Audio Pro Rack-mountable 8 x 8 USB 2.0 Interface with MX Core DSP Technology 8R - Manual (Page 15)

User Guide 14 Fast Track Ultra 8R
Sync Source
This drop down menu lets you select the clock source of Fast Track Ultra 8R. To synchronize the interface to an external
digital source (i.e., the incoming S/PDIF signal), select the “External” setting. To synchronize Fast Track Ultra 8R to its own
internal clock, select “Internal.” Please see the box below for more information about the digital input and external clocking.
About External Clock
Digital audio is based on samples. For example, a digital recording at a sample rate of 44.1 kHz contains 44,100
samples, or digital “snapshots,” per second. Each digital audio device has its own internal clock, or crystal, to generate
and control the exact rate and timing of these samples during every second. In order for two or more digital audio devices
to function together, only one of their clocks can be in control (the Master), while any other devices must be synchronized
to that device’s clock (the Slave). Otherwise, the resulting audio will sound distorted, play at the wrong speed, or have
clicks and pops.
You can set Fast Track Ultra 8R to run as the Word Clock Master (“Internal”) when digitally connected to other digital
audio devices:
Connect the S/PDIF output of Fast Track Ultra 8R to the S/PDIF input of another digital audio device and configure
that device to synchronize to its S/PDIF input (making it the word clock Slave).
Alternatively, you can set another device to act as the Word Clock Master and designate Fast Track Ultra 8R to run as the
word clock slave:
Connect the S/PDIF output of a 3rd party audio device to the S/PDIF input of Fast Track Ultra 8R. Select ”External”
as the clock source setting from within the Fast Track Ultra 8R Control Panel. Fast Track Ultra 8R now runs in sync
to the digital S/PDIF signal generated by the other device.
Note that Fast Track Ultra 8R can only receive input signal from its S/PDIF input when the clock setting has been set
to “External.” In this configuration, Input channels 7 and 8 receive their signal from the S/PDIF input instead of from
Mic/Line Inputs 7/8.
Driver Settings
ASIO/WDM Buffer Size (Windows only)
Latency is defined as the time it takes for your input signal to pass through your audio software and appear at
the outputs. This latency can result in a delay that is undesirable when overdubbing to existing tracks.
This drop-down menu lets you select the size of the buffer in samples. Smaller buffer sizes result in lower
latency, but may not function well with slower systems, causing clicks, pops and dropouts in the audio
playback.
The default buffer size is 256 samples. If you are experiencing clicks and pops in your audio, try increasing the
buffer size.
ASIO Direct Monitoring (Windows only)
Many Windows applications that support ASIO 2.0, also support ASIO direct monitoring. ASIO Direct
Monitoring allows your ASIO-compatible software to remotely access and control some routing and monitoring
functions of the Fast Track Ultra 8R Control Panel. If you prefer to not use ASIO Direct Monitoring, uncheck
the box marked “ASIO Direct Monitoring” on this tab. Please refer to your DAW application’s user guide for
more information on implementing ASIO direct monitoring.
High Performance Mode (Windows only)
Clicking this box engages High Performance Mode, which further reduces software monitoring latency and
also reduces the load placed on your CPU. Most computers support High Performance Mode, however, if you
experience any unexpected results (e.g., system instability, unresponsiveness, etc.), disable High Performance
Mode. By default, this box is left unchecked.