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Logic 9 Problem With Aggregate Devices

Discussion in 'Logic 9' started by Matthew Jones, Sep 2, 2016.

  1. Matthew Jones

    Matthew Jones New Member


    I have been using an aggregate output in Logic that's been working fine but have run into a problem recently when I removed one of my 3 aggregated devices and changed it for a firewire output device (Behringer FCA 202) and found there to be a loud ringing noise (perhaps like a USB ground loop ring) coming out of the Behringer's ouput. The Behringer & my other interfaces do not have this issue when used outside an aggregate setup and so I think I can narrow the problem to within Logic, but I have experimented with everything I can think of within Logic & the Audio MIDI Setup. I have previously had the same issue when I aggregated my Macbook's headphone output with other interfaces, so I simply took it off but I can't understand why it might do this with the Behringer. The other devices are a Focusrite Saffire 6 USB and a Mackie VLZ USB mixer. The Behringer replaced a Roland TB-3 because the TB-3 only works at 96kHz whereas the others can all do 44.1kHz.

    The problem is only happening when the aggregate output is combined of USB outputs and non-USB outputs (ie FireWire or laptop headphone) so I am wondering what it is about combining USB and non-USB outs that causes this noisy squeel. When I selected aggregate output in my System Preferences as a general Mac audio output the same noise did not occur so everything seems to suggest it is Logic that has an issue.

    Any advice would really be much appreciated.
    Last edited: Sep 2, 2016
  3. bambony

    bambony Administrator Staff Member

    Can you try another DAW to see if the ringing still occurs? For example Reaper is free to trial..

  4. Matthew Jones

    Matthew Jones New Member

    Yes I've found it does occur outside using Logic and can conclude that Logic is not creating the problem. In fact the Behringer device doesn't even need to be part of the aggragated output to get the noise. It seems to get the noise when any other USB audio device is also in use. It is fine being used completely on its own, but noisy as an aggragated set or if any other USB audio output is in use.

    In the past I have found similar noise when USB devices have been under-powered with an unpowered hub, although all my current ones are either AC powered or connected to a powered hub.

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