User's Guide ADI-2 © RME
7
7. Inputs and Outputs
7.1 Analog Inputs
The ADI-2 provides balanced Line inputs via Neutrik combo jacks, XLR and 1/4" TRS. The elec-
tronic input stage is built in a servo balanced design which handles monaural and stereo jacks
correctly. When used unbalanced it automatically corrects the gain by 6 dB.
When using unbalanced cables with XLR jacks, pin 3 of the cable's jack should be con-
nected to pin 1 (ground). Otherwise noise may occur, caused by the unconnected negative
input of the ADI's 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. To achieve this, RME's ADI-2 includes a discrete hard-
ware gain stage, directly in front of the AD-converter. Electronic switches of the latest technol-
ogy, which introduce no additional noise or distortion to the audio path, are used to control the
gain, and offer highest operating comfort. This way, the button INPUT - LEVEL allows a con-
vinient adaptation to the most often used studio levels -10 dBV and +4 dBu.
Level Meter
The 2-channel level meter with 6 LEDs each offers a useful display and check of input level and
overloads. The LEDs make use of different brightnesses for different levels, so levels in be-
tween are easy to read out. This technology allows the ADI-2 to visualize a range of –76 dBFS
up to –3 dBFS using only 5 LEDs.
The red OVR LED lights up dimmed at -2 dBFS, more bright at –1 dBFS. Reaching 0 dBFS it is
fully lit. A peak hold function of one second ensures better visualization whenever the highest
level is reached.
The table shows the level definition of
the Level Meter, based on 0 dBFS. The
actual input level in dBu can be calcu-
lated by adding the offset caused by the
current choice of Input Level. Set to Lo
Gain 19 dB have to be added, at +4 dBu
a value of 13 dB has to be added (see
below).
Input Level definition
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 ADI-2 in a most compatible way. The headroom of the ADI-2
is defined according to the chosen reference level.
Reference 0 dBFS @ Headroom
Lo Gain +19 dBu 15 dB
+4 dBu +13 dBu 9 dB
-10 dBV +2 dBV 12 dB
At +4 dBu a headroom of 9 dB offers a problem-free operation with most devices, and meets
the latest EBU recommendations for Broadcast usage. At -10 dBV 12 to 15 dB headroom are
common practice, each mixing desk operating at -10 dBV is able to send and receive much
higher levels. Lo Gain allows to work with high levels, best suited for professional users who
prefer to work balanced and at highest levels.
LED Dim Medium Bright
OVR -2 -1 0
-3 dB -5 -4 -3
-6 dB -8 x -6
-12 dB -24 -18 -12
-30 dB -45 x -30
-60 dB -80 x -60
(62 pages)
(42 pages)
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