Not getting any sound from the Monitor or Headphone outputs of your Apollo? Here's what to check first:
SOURCE Settings in Console
Monitor SOURCE Settings
First check your SOURCE settings in the Console application. The Monitor output source is set on the CONTROL ROOM strip which is accessed by clicking the CTRL ROOM button on the right hand side of the Console window.
Monitor source settings in the CONTROL ROOM strip
In most cases the Monitor Source should be set to MIX. This means that any audio routed to the MON L and MON R outputs (or outputs 1 and 2 in DAWs that don't use I/O labels) can be heard through the Monitor L/R outputs of the Apollo.
Headphone Source Settings
The Headphone (HP) output source is set on the CUE OUTPUTS popover, which can be accessed by clicking the CUE OUTPUTS button on the right hand side of the Console window, just below the CTRL ROOM button.
CUE OUTPUTS popover (Apollo Twin)
CUE OUTPUTS popover for Apollo Thunderbolt rack units
In most cases the Headphone (HP) source should be set to MIX. On Apollo Twin this is done by selecting the MIX button to the right of HP (shown in the picture above). On Apollo Thunderbolt rack units, this is done by setting the source of one of the Cues (typically CUE 1, as shown in the picture above) to MIX, and then selecting HP1 and/or HP2 to the right of that Cue.
Additional Console Settings
If the Monitor volume knob on your Apollo is blinking and you have no audio output, then you may have the DIM function enabled with the DIM AMOUNT set too high in the Console application. The settings for the DIM function are found on the CONTROL ROOM strip.
Settings for the DIM function in the CONTROL ROOM strip
If the DIM AMOUNT is set too high (such as -60 dB in the picture above) then having the DIM function enabled may effectively mute your Monitor outputs depending on your Monitor volume level and the volume of what you are listening to. When the DIM button is gray as shown above, the function is disabled - when the button is lit yellow the function is enabled.
If the volume knob on your Apollo is lit in up red then the Monitor output is muted in Console. To unmute, either press Apollo's volume knob in or click the MUTE button on the lower right side of the Console window (the button is gray when disabled and red when enabled).
Still having trouble? Check out the Apollo 16 & Apollo 16 mkII Basic Troubleshooting article.