I’m trying to determine whether this is a CQ-18T issue, a macOS issue, or a compatibility problem between the two.
Setup:
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Allen & Heath CQ-18T
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Firmware: 1.2.2 r4248 (latest)
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MacBook Pro M4 Max
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macOS Tahoe 26.5
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Direct USB connection (no hub or dock)
Problem:
When audio is playing through the CQ-18T (YouTube, Apple Music, etc.) and I switch the audio output from the CQ-18T to MacBook Pro Speakers, the CQ-18T starts producing a continuous beep from its outputs.
What’s strange is:
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If I pause or stop the music before switching outputs, there is no issue.
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If I switch outputs while audio is actively playing, the beep starts.
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If I close Chrome while YouTube is playing, the beep can continue even after Chrome is closed.
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The beep only comes from the CQ-18T outputs, not from the MacBook speakers.
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Unplugging and reconnecting the USB cable immediately stops the beep.
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Restarting Core Audio (
sudo killall coreaudiod) does not stop the beep.
Things I’ve already tried:
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Latest CQ-18T firmware
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Direct USB connection
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Brand new macOS user account
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Matching sample rates (96 kHz)
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No BlackHole, Aggregate Devices, or Loopback installed
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Same issue across different apps
Interesting observation:
I tested the same CQ-18T on another MacBook Pro running the same macOS Tahoe 26.5, and the problem does not occur there.
Has anyone seen a CQ-18T or USB audio interface get stuck in a beeping state after an output device switch on macOS? Any ideas on additional troubleshooting steps?