For an Apple computer there are some options that allow you to record with the Ayre A/D
converter. For more information on software choices, please refer to the Recording section
after completing the following setup process.
There are a few minimum requirements that must be met to achieve reliable recordings to
your system from the Ayre A/D Converter. These requirements are as follows:
- Apple OS X 10.4.x or newer.
- A dedicated USB port with an unshared USB Controller. To learn more on how to find
out if your USB port is shared, please follow the setup instructions below.
Setting up your Mac to get the best sound is quite simple. Here are the steps:
1. Apply power to your Ayre A/D converter. After applying power, connect the USB cable from
the A/D converter to your computer USB port.
On the Dock select the “Finder” app.
Select “Places - Applications”, scroll down the list and click on the “Utilities” folder.
Find the “Audio MIDI Setup.app”.
2. Open the “Audio Midi Setup” application and select “Audio Devices”.
In the properties section, select the Ayre USB A/D converter and choose the maximum sample
rate in the “Audio Output” section. Normally this will be “192000.0 Hz”. Most recording
software will allow you to record at sample rates below this maximum setting, so by setting
it to the maximum value here, we prevent the OS from limiting the maximum sample rate.
The Ayre A/D converter will automatically operate in Class Two mode when connected to an
available USB 2.0 port on your system. Due to the much higher data transmission rate, it is
very important to ensure that the USB cable used and port that the A/D converter is
connected to will allow reliable communications. Please see the section on USB Cable
Requirements in the general Analog to Digital section if you have not already. To determine
whether your USB port is shared or unshared, follow the steps below.
Determining Whether a USB Port is Shared or Unshared
While old or poorly designed USB controller chips can cause problems with Class Two Audio,
please remember that the latest version of Snow Leopard is required to reach speeds of 192
kHz. Since Snow Leopard only runs on Intel-based Apple computers, these are all fairly new
machines and generally you should not run into any problems in this regard.
However, there is one cardinal rule—for Class Two Audio the Ayre USB A/D converter
cannot share a USB controller with any other devices.
To ensure that the Ayre USB A/D converter is running on its own dedicated USB controller is
largely a matter of trial-and-error. Normally the physical USB port will be connected to a
"smart" controller that automatically changes from USB 1.1 (Full Speed) to USB 2.0 (High
Speed or "Enhanced), depending on the requirements of the attached peripheral device.
However, there will not be a dedicated controller for each port, so sometimes it may be a
bit of a trick to find an arrangement whereby the Ayre USB A/D converter has its own
dedicated USB controller.
Many Apple computers will already have internal devices (laptop cameras, IR receivers,
Bluetooth external devices (mouse, keyboard, iPod dock, hard drive, et cetera) connected.
The more devices connected, the more difficult it becomes to ensure that the Ayre USB A/D
converter has dedicated access to a High Speed USB controller. Sometimes it will be helpful
to disable any unused USB devices to allow more flexible configuration of the necessary
To determine which USB devices are connected to which controllers, go to "Apps - Utilities
- System Profiler".
On the left side click on "Hardware - USB". On the right side will be a section labeled
"USB Device Tree". With the Ayre USB D/A converter plugged into the computer (the green USB
indicator light is on), the goal is to have the USB device labeled "Ayre USB Interface" as
the sole device under a controller labeled "USB High-Speed Bus".
To achieve this you may need to try connecting various combinations of USB devices into
the USB ports. Each time you change the connection, you will need to select "View -
Refresh" from the Menu Bar at the top of the screen.
Should you run out of available
USB ports, you may need to purchase a USB port expander (hub). Often these are built into
peripheral devices such as keyboards or displays. When using a USB hub, only connect slower
Full Speed (USB 1.1) devices through the hub whenever possible.
Do not connect your Ayre USB A/D converter to your computer through a hub, as this may
cause dropouts, clicks, or other disruptions. Do not share the controller labeled "USB
High-Speed Bus" in the System Profiler with other High Speed devices (external hard disk
drives, iPod connectors or docks, et cetera).
Should your Ayre USB A/D converter stop responding, go to "Apps - System - Sound". If the
"Ayre USB Interface" is not listed under Input, try "re-booting" the A/D converter by
unplugging the USB cable for ten seconds and then reconnecting it. This is a semi-common
experience when using an iPod, which is a High Speed device. Unless it has been determined
that the iPod connector (or dock) is on a separate USB controller during the setup process,
connecting the iPod will "kick off" the Ayre USB A/D converter from the "USB High-Speed
Bus". While "re-booting" the Ayre A/D converter will solve the problem temporarily, you
will need to reconfigure the USB connections to your computer to avoid future problems.
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