Do I really need to concern myself with Balanced connections?

[NorthStar]

1. Mine is!!


2. What struck me as odd though is that DartZeel measures better in single-ended than balanced.

1. Wise axe! {I used to rent a place on a beach, with lake view, where the main room was a Music Jamming Room, with tons of electronic stuff, and microphones, and instruments, and feet and feet of wires/cables, ...}

2. I am not.

 

[microstrip]

(...) Ask any conscientious preamp designer, and the less parts used in a preamp the better it is for a lot of things, including sound quality with less extraneous sound introduced in the signal path.
Besides, well designed single-ended products are less expensive (in general), because they use less parts indeed.
And there is simply no such thing as parts that have no sound. (...)

Bob,
Surely the many designers of non balanced preamplifiers do not agree with you.

In your analysis you are forgetting the importance of power supply in most designs - some designers even say that the power supply is 90% of sound quality. The power supply in non ideal, and its "faults" leak into the audio circuit output. As it leaks in similar ways to both phases it is a common mode signal and can be eliminated easily by subtraction at the input of the receiving device. Common mode distortions can also be cancelled. We may consider that as the designer does not have to think about this common mode problems, he is free to use simpler circuits with better sound.

Some one referred the Audio Research REF3 - it is just one preamplifier that sounds and measures much better in balanced mode that in single-ended mode.

All solutions have pro and against - there are no clear winners in these matters.

 

[NorthStar]

Bob,
Surely the many designers of non balanced preamplifiers do not agree with you.

Micro, I never said the opposite, and they can say all they want, they are free to their own discord of complications, ...and calculated & balanced financial gains?

In your analysis you are forgetting the importance of power supply in most designs - some designers even say that the power supply is 90% of sound quality. The power supply in non ideal, and its "faults" leak into the audio circuit output.

First, that wasn't an 'analysis'.
Two, I did not forget the Power Supply; I simply didn't mention it.
But you're right, power supplies matter, so are the circuit designs.
...And quality parts count, and simplicity.

As it leaks in similar ways to both phases it is a common mode signal and can be eliminated easily by subtraction at the input of the receiving device. Common mode distortions can also be cancelled. We may consider that as the designer does not have to think about this common mode problems, he is free to use simpler circuits with better sound.

'Phase', now you are introducing a new subject into the equation.
Inverting phase or not?
Not inverting phase adds more parts, and more parts adds complexities, and complexities fight against simplicity by adding unwanted and 'unnatural sound signatures'.

All solutions have pro and against - there are no clear winners in these matters.

100% agree. But going Balanced is still a solution looking for a problem.
Balanced just adds complications to the design.

 

[mep]

But going Balanced is still a solution looking for a problem.
Balanced just adds complications to the design.

I don't agree with your statement one bit. Balanced audio was a solution to a very real problem in recording studios where long cable runs and hum were a real issue. If they didn't have benefits for regular audio systems, we wouldn't see them being used.

You keep touting the odd-ball gear that measures better in unbalanced mode than in balanced mode. I could be wrong, but I think these are the exceptions and not the norm as by design, the balanced gear should have better measurements. Balanced gear is typically more quiet and has more gain than single-ended circuits which is usually highly desirable. Is balanced gear more complicated? Yes. Does it have real world benefits? Yes.

 

[DonH50]

Hmmm... If the design uses op-amps, balanced may require extra components. If discrete, the number of components should be essentially the same, and the differential (balanced) design should offer better rejection of even-order harmonics and higher CMRR/PSRR. Most of the discrete SS preamps and almost all power amps I have seen above the very cheapest use balanced circuits internally, converting at the input stage and switching back to single-ended at the output stage. That said, I admit that relative to most of you I have seen a relatively low quantity...

Since gain is effectively doubled using a differential design, noise should be a wash, or in fact just a little better since it goes by square root and gain linearly, IIRC.

In my previous life, virtually all my designs were differential, but they were not audio.

 

[NorthStar]

I don't agree with your statement one bit. Balanced audio was a solution to a very real problem in recording studios where long cable runs and hum were a real issue. If they didn't have benefits for regular audio systems, we wouldn't see them being used.

You keep touting the odd-ball gear that measures better in unbalanced mode than in balanced mode. I could be wrong, but I think these are the exceptions and not the norm as by design, the balanced gear should have better measurements. Balanced gear is typically more quiet and has more gain than single-ended circuits which is usually highly desirable. Is balanced gear more complicated? Yes. Does it have real world benefits? Yes.

But this thread ain't about Recording Studios, it's about John's own Home stereo sound system!

True, you are right about the measurements, but mainly on fully Differential Balanced products.
You know what I mean...

'Gain' has nothing to do with sound quality, or does it? ...'Typical'? What is typical in audio?
And is that good?

Just having a conversation...

 

[NorthStar]

Hmmm... If the design uses op-amps, balanced may require extra components. If discrete, the number of components should be essentially the same, and the differential (balanced) design should offer better rejection of even-order harmonics and higher CMRR/PSRR. Most of the discrete SS preamps and almost all power amps I have seen above the very cheapest use balanced circuits internally, converting at the input stage and switching back to single-ended at the output stage. That said, I admit that relative to most of you I have seen a relatively low quantity...

