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20. Analog Inputs
The ADI-2/4 Pro SE has two analog line inputs that can operate with levels up to +24 dBu. The
electronic input stage uses a servo balanced design which handles unbalanced (TS jacks) and
balanced signals (TRS / XLR) correctly, automatically adjusting the level reference.
When using unbalanced cables with the XLR inputs, pin 3 of the XLR jack should be con-
!
nected to ground. Otherwise noise may occur, caused by the unconnected negative input of
the balanced input.
To use the inputs as unbalanced RCA: simply insert a standard TS male to RCA female adapter.
Now any RCA / Cinch cable can be easily used with the ADI-2/4 Pro SE.
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 ADI-2/4 Pro SE internally uses hi-quality electronic
switches, which allow for an adaptation to all existing studio levels.
Additionally a digital Trim Gain of 0 to +6 dB, in steps of 0.5 dB, can be applied, to precisely match
the output level of external gear. The 6 dB of digital gain makes the whole range between -5 dBu
and +24 dBu available in steps of 0.5 dB.
Trim Gain can also be used to increase the input sensitivity to -5 dBu for 0 dBFS. Note that digital
gain reduces the basic signal to noise ratio of the ADI-2/4 Pro SE by the amount of the gain. In
real-world applications this will hardly be any problem, as the worst case SNR of -112 dBu (+6
dB Gain @ +1 dBu) is very difficult to achieve from most analog sources.
Ref
Vrms
+24 dBu
12.28
+19 dBu
6.9
+13 dbu
3.46
+7 dBu
1.73
+1 dBu
0.87
The analog inputs also feature automatic overload protection. Activating the option Auto Ref
Lev(el) changes to the next higher reference level when overloads are detected.
When RIAA mode is active the choice of Ref Level and Auto Ref level are not available.
21. Analog Outputs
21.1 General
The rear TRS outputs, XLR outputs and the front outputs PH 1/2 are fed from the same DAC,
hence carry the same signal - channels 1/2. They all have individual driver stages with different
output levels, see next chapters for details.
All outputs feature mute components to suppress power on/off noise, even when power fails in-
stead of switching the unit off via the standby button.
SNR and THD values as well as frequency response are nearly identical on all analog outputs.
All three phones outputs feature mute relay, over-current detection, DC protection, plug detection
and DSP control, like auto assigning volume, volume ramp up, auto balanced mode, dual phones
mode, user interaction at overload detection, and low impedance level meter auto scaling.
52
Digital Gain +6 / 0 dB
+18 dBu to +24 dBu
+13 dBu to +19 dBu
+7 dBu to +13 dBu
+1 dBu to +7 dBu
- 5 dBu to +1 dBu
User's Guide ADI-2/4 Pro SE - v 1.0
Vrms
+18 = 6.15
+13 = 3.46
+7 = 1.73
+1 = 0.87
- 5 = 0.44
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