User's Manual

User’s Guide ADI-2 Pro FS – v 2.5

21.2 Line Out TS 1/2

The ADI-2 Pro has two unbalanced analog outputs that can operate with levels up to +19 dBu.

The short circuit protected, low impedance line outputs 1/2 are available as 1/4" TS jacks on the

back of the unit. When inserting a stereo TRS connector the ring contact is connected to

ground.

Due to the unbalanced operation the TS outputs follow all Ref Lev settings, but stay at +19 dBu

when +24 dBu is selected. For Auto Ref Level see next chapter.

21.3 Line Out XLR 1/2

The ADI-2 Pro has two balanced analog outputs that can operate at levels up to +24 dBu. The

short circuit protected, low impedance line outputs 1/2 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, the ADI-2 Pro inter-

nally uses hi-quality electronic switches, which allow for a perfect adaptation of all outputs to the

four most often used studio levels +4 dBu, +13 dBu, +19 dBu and +24 dBu.

The analog outputs 1/2 (and 3/4) also feature a mechanism to set the reference level automati-

cally. 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 Vol-

ume knob would suggest to set a better fitting value, with optimized signal to noise ratio.

Example: Ref Lev is set to +24 dBu, Volume is turned down to -21 dB. The effective signal to

noise ratio at the XLR output is now 117 dB minus 21 dB = 96 dB (RMS unweighted). While it is

unlikely that any noise will be audible, changing the Ref Level to +4 dBu would need only a

Volume setting of -1 dB. The effective SNR then becomes 115 minus 1 = 114 dB. Such settings

are usually done manually by the user. Auto Ref Lev takes over this task, working in both direc-

tions when turning Volume up or down.

Notes

: 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.

21.4 PH Out 1/2

Channels 1/2 are also available on the front as 1/4" TRS (stereo) jack.

All outputs labelled 1/2 share the same Volume knob setting and the same hardware reference

level setting, with two small differences: as mentioned above the unbalanced TS output is

capped to +19 dBu, and the front output PH 1/2 has a 3 dB higher output level. So while it also

is capped at the +19 dBu Ref Lev setting, its real output level is +22 dBu.

This 3 dB gain turns +4 dBu into +7 dBu output level, +19 dBu into +22 dBu – only at the

phones jack PH 1/2. Reason: The output PH 1/2 becomes identical in level with output PH 3/4

(Hi-Power Off = +7 dBu, Hi-Power On = +22 dBu). Identical levels for both phones outputs are

required for balanced phones operation, but also simplify usage and setup.

Please note that PH 3/4 is the main phones output of the ADI-2 Pro. PH 1/2 is designed as ad-

dition and extra functionality. Sharing volume/level settings with the rear outputs some limita-

tions arise. PH 1/2 is simply not totally independent, and should therefore only be used when

really needed. The ADI-2 Pro issues a warning message when inserting a plug into PH 1/2.