Universal Audio Apollo - Manual (Page 20)

Apollo Hardware Manual Device Driver Setup 20
Sample Rate
This setting defines the sample rate that will be used by Apollo’s A/D and D/A converters and UAD Powered
Plug-Ins. Higher sample rates have increased frequency response and larger storage requirements than lower
rates (and with UAD Powered Plug-Ins, higher rates require more DSP).
Note that when Apollo is used with a DAW, the sample rate is set within the DAW application. In this scenario,
the sample rate setting in Console is updated automatically to match the DAW’s value (the value within
Console does not need to be configured manually to match the DAW setting).
Clock Source
Apollo’s master clock source for A/D and D/A conversion is set here. Internal clock or external clock from S/PDIF,
ADAT, or Word Clock input can be specified.
Only one device in a system can be the master clock. This setting must match the host DAW setting or audio
glitches could occur. For more information about clocking, see “Digital Clocking Basics” on page 27.
Line Outputs Reference Level
The reference level for line outputs 1 – 8 can be set to –10 dBV or +4 dBu in adjacent pairs with these drop
menus. The value is usually set to match the nominal input level of devices connected to these outputs (a
setting of +4 dBu outputs a higher signal level than –10 dBV).
Note: Reference levels for the line inputs are set in the Console application.
Monitor Output
The S/PDIF outputs can be configured to mirror the Monitor 1 & 2 outputs for connecting to the stereo inputs of
other devices with digital S/PDIF inputs such as a speaker system, stereo recorder, or external D/A converter.
S/PDIF Mirrors Monitor 1–2
The stereo S/PDIF output mirrors the output of Monitor 1 & 2 when this box is checked. When Mirror mode is
active, the Monitor Level knob will control the S/PDIF output level (the S/PDIF output is “post-fader” when
mirrored).
Note: When this box is checked, any DAW outputs (including Console aux outputs) that are routed to the S/PDIF
ports will not be heard, because the S/PDIF ports are switched to output the monitor bus instead.
DAW Settings
Digital audio workstation software contains settings to specify which audio interface will be used by the DAW
for audio I/O. When Apollo is selected within the DAW to be used as the audio interface, Apollo’s inputs and
outputs become available for routing within the DAW.
Each DAW has unique methods for controlling the audio interface I/O settings and routings; consult the DAW
documentation for specific instructions on how to setup a Core Audio (Mac) or ASIO (Windows) audio interface.
Audio Interface Buffer
The audio interface I/O buffer size is set within the DAW. This buffer size affects the amount of latency that will
be generated when using Apollo’s audio interface I/O and UAD Powered Plug-Ins loaded within the DAW
environment.
If the DAW’s software monitoring feature is used, this buffering latency may be unacceptable. However, by
using Console for monitoring (without using the DAW’s software monitoring feature), latency is a non-issue due
to Apollo’s Realtime UAD processing.
The audio interface buffer size also affects system performance. If the buffer setting is too low, glitches,
dropouts, and/or distortion could occur in the audio and overall responsiveness of the host computer may
become sluggish. If these symptoms occur when using Apollo, try increasing the buffer size.