Presonus Audio electronic FIREBOX user manual Controls and Connections

3 CONTROLS AND CONNECTIONS

NOTE: Active instruments are those that have an internal preamp or a line level output. Active instruments should be plugged into a line input (3 or 4) rather than into an instrument input. In other words, don’t plug an active instrument into the combo jacks on channels 1 or 2.

3.Input Gain/Trim Control. This knob provides the following gain structure for each channel:

Microphone Input XLR: 45dB of variable gain (+14dB to +55dB)

Instrument HiZ Input TS ¼” (channels 1 and 2 only): 45dB variable gain (+8dB to +50dB)

Clip Indicator. The clip indicator will light up if your input signal from the XLR (Mic) or ¼” (line) reaches +18dBu (0dBfs). At this level, your mic preamp/line trim signal may not exhibit signs of clipping such as distortion. However, this level would cause the A/D (analog to digital) converters to clip. Therefore it is highly recommended that you do not allow your converters to clip (the clip indicators to light up) as the sound quality would not be desirable.

4.Main Level. This knob allows control over the output level for the MAIN CR OUTPUT 1 and 2 on the back of the FIREBOX. It has a range of -80db to +10dB.

5.Headphone Symbol and ¼” Jack. This is where you connect your headphones.

6.Phones. The Phones knob controls the amount of volume going to the headphone output on the front of the unit. Notice the volume indicator goes to 11 (loud). Use this setting with caution.

7.Red-Blue Power/Sync Light. This light is a clock (sync) indicator. It lets you know if your unit is receiving word clock correctly. Word clock is the manner by which digital devices sync frame rates. Proper word clock sync prevents digital devices from having pops, clicks, or distortion in the audio signal (due to mismatched digital audio transmission).

Blue – solid sync

Red – sync not present.

Flashing Red and Blue – external sync not present

17