Universal Audio Apollo - Manual (Page 10)

Apollo Hardware Manual Front Panel 10
Each time the knob is pushed, the selected preamp channel is incremented. If stereo linking is active, the
stereo pairs are selected.
(3) Preamp Gain Level Indicator
The amount of preamp gain for the selected channel is displayed with the ring of illuminated green indicator
LEDs surrounding the Preamp Knob.
The LEDs are relative levels and are not calibrated to indicate any specific dB value. However, precise
numerical dB gain values for the preamps are displayed in the Console application.
(4–9) Preamp Settings
This set of six buttons control the preamp options for input channels 1 – 4. Press the buttons to toggle the
setting. The current state of each preamp option button is indicated by the Preamp Options LEDs (#10 on page
11). Each button function is detailed below.
(4) Mic/Line
This button switches between the channel’s Mic and Line inputs on the rear panel. This button has no effect if
the channel’s Hi–Z input is connected (when a cable is inserted into the Hi-Z input, the Mic/Line LED turns off).
(5) Low Cut Filter ( )
When enabled, the channel’s input signal passes through a low cut (high pass) filter. This 2 nd -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 to the channel’s rear panel Mic 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.
Note: 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.
(7) Pad
When enabled, the channel’s microphone input signal level is attenuated by 20 dB. Pad does not affect the Line
or Hi-Z inputs.
Pad is used to reduce signal levels when overload distortion is present at low preamp gain levels, such as when
particularly sensitive microphones are used on loud instruments, and/or if the A/D converter is clipping.
(8) Polarity (ø)
When enabled, the polarity (aka “phase“) of the input channel’s signal is inverted. Polarity affects the Mic,
Line, and Hi-Z inputs.
Polarity inversion can help reduce phase cancellations when more than one microphone is used to record a
single source.
(9) Stereo Link
This button links the preamp controls of adjacent channels together (1 & 2 or 3 & 4) to create stereo input
pairs. When channels are linked as a stereo pair, any preamp control adjustments will affect both channels of
the stereo signal identically.
Only the same type of inputs can be linked (Mic/Mic or Line/Line), and the Hi-Z inputs cannot be linked.