How to Check the Conflict Between Logic Pro & External Devices
- 1). Install any software drivers corresponding to your external device, if you have not done so already. Many interfaces, mixers and USB adapters include an installation CD containing the necessary drivers needed for your hardware to communicate with your computer. Insert the CD into your computer's CD-ROM drive and double-click the installer on your desktop.
- 2). Open your Logic preferences, Click the "Logic Pro" menu in the upper, left corner of your screen, hover your mouse over the "Preferences" heading and select "Audio."
- 3). Click the "Devices" tab near the top of the "Preferences" window and select the "Core Audio" tab that appears just below.
- 4). Click the menu appearing beside the word "Device" and select your external device from the list of options. Make sure that the "Recording Delay" slider reads "0" and that the "Universal Track Mode" and "Software Monitoring" boxes are both checked. Click the "Apply Changes" button to save your modifications.
- 5). Check your MIDI settings if connecting a digital instrument with a MIDI cable. Click the "MIDI" tab along the top of your "Preferences" window. Your MIDI signals should transmit through Logic without any specific settings changes, but if you cannot achieve any sound from your MIDI controller, click the button that reads "Reset All MIDI Drivers" and try again.
- 6). Click your "Arrange" window, which appears as your main project window. If your "Arrange" window does not appear on your screen, click "Window" on your menu bar and select "Arrange" from the drop-down list.
- 7). Select a track on your screen that corresponds to your type of external device. Your tracks are your horizontal recording layers, appearing from the top to the bottom of your window. If you try to play a MIDI keyboard on an audio (analogue) track, you will not hear any sound. Likewise, if you try to transmit sound from a mixer or interface to a MIDI (digital) track, you will not hear sound. Your analogue tracks appear on your "Arrange" window (in the left column) with the word "AUDIO," while your digital MIDI tracks appear with the word "INST." Select the correct track type before you begin using your external hardware.
Source...