dr.larkos wrote:Within your context, I gather, the term "symmetrical" is not meant as a synonym for "differential" but as a distinct word indicating a specific characteristic of the "differential" signal, namely, that the +/- components of the "differential signal" are in phase: no phase errors, to the extent physically possible, all through the complete output path from DAC to XLR male connector. Am I correct?
Like the vast majority of DAC-chips, the ones used in the ADI-2 series all put out a symmetrical, balanced signal, hence an in-phase (+) AND out-phase (–) signal.
These two signals are both transferred completely independent and identical through ADI-2’s analog processings, the Reference Level switching and output buffer, to the XLR outs.
The result is a fully symmetrical, electronically balanced output with pin 2 / (+) and pin 3 / (–) carrying an active anti-phase to each other signal.
According to @MC’s posting there‘s a internal circuit that removes common mode noise from the DAC:
https://forum.rme-audio.de/viewtopic.ph … 13#p149113
The output is NOT servo-symetric, if one polarity is shorted to ground the other polarity is NOT boosted by factor 2.
Therefore neither pin 3 (nor pin 2) should be connected to ground when used unbalanced, as this signal shortcut has slight detrimental effects.
The rear TRSs present impedance-balanced outputs.
Only the (+) / Tip contact carries an active signal.
The (–) / Ring contact is connected to ground through a resistor equal to the (+)’s impedance.
This way the TRS can be connected to unbalanced inputs without further measures, e.g. with a simple TS-cable.
Connection to a balanced input with balanced cables keeps the possible noise suppression advantages of this type interconnects.
