User's Manual

User’s Guide ADI-2 DAC v2.2 © RME
37
!
19.3 Line Out XLR
The ADI-2 DAC has two balanced analog outputs that can operate at levels up to +21.5 dBu
(+19 dBu with Volume set to +2.5 dB). The short circuit protected, low impedance line outputs
are available as XLR jacks on the back of the unit.
The XLR line outputs do not operate servo balanced! When connecting unbalanced equip-
ment, make sure pin 3 of the XLR output is not connected. A connection to ground might
cause a decreased THD (higher distortion) and increased power consumption!
To maintain an optimum level for devices connected to the analog outputs and to maximize the
dynamic range, the ADI-2 DAC internally uses hi-quality electronic switches, which realize a
hardware based Reference Level selection in steps of 6 dB over a range of 18 dB: +1 dBu, +7
dBu, +13 dBu and +19 dBu.
The analog outputs also feature a mechanism to set the reference level automatically. Auto Ref
Lev(el) maximizes the signal to noise ratio when using the Volume knob. It changes to the next
higher and lower reference level setting when the gain chosen via the Volume knob would sug-
gest to set a better fitting value, with optimized signal to noise ratio.
Example: Ref Lev is set to +19 dBu, Volume is turned down to -20 dB. The effective signal to
noise ratio at the XLR output is now 120 dB minus 20 dB = 100 dB (RMS unweighted). While it
is unlikely that any noise will be audible, changing the Ref Level to +1 dBu would need only a
Volume setting of -2 dB to achieve the same level or volume. The effective SNR then becomes
117 minus 2 = 115 dB (15 dB higher). Such settings are usually done manually by the user.
Auto Ref Lev takes over this task, working in both directions when turning Volume up or down.
Notes on Auto Ref Level
:
This technique includes switching of hardware elements (like when doing it manually) and is
therefore not free of click noise. To prevent distortion the threshold for a Ref Level change takes
EQ gains into account. Auto Ref on the Phones output will be inactive when Line Out and
Phones out are set to work simultaneously, and Auto Ref is enabled on the Line out.
19.4 Phones Out
The stereo phones output is available on the front as 1/4" TRS (stereo) jack.
Phones has two hardware reference levels: Low Power which equals +7 dBu (1.73 V), and High
Power with +22 dBu (10 V).
SETUP – Options – Phones / DSD – Mute Line offers an option to turn off the rear outputs as
soon as a phone is plugged in. Default is vs. Phones, which means Line muted when plugged.
In case the output should operate as line
output, an adapter TRS plug to RCA
phono plugs, or TRS plug to TS plugs is
required.
The pin assignment follows international
standards. The left channel is connected
to the tip, the right channel to the ring of
the TRS jack/plug.