Recent iMacs (2019, 2020) + audio interface performance over Thunderbolt?

[mvsr]

I've got a 2019 iMac (i9, 72GB RAM, 1TB SSD) and my two Thunderbolt 3 interfaces (Quantum 2626 and Apollo Twin X TB) are not very stable in Studio One 5 or Ableton @ 44.1/64 samples. If I set up a simple drum loop, no CPU taxing plugins or anything, I'll start getting "Audio IO Overload" messages every so often - more regularly with the Apollo Twin X.

At 128 samples, the issue seems to disappear (at the cost of higher latency, of course), or I just haven't left Console running long enough to catch one.

With a USB 3 interface (MOTU M4), 64 samples does not cause the IO Overload error.

I'm wondering if there's anything I can do, if this is just the expectation with current Macs (T2 chip?) and Thunderbolt, or if it might be my iMac.

 

[kkclstuff]

what happens at a basic rate 48/24bit or 96/24 or 32?

 

[mvsr]

what happens at a basic rate 48/24bit or 96/24 or 32?

The overloads scale - 44.1/64 samples and 96/128 samples have about the same number of overload errors, 44.1/128 and 96/256 both seem to be pretty clear of the overloads.

 

[rkuo]

I've got a 2019 iMac (i9, 72GB RAM, 1TB SSD) and my two Thunderbolt 3 interfaces (Quantum 2626 and Apollo Twin X TB) are not very stable in Studio One 5 or Ableton @ 44.1/64 samples. If I set up a simple drum loop, no CPU taxing plugins or anything, I'll start getting "Audio IO Overload" messages every so often - more regularly with the Apollo Twin X.

At 128 samples, the issue seems to disappear (at the cost of higher latency, of course), or I just haven't left Console running long enough to catch one.

With a USB 3 interface (MOTU M4), 64 samples does not cause the IO Overload error.

I'm wondering if there's anything I can do, if this is just the expectation with current Macs (T2 chip?) and Thunderbolt, or if it might be my iMac.

Anything else sharing bandwidth on those thunderbolt interfaces?

 

[mvsr]

Anything else sharing bandwidth on those thunderbolt interfaces?

Nothing, just cable from iMac to interface, no daisy chaining.

 

[mvsr]

Finally remembered to copy the entire error.

HALC_ProxyIOContext::IOWorkLoop: skipping cycle due to overload
Audio IO Overload inputs: 'QT4H257' outputs: 'QT4H257' cause: 'Unknown' prewarming: no recovering: no

 

[rkuo]

Sounds like this issue: https://arstechnica.com/civis/viewtopic.php?f=19&t=1450519

Apple being Pro only in the marketing sense.

 

[mvsr]

Sounds like this issue: https://arstechnica.com/civis/viewtopic.php?f=19&t=1450519

Apple being Pro only in the marketing sense.

That's the confusing part - I can find many USB-related sound issues, and T2-related sound issues... but this iMac is having the issues over Thunderbolt and doesn't have the T2 chip.

I've got a new iMac on order to relegate this one for at-work duty, guess I'll stress test it when it arrives and if there's no improvement it's time to finally look at Windows.