Since gain is effectively doubled using a differential design, noise should be a wash, or in fact just a little better since it goes by square root and gain linearly, IIRC.

In my previous life, virtually all my designs were differential, but they were not audio.

Conrad-Johnson?

 

[DonH50]

I am not sure what you mean? CJ and ARC, and probably others, have used balanced circuits in their power amps for ages; I do not know about the CJ preamps, and last I saw ARC was still single-ended intheir tube preamps. I built a custom balanced tube pre a long time ago, and in that case it did require more components. Interestingly, while it measured much better and sounder "cleaner" than the tube preamps I compared it to, most tube-friends felt it sounded too "solid-state".

 

[microstrip]

Conrad-Johnson?

Conrad-Johnson preamplfiers are just a case of simple topology with a very complex implementation.
As the simple circuit they use for gain is very sensitive to power supply quality, the power supply is very elaborated and must use high quality components. Also they are very sensitive to the mains power quality.

 

[NorthStar]

Conrad-Johnson's ET3 SE Preamplifier. ...Single-ended.

Placette Audio Active Line Stage. ...Unbalanced inputs.

Ypsilon PST-100 Mk.II ($37,000). ...XLR input and output jacks are provided, but the circuitry is Unbalanced only.

Conrad-Johnson Classic. ...

*** Not all preamps offer balanced inputs and outputs.

 

[bblue]

BALANCED is not DIFFERENTIAL

There seems to be some confusion or misunderstanding of balanced inputs and outputs.

A true balanced input (pins 2 and 3 of an xlr) rejects anything in common to those signal lines based on impedance matching, which must be carefully controlled in the cabling to be effective. In a balanced input the two signal lines do NOT have to be differential. In fact, only one of them has to contain audio if you don't want the 6db gain provided by differential signals. As long as those two signal lines are driven by an equal impedance and the cabling maintains a consistent impedance throughout its run, the balanced input will reject any signal that is in common to them, such as EMI, RF, clicks and pops, or whatever. Even the capacity of the signal lines can become moot in this scheme.

But a differential signal may not necessarily be impedance matched, or maintained along the IC run, and therefore does not have the advantage of common mode rejection at the input. Also, differential inputs may not necessarily be balanced.

Of possibly greater significance is the IC itself. A traditional balanced IC is a twisted pair inside a tight shield, as this is the easiest way to maintain a constant impedance from end to end. A so-called balanced IC that is unshielded and simply connects pin 1 to pin 1, pin 2 to pin 2 and pin 3 to pin 3 on the XLR ends, is NOT balanced. This is a worst case IC because not only is it not shielded (or is shielded in total, not just signal pins 2 and 3) its signal runs (pins 2 and 3) are not impedance maintained. Therefore at the balanced input its performance is anybodies guess. An unshielded IC with pins 2 and 3 wiring carefully impedance matched end to end MAY have pretty decent characteristics at a balanced input.

So there's a lot to consider when you argue about the merits (or not) of 'balanced' wiring.

My own take is that in all cases except simple short runs (some exceptions), true balanced differential wiring is preferred for accuracy and consistency of the signal. It also treats the + and - signal lines equally.

To me, unbalanced in general is flawed when connecting different chassis and internal chassis wiring topologies together because it treats the signal lines differently. The unbalanced 'hot' pin may be some exotic wire construction, but the other side of the signal (the return) is carried by a shield, a ground wire, or what have you, of a completely different topology. Some cables (MIT, Monster, several others) use the same conductor type for both signal lines of an unbalanced cable, and utilize a telescoping shield originating from the source but not connected at the target. That's an improvement. But in a system where there are many chassis interconnected, there can be multiple (and often different types of wire) connections which make subtle contributions to the return path (only) of all involved IC paths. I hope I'm explaining this in an understandable manner. It's a complicated issue and not easily resolved unless a system wide approach is made, which takes into account the internal grounding topologies of each piece of equipment, and how each piece is connected to power. (When using grounding power cables, there is yet another return path which becomes an influence on the audio return path). Proper balanced interconnects eliminates all of this.

--Bill

 

[NorthStar]

Bill, great post! And welcome to WBF! :b

Bob

 

[bblue]

Bill, great post! And welcome to WBF! :b

Bob

Thanks Bob. I've been lurking for awhile, soaking it all in and becoming familiar with the cast of characters!

--Bill

 

[Johnny Vinyl]

Thanks Bob. I've been lurking for awhile, soaking it all in and becoming familiar with the cast of characters!

--Bill

And we have a few!!

 

[flez007]

Not sure if this has been covered, but some power amplifier designs that have both input options (RCA or Balanced) recommend or need to short two of the three balanced plugs (via a small U jumper) if one decides to take the unbalanced route. This is the case, based in my experience, with some Pass and Levinson amps.

 

[microstrip]

There seems to be some confusion or misunderstanding of balanced inputs and outputs. (...)

