recording to Logic

Postby rushcutter » Mon Jan 25, 2021 10:06 pm

Hi all, first post here!

I've been living with this for years and editing my way round it but I recently signed up to SOS so I thought I would ask around the forum.

When recording to Logic Pro X via Behringer UMC22 USB interface on my Macbook Pro (Retina, 13-inch, Early 2015, Big Sur) I sporadically get a click/pop sound. The sound is definitely recorded as I can hear it during playback. When I zoom in to the click/s I can see something that looks like the waveform was recording fine but then a small square chunk of it was taken and flipped/inverted around the zero line.

This shows what I mean:

Image

When does this happen?
It is sporadic, as in I can go days without hearing it then get 3 or four on a track then in the same project I won't hear it again for days. Sometimes it happens multiple times in the same sitting.

Things I have tried, that seem to have not had any effect:
Macbook running on battery/plugged in to AC power.
USB cable replaced with half a dozen different cables.
Different USB interface tried (Behringer UCA222)
Disabled WiFi on the Macbook
Disabled Bluetooth
Disabled WiFi and Bluetooth
Quit Dropbox (runs on startup)
Various sources (guitar, synth, radio)
Dropped buffer setting from my usual (256) to 512 and 1024
I've Googled everything I can think of searching for
I've read numerous articles on clicks and pops in SOS which lead to me investigating mains appliances as a possible cause:
- Looked at timings of heating (boiler)
- disabled boiler and thermostat
- Tried shutting the fridge freezer off
- Switched off WiFi router

But still it persists...

Can anyone offer any ideas please?

thanks so much, I live in hope!

Christoph
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Re: Waveform anomaly (sporadically) when recording to Logic

Postby desmond » Mon Jan 25, 2021 10:30 pm

Do the Behringer interfaces support Big Sur officially? Problems like this are usually low leve, often driver-related or sometimes some other low level funkiness, assuming you're not stressing your system or Logic to the point of collapse.

Have you tried a different, non-Behringer audio interface? Even the inbuilt audio on your Mac? Do you still get the issue?
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Re: Waveform anomaly (sporadically) when recording to Logic

Postby rushcutter » Mon Jan 25, 2021 10:54 pm

Thanks Desmond for replying so quickly!

desmond wrote:Do the Behringer interfaces support Big Sur officially? Problems like this are usually low leve, often driver-related or sometimes some other low level funkiness, assuming you're not stressing your system or Logic to the point of collapse.

Have you tried a different, non-Behringer audio interface? Even the inbuilt audio on your Mac? Do you still get the issue?

I've had this for years, way before Big Sur, they are both coreaudio compliant.

When you say "other low level funkiness" is there anything else that springs to mind? I will try the built-in audio and see what happens there.

Thanks again.
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Re: Waveform anomaly (sporadically) when recording to Logic

Postby blinddrew » Mon Jan 25, 2021 11:13 pm

What else is plugged into your system? Is there anything giving a solid ground or are they all class II devices? Sometimes having no ground at all can manifest in little digital clicks and pops.
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Re: Waveform anomaly (sporadically) when recording to Logic

Postby rushcutter » Mon Jan 25, 2021 11:38 pm

blinddrew wrote:What else is plugged into your system? Is there anything giving a solid ground or are they all class II devices? Sometimes having no ground at all can manifest in little digital clicks and pops.

Start to finish currently I have:
Midas 14 mixer -> (passive) patchbay -> UMC22 usb interface -> macbook

UMC22 output goes to Adam T7v monitors

From what I can tell the Midas looks to be earthed, as do the Adams.

cheers
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Re: Waveform anomaly (sporadically) when recording to Logic

Postby paul tha other » Tue Jan 26, 2021 1:10 pm

i sometimes get things like that if i have to change bit depth in one session and forget to change it back when i open another ie recording 16 bits and 24 bit in the same session

the only way i found out was , i record at 24 bit at work and 16 at home.i had to do a couple of sessions when we first locked down where i was adding vocals at home..when i tried to flatten and merge the comps id get waveforms just like you are showing there
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Re: Waveform anomaly (sporadically) when recording to Logic

Postby CS70 » Tue Jan 26, 2021 1:22 pm

A wild shot.. looking at the picture, assuming the picture is a representation of the buffer contents as read by the DAW, and assuming that graphics calculation is not corrupted (which is a reasonable assumption, as it's nothing to do with the audio threads), it looks like the memory simply contains part of the waveform that was there just before.. memory doesn't get zeroed by a driver before being filled again because it would be a waste of cpu cycles, but it's just overwritten.

That would suggest that for a small period of time the computer was not capable of overwriting the buffer - perhaps due to the CPU not getting to do that in time or the USB I/O not being ready in time. Is there any occasional CPU spike in your system? Otherwise, it could be a USB problem - either hardware or software (audio drivers will have to rely on the transport drivers, in your case USB).
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Re: Waveform anomaly (sporadically) when recording to Logic

Postby rushcutter » Tue Jan 26, 2021 2:24 pm

Thanks everyone for the replies.

@paul no bit depth changing although very interesting that you get the same wave form shapes...

@cs720 I've monitored the CPU while the clicks happen and there are no spikes. USB is looking increasingly likely as I tried what Desmond suggested running the onboard audio.

Been switching back and forth every hour or so between USB Interface and onboard audio recording a sine wave. With USB there are occasional occurrences but with the onboard audio it has not happened at all so far.

I reached out to Behringer last night to see if they had heard of this before. One of the questions they asked was about whether I was using USB3.0 ports - they suggest using 2.0 where possible as there is no performance advantage using a USB3.0 port for this interface and USB3.0 ports can vary a lot more in terms of stability and performance.

Turns out my MBP only has USB 3.0 ports so I wonder if this is something to do with it... If nothing else it is a new lead for me to Google!

Thanks again everyone for the ideas so far. If I get anything definitive I will update here in case anyone else stumbles across this thread in future.

cheers

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Re: Waveform anomaly (sporadically) when recording to Logic

Postby Sam Spoons » Tue Jan 26, 2021 3:57 pm

USB3 is touted as being back compatible with USB2 so there is no reason, in theory, why it should cause problems.
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Re: Waveform anomaly (sporadically) when recording to Logic

Postby N i g e l » Sat Jan 30, 2021 1:21 am

can you post the actual recorded wav file with the anomaly, so that the actual numbers are available ?
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