Crackling at low latencies on M1 Mac, recording audio with no plugins

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Crackling at low latencies on M1 Mac, recording audio with no plugins

Post by claz »

Wondering if anyone has suggestions for this bugaboo:

I'm getting intermittent pops and crackles at low latencies on a machine that should be able to handle a decent workload at low buffers.

I need the low buffers for live overdubbing without latency.

Worse, the crackles end up in the recording; it's not just a monitoring issue.

Equipment:
- M1 Max Macbook Pro, 64GB Ram
- Motu M4, latest driver / firmware
- Mac OS 12.4
- Reaper 6.59 (also happens in Logic, seemingly less)

Test case:
- In Reaper
- Recording two audio tracks: a mono vocal and stereo piano
- No plugins
- 44.1kHz
- no other CPU intensive processes running in the background

Result
- crackles occur below a buffer of 1024 samples

I've done everything I can think to do (updates, checking connection, restarting), and it's driving me crazy!

Any troubleshooting/diagnostic suggestions appreciated.
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Re: Crackling at low latencies on M1 Mac, recording audio with no plugins

Post by muzines »

This sounds like driver issues to me - does the M4 have an Apple silicon native driver?
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Re: Crackling at low latencies on M1 Mac, recording audio with no plugins

Post by claz »

Indeed it does: https://motu.com/en-us/news/motu-and-macos-big-sur/

Some drivers require disabling the new hardened runtime, but I don't believe this one does.
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Re: Crackling at low latencies on M1 Mac, recording audio with no plugins

Post by claz »

It just occurred to me that this could be an electrical problem, and that the buffer size issue could be a red herring.

If it were electrical, I would expect constant noise of some kind, though, right, whether hum or crackle?

I do occasionally get a kind of quiet "nyeaahh" noise (pitched around 400Hz if memory serves) that seems to pass through the system -- it's less frequent, and I assume unrelated. I haven't had the DAW recording during that one, so I'm not sure if it's just in the monitors or the interface.

Electrical connections: Wall outlet --> power line conditioner (3 prong) --> keyboard, speakers, monitor, mac (all 3 prong, except keyboard, which is 2).

Not intentionally trying to complicate things, just trying to check all possibilities...
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Re: Crackling at low latencies on M1 Mac, recording audio with no plugins

Post by blinddrew »

Do you get the same issue with both speakers and headphones?
It might be worth starting with the simplest set up you can, i.e. Macbook on battery, M4, headphones, then adding components back in one at a time to see if something is triggering it - either a ground loop or a lack of a ground.
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Re: Crackling at low latencies on M1 Mac, recording audio with no plugins

Post by claz »

The battery idea is excellent, thanks -- the keyboard can even run on batteries, so I may start completely unplugged! (Though I still suspect it's buffer- or driver-related.)
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Re: Crackling at low latencies on M1 Mac, recording audio with no plugins

Post by Wonks »

If it goes away when you set the buffer size above 1024 samples, then I really don't think it's electrical noise related.

On a Windows machine, I'd suspect some other program hogging the processor, but I have no idea if this can happen with a Mac.

Got any hardware monitoring programs to view processor % usage when you get the crackles? If you aren't hitting 100% (or very near it) then it's not classic processor overload dropouts.
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Re: Crackling at low latencies on M1 Mac, recording audio with no plugins

Post by Sam Spoons »

OSX has an 'Activity Monitor' app built in which monitors the hardware in real time.
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Re: Crackling at low latencies on M1 Mac, recording audio with no plugins

Post by RichardT »

There’s no way an M1 machine should struggle with a load like that. If it goes away with higher buffer sizes, then it can’t be electrical, radio interference or ground related.

I don’t know much about the technology of digital audio, but does the fact that the crackles get recorded suggest there is a problem with what’s coming into the Mac - ie are the crackles being output by the A to D converter? I don’t know though, maybe incoming signals enter some kind of buffer on the Mac before being recorded, in which case the above is completely wrong.

In any event, something is wrong. Do you have another audio interface you could use to see if it works?
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Re: Crackling at low latencies on M1 Mac, recording audio with no plugins

Post by Dave Rowles »

Would totally agree. Have you got access to any other interface so you can test? I'd try changing the cable too because that's scuppered me a few times in the past.
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Re: Crackling at low latencies on M1 Mac, recording audio with no plugins

Post by Chromeman »

To the OP, if you go onto the Motunation website, you'll find quite a number of people with similar issues when using Apple Silicon Macs and MOTU hardware. No definitve solution but some have successfully changed cables, even replaced the unit itself etc etc. Maybe worth a read?
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Re: Crackling at low latencies on M1 Mac, recording audio with no plugins

Post by Bob Bickerton »

An M1 Mac would eat that - so the problem will be to do with the interface or connection cables.

Have you switched out all the cabling? How’s the keyboard attached? Via line input or USB? If line input what levels are you recording at? If you’re recording keys and vocals at the same time, is the crackling on all tracks or just some?

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