Mac os x faq – RME Fireface UCX II 40-Channel USB-B Audio/MIDI Interface User Manual

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User's Guide Fireface UCX II

15. Mac OS X FAQ

15.1 MIDI doesn't work

In some cases the applications do not show the MIDI port. The reason for this is usually visible
within the

Audio MIDI Setup

. It displays no RME MIDI device, or the device is greyed out and

therefore inactive. Mostly, removing the greyed out device and searching for MIDI devices again
will solve the problem.

The Fireface

’ MIDI is class compliant. Therefore it comes without a driver. OS X recognizes it as

MIDI device and will be using it with the driver included in the operating system.

15.2 Repairing Disk Permissions

Repairing permission can solve problems with the installation process - plus many others. To do
this, launch

Disk Utility

located in

Utilities

. Select your system drive in the drive/volume list to

the left. The

First Aid

tab to the right now allows you to check and repair disk permissions.

15.3 Supported Sample Rates

RME's Mac OS X driver supports all sampling frequencies provided by the hardware. This in-
cludes

32 kHz

and

64 kHz

, and even

128 kHz, 176.4 kHz

and

192 kHz

But not any software will support all the hardware's sample rates. The hardware's capabilities
can easily be verified in the

Audio MIDI Setup

. Select

Audio devices

under

Properties of:

and

choose the Fireface. A click on

Format

will list the supported sample frequencies.

15.4 Channel Count under Core Audio

At a sample rate of 88.2 or 96 kHz, the ADAT optical input and outputs operate in S/MUX mode,
so the number of available channels per port is reduced from 8 to 4. At a sample rate of 176.4
and 192 kHz, the ADAT optical input and output operates in S/MUX4 mode, so the number of
available channels is limited to 2.

It is not possible to change the number of Core Audio channels without a reboot of the comput-
er. Therefore whenever the Fireface changes into Double Speed (88.2/96 kHz) or Quad Speed
mode (176.4/192 kHz) all channels stay present, but become partly inactive.

Single Speed

Double Speed

Quad Speed

Fireface Analog 1 to 8

Fireface SPDIF

Fireface AES

Fireface ADAT 1 to 8

Fireface ADAT 1 to 4

Fireface ADAT 1 to 2