Intel Fireface 800 - Manual (Page 47)

User's Guide Fireface 800 © RME
47
25. Analog Inputs
25.1 Line Rear
The Fireface has eight 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 800 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 'standardized' studio levels do not result in a (often desired) full scale level, but take some
additional digital headroom into consideration. The amount of headroom is different in different
standards, and again differently implemented by different manufacturers. Because of this we
decided to define the levels of the Fireface in the most compatible way.
Reference 0 dBFS @ Headroom
Lo Gain +19 dBu 15 dB
+4 dBu +13 dBu 9 dB
-10 dBV +2 dBV 12 dB
With +4 dBu selected, the according headroom meets the latest EBU recommendations for
Broadcast usage. At -10 dBV a headroom of 12 dB is common practice, each mixing desk op-
erating at -10 dBV is able to send and receive much higher levels. Lo Gain is best suited for
professional users who prefer to work balanced and at highest levels. Lo Gain provides 15 dB
headroom at +4 dBu nominal level.
The above levels are also found in our ADI-8 series of AD/DA converters, the Multiface, and
even in our Mic-Preamps QuadMic and OctaMic. Therefore all RME devices are fully compati-
ble to each other.
25.2 Microphone / Line Front
The balanced microphone inputs of the Fireface 800 offer an adjustable gain of 10 to 60 dB.
The soft switching, hi-current Phantom power (48 Volt) provides a professional handling of con-
densor mics. The mic preamp's discreet Class-A front end guarantees a superior sound quality.
With the balanced Line input, which can be used alternatively or at the same time as the micro-
phone, the Fireface 800 becomes even more flexible. 10 kOhm input impedance, stereo TRS
jack and adjustable input sensitivity in a range of 50 dB – this all guarantees that the front-side
Line inputs can be used perfectly with keyboards, sampler, active guitars and much more.
The Line inputs handle levels from –28 dBu up to +22 dBu. Two LEDs display a present signal
(from –45 dBFS on) and warn against overload (-2 dBFS).
Channels 7/8 can be switched between Line rear, microphone, and Line/microphone simultane-
ously in the Settings dialog. The front Line input can be used simultaneously with the micro-
phone input. This way, up to three different sound sources (Line rear, Line front, microphone)
may be recorded at the same time on one channel.