Originally Posted by
petrat
I remember KK writing that 'in all cases, balanced is preferable to unbalanced' ... but ime, as stated above, it all depends on the implementation. Actually, Neil, I reckon my current EAR amps sound a smidge better when connected together using the balanced connectors, but my Rega cdp is clearly superior via its rca outputs (despite Rega insisting the XLR outputs are better). Might re-visit the EAR rca connections in light of your comment, but the implementation that TdP uses takes both signals through the same isolating transformers, so shouldn't be any difference really ... maybe it's differences between interconnects that are the culprit?
There is no reason to presume balanced should be better than unbalanced.. it's just yet another hi fi myth.... Much of the time balanced means a more complicated signal path with more active devices in the path, or a passive transformer with all the ills of transformers.
If there is no mains hum or other interference present when using unbalanced then there isn't even the advantage in noisy environments to be gained from going balanced.
The whole point of balanced is that in pro environments when many dozens of microphones, mic pre amps, effects units, etc etc may need setting up quickly and may well need very long leads (like 50 yards or more) from a stage or studio then everything may be just plugged in with little worry of mains hum, earth loops etc.
In a domestic setting we can take care to position equipment sensibly, avoiding putting a phono stage on top of a power amp for example, where the hum field from the power amps transformer will reach beyond the casework and could cause hum to be picked up by the phono stage. We also can, most of the time, get away with interconnects of a meter or two and take care not to run them alongside a mains lead etc. Under these domestic conditions there is simply no need for or advantage to balanced. As I said it is often a disadvantage in as much as there can be considerably more gubbins in the signal path!
It strikes me as odd, or at least inconsistent, that folks will one minute be all "oh we can't have nasty op amps in the signal path.. it must be discrete, or better still valved.." and then not give a fig if the balanced interface involves adding six op amps per channel...
The main potential advantage of balanced, to me anyway, is the potential to avoid all earth signal current issues, but if the unbalanced circuitry is well designed it is not an issue anyway. If one looks up "pin 1 problem" it can be seen that even balancing is not without issues here!!
The best and most pure balanced circuitry IMHO is where the circuitry is intrinsically balanced by design throughout... This can maximise advantages such as cancellation of even order distortion and increasing headroom. Even this though will often mean a much more complicated signal path and in fact will often mean the duplication of circuitry ie often there will be an amp for the "hot" signal and another amp for the "cold" signal for each channel... Circuitry such as this is is the most likely to really resent being used unbalanced though!!
It's a big subject when you really look into it. In many ways transformers are best ie maximum CMRR over widest frequency range, greatest tolerance to overload and maintaining certain behaviour when used unbalanced and one input is either left open or shorted. They also greatly simplify things! BUT, personally I would never put a transformer in the signal path as they have too many imperfections!
In pro audio certain pieces of equipment have legendary status mainly because of the colouration they add to the signal! "nice", euphonic colouration is what we're talking here of course. Much of this colouration comes from the transformers used in the balanced outputs and inputs. A producer or engineer may well choose a mic pre known to sound especially warm and a bit rolled off at the top end if recording an artist with a really harsh voice... and that's an "artistic choice" I guess...
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