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Single ended vs xlr balanced

I have switched backwards and forwards (going slightly mad in the process) testing (long run) interconnects.
I know some sound engineers, and they tell me I am probably persuading myself that balanced is better than single ended and THERE IS NO REASON WHY SINGLE ENDED CAN SOUND INFERIOR TO BALANCED. Sorry to use capitals but this seem to be a fair summary of the be all and end all of technical discussion. If I was to guess however, my mind would tend to follow the technical opinion not go against it, surely? In my mind the balanced is a deeper more airy sound, just better presence all round. The technical response is that I am not comparing like with like, as the balanced runs at higher voltages and subsequently higher volume (6db). I had a shock at this news and found out therefore by accident that my Bryston 28bsst2s amps have a switch upping the output from 23 to 29db to compensate. Also did I hear properly that Bryston kit is set up preferring balanced? My processor is a Bryston sp3 so maybe my preferred balanced system  is what I needed anyway. But it is odd that a reputable company like Bryston would have such a policy (if it has foundation) and not stress that on their literature. If my system can be adjusted for speaker levels then volume output is irrelevant - or is it if that higher voltage has some effect?
And don't get me started on aes/ebu vs spdif! The aes to me is noticeably superior for the same reasons as the rca vs xlr debate. Then hdmi vs spdif ... (Time for my medicine ........)
So my question is - forgetting technicalities which can get more and more complicated by the minute  - do other peoples' ears agree with mine?
tatyana69

Showing 6 responses by erik_squires

erik_squires
16,468 posts
 
It's important to note that pro gear is different than consumer gear. Pro gear usually converts the balanced signal to single-ended immediately, and feeds it's inputs with that, until it's output, when it is again balanced by adding a negative phase op amp stage to drive the (-) pin.

Consumer gear may be fully balanced, meaning you have two sections working in opposition from input to output, the idea being that any crossover effects or distortions will be canceled out. In these cases it may be better. Also, some amplifier inputs I've seen such as from B&O and Hypex are really balanced input only. There's a paper that goes into more detail at the Hypex website on balanced inputs.

There is one big reason why balanced may sound better that your engineer friends aren't thinking about.  Ground loops. Balanced systems don't ground a pin, meaning if there's any ground voltage imbalance between a pre and amp, it won't be part of the signal chain. With an RCA connector it almost always must be. When I worked in pro gear, we had to deal with single ended signals, but always kept the signal ground disassociated from the chassis and safety ground.  Not a lot of consumer gear goes through this much effort.

Best,

Erik
erik_squires
16,468 posts
 
I should also say, there are mechanisms which MIGHT make balanced sound better. That's different than saying it WILL. :)

The truth is, if you can't hear it, it's just academic. Make your own ears and wallet happy. :)

Best,


Erik
erik_squires
16,468 posts
 
Pro grear uses a ground lift switch, which completely disconnects the ground, leaving only the (+) and (-) signals connected. Usually a totally benign or definite improvement.

There’s no way to do this with an RCA cable, except to use the safety ground as your reference point, kind of a scary thing from a noise and quality perspective.

You can do some cute things like using a balanced cable (shield plus 2 conductors) and connect the shield only at the preamp, while the GND conductor gets connected at both ends. This may minimize EMI / RFI noise pick-up, but the ground loop problem remains the same. Another "tricky" thing to do is in a stereo pair only use 1 conductor in total for the ground. For instance, Left has the signal plus ground but right only has the ground. These are just tricky tweaky things that I don't expect would do much good.

One other design trick is to treat the receiving end of an RCA connector as if it were balanced. That is, instead of connecting the shield at the amp end, you insulate it, and either use a transformer or instrumentation buffer.  It's also nice in that some transformers sound really great. :) JR does this to warm up some of his amps.

Best,

Erik
erik_squires
16,468 posts
 
@mward

The input buffers might be making all the difference there. Depends.

@almarg is right, impedance differences on the input are good indicators of the circuit paths not being the same.

I’ve seen some amps whose only claimed to balanced inputs was the XLR plug, but otherwise was completely single ended. However, most pro gear is at least truly balanced inputs, but single internally. That is, they use mirror imaged op amps or a transformer on the input to convert. That can make a lot of difference. The Op Amps can sound better because they work in opposition and cancel errors, the transformer in adding some warmth, and in both cases common-mode noise is greatly reduced, not to mention the ground loop issues previously discussed.

There is also some anecdotal evidence that merely raising the impedance of a input circuit sounds better. Whether it's universally true, or only sounds better for less robust designs is unknown. The math says the differences should be infinitesimally small with most well designed gear.

Sadly the Parasound A23’s I owned were of the former, I believe, and just had convenience plugs. I was unable to tell the difference in using either one. My current amps are XLR only , and truly balanced inputs, so I have no way to compare.

Best,

Erik
erik_squires
16,468 posts
 
@cleeds

RCA's don't lock in place, they more "squeeze in place" vs. EVERY XLR locks.

I think Parasound is the exception, and they had to go seriously out of their way to find jacks that don't lock. Maybe not in the JC line, but in the lower end Halo parts. :)

Yeah, the fact that XLR doesn't need ground at all to work is one of the superior features. The other one is measured as CM rejetion, or Common Mode.  This is where a  signal is induced from outside. Balanced cables are SUPERB at this compared to single-ended.

In a home would that ever matter?  Very situation dependent.  Still, just to save myself the trouble I always run my subs this way.

Best,


Erik
erik_squires
16,468 posts
 
@cleeds

Sorry, and thanks for contributing that. :)

I'm afraid it's still too early for me and I got into a silly semantic argument. :)

The point was more that you can assume every XLR cable you buy will lock, but it's a specialty thing for RCA connectors.

Best,

Erik
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