Apollo Hardware Manual
Front Panel
11
(10) Preamp Options LEDs
These seven LEDs display the state of the preamp option button settings for the currently selected channel.
Each LED is illuminated when its associated option is active. When the channel selection is changed, the LED
states are updated to reflect the current settings for the selected channel.
(11) Channel 1 – 4 Select LEDs
The currently selected channel is indicated by the LEDs above input level meters 1 – 4. When a channel (or
channels, when stereo linked) is selected, its associated LED is illuminated. The currently selected channel is
incremented when the Preamp Knob (#2) is pressed.
Note: The numbers for channels 5 – 8 do not illuminate.
(12) Input Level Meters
The 10-segment LED meters display the signal peak input levels for analog channels 1 – 8 at the input to the
A/D converters. The dB values of the input meter LEDs are indicated between the meters for channels 4 and 5.
When digital clipping occurs, the red “CLIP” LED illuminates. Avoid digital clipping at the channel’s A/D
converter by reducing the channel’s input level at its source, and/or in the case of channels 1 – 4, by reducing
the preamp gain or engaging the Pad (#7) and readjusting gain as needed.
(13) Power Indicator (UA Logo)
The Universal Audio logo illuminates when the external power supply is properly connected to the AC outlet and
the power input on the rear of the unit, and the Power switch (#22) is in the up position.
Clock LEDs
The Internal (“INT”) and External (“EXT”) Clock LEDs indicate the source and status of the system master clock.
The clock source is specified in the Interface panel of the Settings window within the Console application (page
20). For more information about clocking, see “Digital Clocking Basics” on page 27.
(14) Internal Clock
When Apollo is using its internal clock as the master clock source, the Internal Clock LED is solid green. When
set to external clock, this LED is not illuminated.
(15) External Clock
When Apollo is set to use an external clock as the master clock source and a valid clock signal is detected at
the specified port, the External Clock LED is solid green. Apollo can be configured to use an external clock from
the Word Clock, S/PDIF, or ADAT inputs. When set to internal clock, this LED is not illuminated.
If the External Clock LED is red and the Internal Clock LED is simultaneously green, Apollo is configured to use
an external clock but it cannot lock to the specified source, so the internal clock is active instead. In this
situation, if/when the specified external clock becomes available, Apollo will switch back to the external clock,
the Internal Clock LED will turn off, and the External Clock LED will change to green.
