Qu – USB channel I/O clarification

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This topic contains 3 replies, has 3 voices, and was last updated by Profile photo of KeithJ A&H KeithJ A&H 1 year, 8 months ago.

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  • #107422
    Profile photo of blaggers

    New Qu24 user here.

    Im trying to clarify in my mind how the USB channel I/Os work and the manual isnt very clear.

    From trial and error I think the following is how it works – can any one confirm/clarify?

    QU24 has 32 USB Out Channels = can be mapped to Ch 1 – 24 , 3x stereo pairs , Mixes, etc = Set via “Setup -> I/O Patch Setup –> USB Audio” screen

    QU24 has 30 USB Input Channels = Mapped one to one (ie USB01 = Channel 01, USB02 = Channel 02)
    USB channel sends from external devices need to be set on the sending device.
    So the “Setup -> I/O Patch Setup –> USB Audio” has no effect on incoming USB audio mapping (even though its in the I/O section)?

    The particular issue I had was sending USB audio from an iPad, where I could only get it to appear on Channels 1 and 2 despite what I set in USB Audio screen. A windows PC allows USB audio to appear on ST1, ST2 or ST3 (set on the PC sound settings window) – is there any way to set IOS devices to use the same ST3 mapped USB Audio channel I usually have the PC on?


    Profile photo of Giga

    What happens if you switch ST3 to usb-b input before you connect the iPad ?


    Profile photo of blaggers

    Hi Giga,
    Thanks for the response. ST3 is permanently set to USB-B (as it used for my PC audio channel) – when I swapped the USB cable to the iPad all audio stopped until I changed Channel 1 and channel 2 to USB-B inputs.

    Profile photo of KeithJ A&H
    KeithJ A&H


    To confirm what you’ve already mentioned here, you can patch your any outputs from the Qu to any of the USB output channels.
    Then on the way back into the Qu everything is patched 1-to-1, so when using a DAW with the Qu as your USB interface, you could patch to Qu channel 9 and it would appear as the USB-B input on channel 9.
    The stereo options for WDM are a special case of mapping/patching using the Windows driver – on macOS and iOS the Qu is class compliant so with multichannel apps it will be seen as a multichannel device, but with stereo apps, you may only see two channels. With macOS you can use your system setup to decide which channels are used, but with iOS, it will often use just the first two it sees (1&2 as you found).

    So no, I’m afraid there is no way to have a stereo digital output from the iPad via USB-B appear at the ST3 channel, we would generally recommend using the ST3 3.5mm Jack socket for this though, as it leaves the USB-B free to connect to a computer.


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