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Balanced vs. Unbalanced - What does it mean?

I have a McIntosh MC402, I am using the Unbalanced inputs - my dealer hooked it up for me. Everything sounds fine but I am wondering about the Balanced input. When do they get used? Does it sound different? Which is best?
cam3366
6550c
393 posts
 
True diff. balanced circuits use "common mode rejection" to reduce the noise floor of the equipment and increase signal to noise ratio. (not necesarly just line noise and RFI)

Some (many) components have XLR connections tacked on the back, but the circuits are not true diff balance designs and many times they may actually sound better just using the RCA jacks because the signal path is actually shorter.

Generally, the input inpedance is not the same for the XLR and RCA jacks, so things may sound different.
6550c
393 posts
 
Almarg - Actully, Audio Research, at one time sold an active component just for converting from single ended to balanced (and the other way too). Did anyone ever buy one of these. (I think it was at the time of the LS5 preamp that only had XLRs and NO RCA jacks.)
shadorne's avatar
shadorne
7,477 posts
 
It would be a concern if the outputs of a pro-oriented source component, or a pro-oriented equalizer or processor, were fed into the line-level inputs or tape inputs of a consumer-oriented preamplifier

Exactly. If you use a Benchmark DAC1 with the XLR ouput into a consumer grade preamp or poweramp then you will probably need to set the attenuator pad in the DAC1 to drop the signal level by 20db. (This is wasteful of the higher ouput capability of pro balanced lines. It is generally a good rule of thumb to use higher level signals to give you more dynamic range over the equipment noise floor. It may well be enough of a difference to be able to hear something very soft or 60 db down versus not hearing it at all...)
martykl
3,578 posts
 
I'm not sure if this has already been noted here, but I'd like to clarify: You cannot be sure that an unbalanced output can be effectively run into a balanced XLR input merely by the simple addition of a physical adaptor. ARC gear will not work correctly in this set-up. That is why ARC sold their transformer.

IIRC, ARC's power amp protection circuitry will be triggered by the unbalanced input signal and severely limit the amp's power output. This is evidently a function of the protection scheme that ARC uses in its power amps. Other brands may (or may not) have similar problems. Probably best to check with the manufacturer.

Good Luck.

Marty
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