Hardware manual

Apollo FireWire Hardware Manual Front Panel

Front Panel

This section describes the features and functionality of all controls and visual elements on the Apollo front

panel. Note that all front panel functions, except the headphone volume knobs and power switch, can be

controlled remotely with the included Console software application.

(1) Hi-Z Inputs 1 & 2

The Hi-Z (high impedance) JFET direct inputs are for connecting low-level passive devices such as electric

guitar and bass instruments into channels 1 & 2 for A/D conversion. Connect only ¼” unbalanced TS phone

plugs to these inputs; TRS plugs cannot be used.

The Hi-Z inputs have an ultra-high input impedance of 2.2 Megohms that eliminates impedance loading,

preserving the high-frequency content of signals from sources with high impedance outputs (such as electric

guitar pickups). Hi-Z input gain levels are adjusted with the Preamp control for the associated channel.

Automatic Input Detection

Hi-Z inputs 1 & 2 use the same A/D converter channels as the corresponding Mic 1 & 2 and Line 1 & 2 inputs.

When a device is plugged into a Hi-Z input, the Mic and Line inputs for the channel are overridden, the Mic/Line

switch for the channel has no effect, and the stereo link is severed (if active). To use Mic or Line inputs 1 or 2,

its corresponding Hi-Z input must be disconnected.

(2) Preamp Gain & Channel Select Knob

This rotary encoder with integrated pushbutton serves two functions. Rotating the knob adjusts the preamp

gain for the selected input channel, and pushing the knob selects which preamp channel (1 – 4) is affected by

the front panel preamp controls.

Preamp Gain

The preamp gain of analog inputs 1 – 4 is adjusted with this control. The channel to be adjusted (1 – 4) is set

with the Channel Select function. The input to be adjusted (Mic, Line, or Hi-Z) is determined by the state of the

channel’s Mic/Line switch or Hi-Z input (if connected).

Rotating the knob clockwise increases the preamp gain for the selected channel. The available gain range for

preamp channels 1 – 4 is 10 dB to 65 dB for the Mic, Line, and Hi-Z inputs.

Note that it takes more than a full revolution of the Preamp Gain Knob to move through the available range.

This increases the control resolution for more precise preamp gain adjustments.

Only analog inputs 1 – 4 have input gain adjustment via the mic preamp controls. To adjust signal levels for

inputs 5 – 18, use the output level controls of the devices that are connected to those inputs.