Apple has a serious, unresolved bug that causes issues with audio performance with external interfaces across all its latest Macs, thanks to the company’s own software and custom security chip.

Following bug reports online, the impacted machines are all the newest computers – those with Apple’s own T2 security chip:

iMac Pro

Mac mini models introduced in 2018

MacBook Air models introduced in 2018

MacBook Pro models introduced in 2018

Impacted hardware of this and possibly other bugs includes most external USB 2.0 audio hardware. We have have some reports of issues over FireWire, which initially had seemed like a refuge. Perversely, readers are also reporting widespread issues with Apple’s own internal audio (speakers and headphone jack).

The T2 in Apple’s words “is Apple’s second-generation, custom silicon for Mac. By redesigning and integrating several controllers found in other Mac computers—such as the System Management Controller, image signal processor, audio controller, and SSD controller—the T2 chip delivers new capabilities to your Mac.”

The problem is, it appears that this new chip has introduced glitches on a wide variety of external audio hardware from across the pro audio industry, thanks to a bug in Apple’s software. Issues with the way the new chip synchronizes timing causes dropouts and glitches in the audio stream. (It seems basically all USB 2.0 audio interfaces will be impacted. This of course unfortunately leads users to blame their interface manufacturer, but the fault lies with Apple.)

Switching off “Set date and time automatically” in System Preferences will reduce, but not resolve the issue. Nebulae aka Abid Hussain, an Ableton Certified trainer, writes in comments:

Unchecking the time sync only reduces the dropouts. You need to also uncheck the location sync in the Time Zone tab, but even then you’re only reducing the dropouts. Any time the T2 chip tries to sync, it will overload the USB2.0 bus, causing dropouts. There is no way any musician should go on stage with a 2018 [Mac] and a USB2.0 audio interface directly connected to it. The only solutions are 1) Get a Thunderbolt or USB3.0 audio interface, or 2) Use a Certified Thunderbolt 3 powered hub (not a bus-powered or cheap non-certified hub) – Cable Matters has a solution for $169 on Amazon, but most of those hubs are at least $200-300. Using a certified TB3 hub creates a separate external USB2.0 bus, in which you can run your USB2.0 audio interface. The cheap hubs do not work because they don’t run on the TB3 bus, and therefore they don’t create their own separate USB2.0 bus, which means you’re going to get dropouts.

To clarify: all T2-based Macs, that is all Mac models from the 2018 generation, are evidently unusable with USB 2.0 audio interfaces, irrespective of vendor. Audio interfaces using FireWire or Thunderbolt are reportedly unaffected by this particular bug, but USB 2.0 is for the moment the most popular bus for audio devices, so nearly all owners of the new machines are encountering the issue. (There are also some reports that USB3 devices are unaffected, but I can’t confirm that and those devices are rare. Note that even some audio interfaces with USB-C connectors do actually make use of the USB2.0 bus.)

This of course has led some users to simply buy a new Thunderbolt 3 audio interface. But this situation is unacceptable – plenty of standard, inexpensive PCs have no such issues with Thunderbolt and USB audio hardware. Apple has shipped their entire computer line with buggy firmware that renders those machines unusable for the majority of people working with sound (so music, video, and audio production), and have lagged in finding a solution for months after shipping these expensive machines. Not only that, but is anyone clear on what problem the T2 security chip even solves? Apple now loves crowing about its “custom silicon” often without even explaining to us why anyone needs it.

Anyway, for now that’s the set of choices, until Apple ships a comprehensive, tested fix:

1. Mac users on older machines should postpone upgrading.

2. Mac users in the market purchasing a new machine right now should consider a comparable Windows machine.

3. Users stuck with these models should use a Thunderbolt 3 audio interface, adapter, or hub, or attempt to return the computer in favor of an older Mac or new PC.

More:

https://www.reddit.com/r/apple/comments/anvufc/psa_2018_macs_with_t2_chip_unusable_with_external/

https://discussions.apple.com/thread/8509051

https://www.logicprohelp.com/forum/viewtopic.php?t=138992

https://www.gearslutz.com/board/music-computers/1232030-usb-audio-glitches-macbook-pro-2018-a.html

https://openradar.appspot.com/46918065

This represents another serious quality control fumble from Apple. The value proposition with Apple always been that the company’s control over its own hardware, software, and industrial engineering meant a more predictable product. But when Apple botches the quality of its own products and doesn’t test and resolve creative audio and video use cases, that value case quickly flips. You’re sacrificing choice and paying a higher price for a product that’s actually worse.

Apple’s recent Mac line have also come under fire for charging a premium price while sacrificing things users want (like NVIDIA graphics cards, affordable internal storage, or extra ports). And on the new thin MacBook and MacBook Pro lines, keyboard reliability issues.

Some of those mainstream PC vendors do now test with third-party pro audio hardware (I’ve talked to Razer about this, for instance). And that’s to say nothing of vendors like pcaudiolabs who custom-configure each machine for the actual DAWs. Apple clearly has the resources to do the same, and they make a DAW of their own (Logic Pro). This appears to be an issue they could possibly have reproduced and corrected before shipping.

Updated: The 2018 iPad Pro also suffered from audio issues, which appear to be software related. This seems not to have any direct relation to the issue with the Mac line, but is further evidence of some quality control and testing issues involving real-time audio performance and Apple firmware and software.

If you do have one of these machines, let us know if you’ve been having trouble with this issue and if this workaround (hopefully) solves your problem.