Balanced vs Unbalanced Audio

[Dougal]

Apologies if this is a duplicate thread (I searched the subject beforehand to no avail), but I wondered what fellow forum members opinions are on the subject of balanced vs unbalanced audio?
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Are balanced connections unnecessary for home listening?
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The reason for asking is, I recently heard a CD player whose performance via balanced XLR output sounded superior to the unbalanced output (unbalanced was fatiguing).

This made me wonder whether balanced connections have an inherent superiority, as suggested by professional audio practice, that would be apparant in the domestic environment.

[Pluto]

Are balanced connections unnecessary for home listening?

A balanced connection achieves is greater immunity to electromagnetic interference. The interface itself is generally designed to be capable of driving long cable runs, that is, a very low output impedance coupled with the ability to deliver significant current if the load so demands - in other words, a good balanced output interface has more in common with the output of a power amplifier than a typical domestic pre-amplifier.

There is no reason that a balanced line should, per se, sound any different to an unbalanced one, but the former may well benefit from the need to conform to a certain standard. Likewise, the XLR connectors generally used are far more robust and reliable than any RCA phono connector. In fact, phono connectors are pretty awful things (no matter how much you pay for them) and are best avoided if possible. XLRs have a far larger contact area, high pressure contacts and are inherently self-cleaning.

So while there is no reason that a balanced connection should be superior to an unbalanced one in and of itself, it is highly likely that the implementation is, in many cases, better.

[Dougal]

Many thanks for your post, Pluto - much appreciated.

I now cannot look at my unbalanced amplifiers without an acute attack of audio nervosa! Their days are numbered I think.

{Moderator's comment: hope that you are kidding. Unless you live next to a radio transmitter, balanced/unbalanced will not make a scrap of difference. Balanced only benefits when the cable runs are very long, the signals are weak (like microphones) and there is strong local interference. More circuitry is needed to balance/unbalance and logically that can't benefit sonics can it.}

[Dougal]

I'm half-kidding...

The moderator's comment has allayed my anxiety, such as it was. Many of the revered components throughout hi-fi history have never come within reach of an XLR socket, so there is nothing really to be worried about.

But one thought does haunt me: Forgive my paraphrasing, Alan, but you have said we should regard audio equipment as a capital investment that functions reliably day-to-day. In the case of amplifiers, many of the ones that follow that principle are to be found in the pro-audio world, replete with balanced XLR connections. These are the real workhorse, 'set and forget' pieces that once installed can be safely taken for granted.

So even if there are no sonic benefits from buying balanced equipment, there may be some advantages when it comes to reliability and ease of service.

I do agree with the comment that more circuitry cannot be beneficial, although it is worth bearing in mind that Focal and B&W make precisely this point on the subject of crossovers! Sorry Alan...

[Vlado]

My experience with balanced amps/preamps is other. It depends on manufacturer. First I would like to exclude those which are fitting the real panel with XLR connectors and using just the hot and ground for the signal... other use an opamp to sum the hot an cold to drive the amp. So those are 'marketing' balanced inputs.

With the real balanced amps/preamps/CD players, the situation is a bit different. The 1st statement in Pluto's reply is fact, but the sound of some brands is different - better (more air, space and resolution in the recording) when the components are connected with XLR's; I have no idea why (Electrocompaniet, Ayre....) The sound of some other manufacturer gear is absolutely identical whether using XLR or RCA (Bryston....)

The world is not black and white and the measurements do not give always an resonable explanation.

[garmtz]

There is a difference between using an unbalanced or balanced CABLE or using equipment that has a balanced or unbalanced ARCHITECTURE.

To make use of all the advantages of balanced, the source and end point both need to be built up 'dual differential'. This means that the positive and negative halves of the signal are handled independantly in the signal path. By handling one of them from the beginning in negative phase, reversing the phase again of that same channel and adding the halves together in the end of the chain will cancel out 'common mode noise' (noise common on both halves of the signal). Pro audio uses this working principle to have the least noise as possible. Coincidentally, both Ayre and Electrocompaniet use 'real' balanced circuits, so make use of the 'dual differential' advantages.

Most equipment fitted with XLR connectors, but internally, they are built up 'single ended' (unbalanced). So balanced signals need to be converted to unbalanced and vice versa. This conversion alone can result in WORSE sound! So always try the balanced connection first, it might not even sound better! In the best case (when the component in not really balanced from beginning to end), it will sound the same. Sometimes, the balanced can sound better than unbalanced just because the XLR cable is just a better cable than the unbalanced one!

Just having a balanced CABLE might reduces noise incurred during transport because of the shielding with is not common with the signal ground (in unbalanced cables, signal ground and shielding are 'tied together', in balanced, they are separate).

[Pluto]

... other use an opamp to sum the hot an cold [with an appropriate phase inversion] to drive the amp. So those are 'marketing' balanced inputs.

...and what's wrong with this? The point of the balanced input is to reduce pick-up of electromagnetic interference over the length of the 'journey' from the source. Provided the common mode rejection ratio adequately high, the primary objective of the balanced input is fulfilled.

The concept that an amplifier design ought to be balanced throughout make things unnecessarily over-complicated and is little more than a marketing gimmick.

[Vlado]

...and what's wrong with this? The point of the balanced input is to reduce pick-up of electromagnetic interference over the length of the 'journey' from the source.

I don't say that's wrong.

[Dougal]

Interesting comments - many thanks for your posts.

I had forgotten that I have, in the past, heard fatiguing sound via balanced equipment. So balanced does not automatically mean 'non-fatiguing'.

In case you think the word 'fatiguing' is a vague cop-out, my understanding and experience of this quality is the perception of the music being overlaid by a barely perceptible, but irritating continuous high frequency tone. A bit like the frequency emitted by a light bulb on the point of failure, but right at the limit of audibility. This also has the effect of 'constricting' the music because perhaps the brain is being stressed by this invasive by-product, distortion (or whatever it actually is) and cannot 'process' the music as normal.

[hifi_dave]

I totally agree with Garntz, post number 6 above.

Very little Hi-Fi equipment is manufactured to make the most of balanced because of the complexity and cost. The vast majority of Hi-Fi products with 'balanced' are just single ended but with XLR connectors or, worse still, single ended with an extra circuit to convert to 'balanced'. This often results in a worse sound.

[Pluto]

...single ended with an extra circuit to convert to 'balanced'. This often results in a worse sound.

This is how the vast majority of professional kit is made. The concept of a fully balanced design from A to Z is difficult, over-complicated and consequently, likely to be less stable than a good, unbalanced design. It is the interface and its associated long cable runs that benefit from the balancing, nothing more.

The design of a totally transparent balanced-unbalanced converter (and vice versa) is child's play these days; if a balanced interface sounds different, then either it (or its unbalanced partner) has been deliberately designed to do so or there is a fault condition. Also, remember that the RCA phono connectors used on unbalanced interfaces are poor in most important respects; it is the fundamental design that's bad - not something that can be corrected by spending lots on cables and connectors.