User's Guide
ADI-2 FS © RME
11
8. Digital loop-through (DIG)
The ANALOG INPUT - LEVEL button offers a fourth position,
DIG
. In this state the ADI-2 FS
works in digital loop-through mode with analog DA monitoring. The AD converter is not in use.
The level meters show the audio level of the digital input signal.
Since the digital input signal appears simultaneously on both digital outputs, DIG enables the
ADI-2 FS to be used as format converter and distributor. For example, an ADAT input signal
can be simultaneously sent out as SPDIF coaxial and SPDIF optical. An SPDIF signal can be
converted converted into ADAT, but at the same time sent out as SPDIF again. With this type of
digital inserting, the signal is completely recreated by the ADI-2 FS in a bit-accurate manner,
and freed from jitter by its SteadyClock FS. A use as a signal refresher for cable extension is
one of its many possible applications.
In all these cases, the DA converter remains active, allowing the digital signal to be played back
and monitored locally.
9. Analog loop-through (ANA)
The ANALOG OUTPUT - LEVEL button provides a fourth position,
ANA
. In this state the ADI-2
FS operates in analog loop-through mode with digital monitoring (AD-converter). The DA-
converter is not in use. The block diagram in Chapter 13 shows how mode ANA works. The
analog input signal is not passed directly between the input jack and the output jack, but travels
through the entire analog input and output stage. Only the AD- and DA-conversion is bypassed.
The analog input and output stages of the ADI-2 FS (in fact of all RME devices) have
significantly better technical data than the AD- and DA-converters used. With barely
measurable distortion, very low noise and extremely wide frequency response, passing through
these stages can by no means be seen as a degradation of the analog signal. Instead, the
advantages of active loop-through far outweigh the insignificant drawbacks, as the servo-
balanced input stage with level adjustment, the multiple balanced and unbalanced output
stages with level adjustment, and the headphone output with its own volume adjustment are all
active now, turning the ADI-2 FS into various, useful tools:
x
Analog impedance converter
x
Analog level adaptation
x
Analog balancer (unbalanced to balanced and vice versa)
x
Analog distribution amplifier
The new option ANA which implements an analog bypass from the analog input to the analog
output, gives the ADI-2 FS a cornucopia of possible uses. For example, if ANALOG INPUT -
LEVEL is set to +4 dBu and ANALOG OUTPUT - LEVEL is set to +19 dBu, the ADI-2 FS ampli-
fies the analog input signal by 15 dB. At the same time, it sends it out electronically separated to
three different outputs.
Since in this mode the analog output is no longer connected to the DAC, the entire analog
headroom is available, with a maximum output level of +22 dBu (balanced). Even the input can
now be fed undistorted with up to +22 dBu. ANALOG INPUT set to +19 dBu and ANALOG
OUTPUT set to +4 dBu attenuate such a signal by 15 dB.
Additionally the AD-converter is also active and usable. As long as one does not 19
dBu input level, the analog signal can also be picked up digitally and undistorted.
Activation: Press the key ANALOG OUTPUT - LEVEL several times until no LED lights up. After
one second, the ANA mode is activated and the LED lights up. To deactivate, select the ANA
mode again and wait one second.