--Bill

Bill,

Thanks for posting a summarizing report on the balanced versus single ended debate, but IMHO, your free use of the balanced and differential words isolated or taken out of the normal expressions "differential signalling" (transmission of signals using complementary signals) , "differential input" or "balanced audio" risks to confuse our non technical readers.

We should remember common mode rejection is not an ideal property in real world - rejects anything in common is not true - it is why we have to deal with input stage common-mode distortion

Also, you appreciation of the balanced mode versus unbalanced on terms of because it treats the signal lines differently. completely ignores the grounding concepts . its problems ans solutions in single ended mode.

I suggest our readers interested in these features go to the sources:

http://en.wikipedia.org/wiki/Balanced_audio

and

http://en.wikipedia.org/wiki/Differential_signalling

BTW, my current equipment is balanced - but I do not have any preference in this mode, I know of comparable performance systems that are single ended!

 

[NorthStar]

http://en.wikipedia.org/wiki/Balanced_audio

http://en.wikipedia.org/wiki/Differential_signalling

Thanks for those links Micro. :b

 

[bblue]

Bill,

Thanks for posting a summarizing report on the balanced versus single ended debate, but IMHO, your free use of the balanced and differential words isolated or taken out of the normal expressions "differential signalling" (transmission of signals using complementary signals) , "differential input" or "balanced audio" risks to confuse our non technical readers.

Microstrip, I was using the terms specifically to describe particular behaviors. And to point out the fact that a 'balanced audio' IC and input was a different animal from a 'differential signaling' IC and input, though a properly designed IC and input stage can (and should) be both. In the real world with the IC's and associated equipment we are offered, they are frequently not working as you'd think regardless of how those 'features' are promoted by the manufacturers, particularly in the case of IC's.

Here is a translation guide:

When I used 'differential' it means 'differential signaling' as applied to an IC or input.
When I used 'balanced' it means 'balanced audio' as applied to an IC or input.
When I used the terms together it means 'balanced audo' with 'differential signaling', as is the most frequent case.

We should remember common mode rejection is not an ideal property in real world - rejects anything in common is not true - it is why we have to deal with input stage common-mode distortion

Is there any such thing in analog audio?. With a properly designed balanced differential input stage and (twisted pair) IC the common mode rejection is significant, to 60db or greater rejection of the common mode signal.

Also, you appreciation of the balanced mode versus unbalanced on terms of because it treats the signal lines differently. completely ignores the grounding concepts . its problems ans solutions in single ended mode.

I admit this would be vague to some readers. However I did refer to power supplied to each device, and with that comes grounding, in combination with inter-chassis connections of shields or additional return lines, including AC grounds. That provides different, multiple, returns paths for a given input, and was my point.

I suggest our readers interested in these features go to the sources:

http://en.wikipedia.org/wiki/Balanced_audio

and

http://en.wikipedia.org/wiki/Differential_signalling

As do I. My post was not intended to include this much additional detail, only to point out the basics and the need to differentiate the two concepts.

BTW, my current equipment is balanced - but I do not have any preference in this mode, I know of comparable performance systems that are single ended!

There may be an occasional combination of equipment that could produce results close to a truly balanced system (there I go again, tossing incomplete terms around). The differences may be subtle, but still there. I believe you have to treat both + and - signals identically to achieve that final level of transparency, not just tie chassis together with a common ground.

Thanks for the comments.

--Bill

 

[j_n]

Of possibly greater significance is the IC itself. A traditional balanced IC is a twisted pair inside a tight shield, as this is the easiest way to maintain a constant impedance from end to end. A so-called balanced IC that is unshielded and simply connects pin 1 to pin 1, pin 2 to pin 2 and pin 3 to pin 3 on the XLR ends, is NOT balanced. This is a worst case IC because not only is it not shielded (or is shielded in total, not just signal pins 2 and 3) its signal runs (pins 2 and 3) are not impedance maintained. Therefore at the balanced input its performance is anybodies guess. An unshielded IC with pins 2 and 3 wiring carefully impedance matched end to end MAY have pretty decent characteristics at a --Bill

It is not difficult to make a twisted triad which maintans a constant impedance on all three wire combinations. For example, 100 ohms + to - and 100 ohms each to "pin 1". All one has to do is maintain insulation contact between all wires. Twisting with a drill will not do that, as the unwrap will open the spacing. Hand twisting, or machine where the spools counter-rotate can do this also.

The big problem with triad-twisted is the fact that both signal conductors with respect to the common, will have a pair centroid which is helical, wrapping around the common center of the triad. This is a slight deviation from the common centroid requirements which eliminate differential nearfield magnetic flux pickup.

Welcome to the forum Bill..I see you are no stranger to EE...

Cheers, jn

 

[bblue]

Thanks, jn. No, no stranger at all.

I don't understand what you're trying to say in this sentence: "Twisting with a drill will not do that, as the unwrap will open the spacing. Hand twisting, or machine where the spools counter-rotate can do this also."

Also, I believe you would need to be concerned with not only the impedance between + and pin 1, - and pin 1, bit also between + and -. Could a triad even be done that would accomplish that? Maybe an over/under braiding, but I'm not sure that would net out to the same thing.

--Bill