iMac 17.1 audio glitch | MacRumors Forums

Hi everyone,

I have a peculiar problem with my iMac 5k Retina Late 2015. I’ve tolerated it for approx two years since I’ve never been able to locate the root of the problem.

Just a little background, I work with audio and music. I do post production audio in Pro Tools, music using Logic Pro X. Multichannel and spatial audio in Reaper and Supercollider. I use Universal Audio Twin MkII Quad as an interface.
I’ll post the full system report below but currently I’m running macOS Catalina 10.15.7 along with the latest software/ firmware for the audio interface.

Here is a video of the glitch happening.
(I was not able to figure out Quicktime Screen recording with internal audio so we’ll settle for an iphone video)

Since 2020-2021 I’ve experienced this glitches where the audio chops ~6x in sets of 2 for a short moment but then continues as normal. This happens irregularly, I feel as I’ve gone days without it happening but then some days it happens every few minutes.
Activity Monitor shows nothing out of the ordinary when it happens.
It affects the system as a whole, whether I’m streaming music, working in a DAW or watching a video online.
I have not experienced it while using Built in audio, so far I’ve only experienced it while using the UA Interface. However I’ve not used the Built in audio extensively to confirm that without doubt.

It does not affect the audio I work with, as in if I’m recording while it happens. But since I’ve started using Supercollider, which is a programming environment for audio synthesis, if I’m recording from SC into a DAW and it happens, SC will crap out and the audio processing is ruined.

Now, I’m aware of the discussion on here and elsewhere on the web regarding the iMac 17.1 and it’s failure to update the EFI. That is also the case with my computer, it’s stuck on However I’m not totally convinced my problem is related to that since I’ve yet to read anyone describe similar glitches. But who knows, certainly not me.

I recently updated to Catalina in hopes of it fixing the problem, I’ve been really reluctant with my OS upgrades. Summer of 2021 I went from High Sierra to Mojave. I feel like this has been present since Mojave, but I’m not certain if my memory is correct.

My experience with this iMac has been exceptional, I’ve never had any major problems (apart from this one) and it has been able to handle everything I throw at it so far. I’ve noticed a slight change in performance since going to Catalina but no deal breaker yet.

Does this sound familiar to anyone or does anyone have suggestions as to how to investigate further?

System Report:

Model Name: iMac
Model Identifier: iMac17,1
Processor Name: Quad-Core Intel Core i7
Processor Speed: 4 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 8 MB
Hyper-Threading Technology: Enabled
Memory: 32 GB
Boot ROM Version:
SMC Version (system): 2.33f12
Serial Number (system): DGKT7HF8GQ18
Hardware UUID: 25AF35B0-4980-52B8-ABD2-1E90A2E3DA12

Physical Drive:
Device Name: APPLE SSD SM0256G
Media Name: AppleAPFSMedia
Medium Type: SSD
Protocol: PCI
Internal: Yes
Partition Map Type: Unknown
SMART Status: Verified

iMac 17.1 audio glitch | MacRumors Forums

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