Originally Posted by JimWilson
Originally Posted by DonH50
I am not sure what you mean by "pure". If both ends (and the cable) are fully differential then you gain common-mode rejection and potentially lower even-order distortion (not all XLR I/O circuits are fully differential; some are quasi-differential, even on pro equipment). Differential circuits tend to be noisier, however, and distortion is so low that going from inaudible to more inaudible may not buy much.
FWIWFM, in the high-speed large-signal world of GHz and up circuits that I play in for my day job, everything is differential. Except when doing pro sound, XLR is not a factor for me in choosing my audio gear.
These aren't Ghz signal paths though, so I'm not certain high-speed requirements apply to subwoofers.
Sorry, I was not clear. I was trying to make the point that differential circuits are a requirement for RF, not so much for audio. We are saying the same thing.
I wasn't really sure what word to use when I posted that, which is why I quoted 'pure' in the first place. It seemed endemic, but not as descriptive as I would have liked. The crux of what I was attempting to convey is that XLR is not just for long cable runs; it's also for better signal quality. Is the difference audible? Who knows. Regardless, I suspect there's a reason all studio monitors have XLR inputs, and it's probably due more to the need to have pure signal paths than anything else. Studios rarely have exceedingly long cable runs, so that's more than likely not the overriding concern.
"Pure" is as good as any, I just don't think it's true, at least IME. I could be wrong, happens at least once an hour (more often when talking to my kids and wife
). Except for some piddling now and then, my pro audio work (live and studio) is years ago, but again IME we used XLR because of noise rejection, not because the signal had lower distortion. Pro gear generally has more headroom but that has nothing to do with the XLR, except that for a given supply rail you can get twice the (differential) voltage swing (and rt(2) more noise, natch). Studio runs are not as long but with all that gear it's a noisy environment and ground loops are
endemic so XLR makes sense. A lot of studio gear (and a lot of live gear, for that matter) includes a switch to lift the ground on one end of the XLR to reduce ground coupling. And, you do get that factor of two increase in signal for the same supply, a benefit when lots of headroom is needed. It does not necessarily improve distortion or noise floor, however. There are two many variables for me to say one or the other is better. I have had good and bad examples of each (balanced and unbalanced equipment).
All IME, IMO, etc. And as usual there are always cases in the home where XLR makes sense, and there are plenty of consumer components that have XLR outputs as well. - Don