RME Fireface UCX II 40-Channel USB-B Audio/MIDI Interface - Manual (Page 40)

40 User's Guide Fireface UCX II © RME
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19. Analog Inputs
19.1 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 II internally uses hi-quality electronic
switches, which allow for a perfect adaptation of all rear inputs individually to the most often
used studio levels. The Fireface UCX II offers the following level references:
Reference 0 dBFS @ Max Gain 0 dBFS @
+19 dBu +19 dBu 12 dB +7 dBu
+13 dBu +13 dBu 12 dB +1 dBu
A reference level of +4 dBu can be set by using +13 dBu and adding 9 dB of gain with the Gain
knob in the TotalMix FX channel settings.
19.2 Microphone / Line Front
The two balanced microphone inputs of the Fireface UCX II offer a digitally controlled gain of 0
to 75 dB via XLR/TRS combo jacks. The gain range is 0 to 75 dB, adjustable in steps of 1 dB.
The soft switching, hi-current Phantom power (48 Volt), switchable per channel, provides a pro-
fessional handling of condensor mics. Up to a level of +18 dBu, the front XLR input can also be
used as balanced and unbalanced Line input.
The TRS jacks of the two combo jacks are free of phantom power and fully compatible to unbal-
anced (mono jack) sources. They have a fixed level attenuation of 6 dB. The maximum input
level is therefore +24 dBu, balanced and unbalanced.
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 will quickly rotate back to a gain that is appro-
priate.
While with extreme overloads distortion will occur for the fraction of a second before the level is
set correctly, AutoSet works quite well in real-world applications and prevents distorted record-
ings reliably.
Using stereo channels AutoSet operates ganged. AutoSet can be
activated in TM FX or directly at the unit in the channel settings. A
push on Encoder 1/2 toggles AS on/off.
As soon as AutoSet reduces the gain the label AS, shown in the front
display, changes its colour from black to blue.