User Manual
Apollo 8 Hardware Manual Front Panel 13
Preamp State Indicator
In addition to the channel’s relative preamp gain, the ring also indicates the current state 
of the preamp channel:
Green (variable) – The preamp is in default operating mode with variable gain
Green (fixed at maximum) – LINE is selected for the channel (#4) and LINE INPUT GAIN 
is set to BYPASS in the Hardware panel within the Console Settings window
Unlit – The preamp gain is set to its minimum value
Orange – A Unison plug-in is active in Console’s dedicated Unison insert for the channel.
Note: See the Unison chapter within the Apollo Software Manual for complete 
details about Unison operation.
(4–9) Preamp Options
This set of six switches control the preamp options for input channels 1 – 4. Press the 
switches to toggle the setting. The current state of each preamp option is indicated by 
the LED within each switch. Each switch function is detailed below.
(4) Mic/Line
This switch switches between the channel’s Mic (XLR) and Line (¼”) inputs on the rear 
panel combo jacks. This switch has no effect if the channel’s Hi–Z input is connected 
(the Hi-Z input must be disconnected to use the Mic/Line inputs).
Note: Line inputs 1 – 4 can be set to bypass the preamp circuitry. See Line Input 
Gain Bypass for additional details. 
(5) Low Cut Filter
When enabled, the channel’s input signal passes through a low cut (high pass) filter. This 
2nd-order coincident-pole filter has a cutoff frequency of 75 Hz with a slope of 12 dB 
per octave.
The Low Cut filter affects the Mic, Line, and Hi-Z inputs. Low Cut is typically used to 
eliminate rumble and other unwanted low frequencies from the input signal. 
(6) Phantom Power (+48V)
When enabled, 48 volts of phantom power is supplied at the channel’s rear panel XLR 
input. Most modern condenser microphones require 48V phantom power to operate. This 
option can only be activated when the Mic/Line switch (#4) is set to Mic.
Caution: To avoid potential equipment damage, disable +48V phantom power on 
the channel before connecting or disconnecting its XLR input.
Depending on the current configuration of the hardware and software, there may be a 
delay when changing the +48V state to minimize the clicks/pops that are inherent when 
engaging phantom power. The +48V LED will blink rapidly during any delay.










