Analog Inputs; Line Rear; Microphone / Line Front - RME Audio Fireface UCX User Manual

21. Analog Inputs

21.1 Line Rear

The Fireface has four balanced Line inputs as 1/4" TRS jacks on the back of the unit. The elec-
tronic input stage is built in a servo balanced design which handles unbalanced (mono jacks)
and balanced (stereo jacks) correctly, automatically adjusting the level reference.
When using unbalanced cables with TRS jacks: be sure to connect the 'ring' contact of the
TRS jack to ground. Otherwise noise may occur, caused by the unconnected negative input
of the balanced input.
One of the main issues when working with an AD-converter is to maintain the full dynamic
range within the best operating level. Therefore the Fireface UCX internally uses hi-quality elec-
tronic switches, which allow for a perfect adaptation of all rear inputs to the three most often
used studio levels.
The Fireface UCX uses the following level references:
Reference
Lo Gain
+4 dBu
-10 dBV
The above levels are also found in all other RME devices. Therefore they are fully compatible to
each other.

21.2 Microphone / Line Front

The two balanced microphone inputs of the Fireface UCX offer a digitally controlled gain of 0 to
65 dB via XLR/TRS combo jacks. The gain range is 65 dB, adjustable in 1 dB steps over a ran-
ge of 55 dB. The soft switching, hi-current Phantom power (48 Volt), switchable per channel,
provides a professional handling of condensor mics. Up to a level of +10 dBu, the front XLR
input can also be used as Line input.
The two combo jacks also allow for the usage of mono and stereo TRS jacks. The TRS inputs
have a fixed level attenuation of 11 dB. Based on the adjustable amplification from +0 dB up to
+65 dB, the sensitivity is +21 dBu down to –44 dBu, referenced to full scale of the AD-converter.
Therefore the TRS inputs are true full level Line inputs, and the unit can also be used as Line
amplifier.
The TRS jacks are free of phantom power.
Two LEDs display a present signal (from –60 dBFS on) and warn against overload (0 dBFS).
Channels 1 to 4 feature an automatic overload protection. AutoSet tries to keep a headroom of
6 dB. Levels higher than -6 dBFS will permanently reduce the gain. To check set the channels
to a high gain and apply an input signal. The button in TotalMix will quickly rotate back to a gain
that is appropriate. While AutoSet in the UCX is not exactly the same as in the RME Micstasy
(with extreme overloads distortion will occur for the fraction of a second before the level is set
correctly), it works quite well in real-world applications and will prevent distorted recordings
reliably.
Using stereo channels AutoSet operates ganged. AutoSet can be activated in the channel Set-
tings in TM FX.
38
0 dBFS @
+19 dBu
+13 dBu
+2 dBV
User's Guide Fireface UCX © RME
Headroom
15 dB
9 dB
12 dB