Apollo Hardware Manual
Front Panel
12
(16) UAD Link LED
The UAD Link LED is a system status indicator. The LED is solid green when Apollo is connected to (and properly
communicating with) the host computer system via FireWire or Thunderbolt, and off when not connected. When
blinking red/green, the UAD drivers are not properly loaded. When solid red, the LED indicates an error state.
The Apollo software must be properly installed and configured on the host computer to enable the UAD Link,
and the UAD Link must be active to use Apollo with any/all computer operations. The only time the link is not
required is when Apollo is used “standalone” without a computer (see “Standalone Use” on page 7).
(17) Monitor Output Level Meters
The 10-segment LED meters display the signal peak output levels for monitor outputs 1 & 2 (Left & Right) at
the output of the D/A converters. These meters are before the Monitor Level control (“pre-fader”) and reflect the
D/A converter levels regardless of the current Monitor Level and Headphone Level knob settings.
The dB values of the monitor meter LEDs are indicated between the left and right channel meters. When digital
clipping occurs, the red “CLIP” LED illuminates. Avoid clipping at the monitor D/A converters by reducing the
monitor bus output level and/or the channels feeding the monitor output bus.
(18) Monitor Level and Mute Knob
This “endless” rotary encoder serves two functions. Rotating the knob adjusts the monitor output level, and
pushing the knob mutes the monitor outputs.
Monitor Level
Rotating the knob clockwise increases the signal level at monitor outputs 1 & 2 on the rear panel. Although this
is a digital control, the monitor volume is attenuated in the analog domain, after D/A conversion (digitally-
controlled analog volume). This method provides the utmost monitoring fidelity, in contrast to digital volume
controls that reduce levels by truncating the word length (“dropping bits”).
Monitor Mute
Pushing the Monitor knob toggles the mute state of the signals at monitor outputs 1 & 2 on the rear panel.
When the monitor outs are muted, the Monitor Level Indicator (#19) is red.
Note: Monitor Mute does not mute the headphone outputs.
(19) Monitor Level Indicator
The signal level at the rear panel monitor outputs is displayed with this ring of illuminated indicator LEDs
surrounding the Monitor Level knob. The LEDs are green when the monitor outputs are active, and red when the
monitor outputs are muted. This meter is after the Monitor Level control (“post fader”). It indicates relative
levels only and is not calibrated to specific dB values.
(20) Headphone Level Knobs 1 & 2
These analog knobs control the volume of Headphone Outputs 1 & 2 on the front panel. Each headphone output
has its own volume control. Headphone levels are attenuated in the analog domain (after D/A conversion) for
maximum fidelity.
(21) Headphone Outputs 1 & 2
These ¼” stereo TRS phone jacks are for connecting stereo headphones to Apollo. Headphone outputs 1 & 2 are
individually addressable by the device drivers and the Console application. Unique mixes can be created for
each headphone output, or they can be switched to mirror the monitor outputs in the Console application or
Console Recall plug-in. When mirroring the monitor outputs, the headphone outputs are unaffected by Monitor
Mute (#18), to facilitate recording/tracking with headphones while the monitor speakers are muted.
(22) Power Switch
This switch applies power to Apollo. When the unit is powered on, the Universal Audio logo is illuminated. The
external power supply must be properly connected for this switch to function.
