Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Here is a simple description of how a balanced audio signal works.

A new difference

We make friends by focusing on our common experiences, thoughts, opinions, and tastes. If our differences are too great, we typically don’t bond. The opposite is true with a difference amplifier, the heart of most electronics you listen to.

We’ve looked at balanced inputs and cables to discover how balanced audio ignores common noise and amplifies only differences. Now, let’s look at a balanced amplifier itself.

A balanced amplifier is more properly called a difference amplifier. Both terms are accurate. Differential amplifiers are balanced, and balanced amplifiers are differential. But I prefer to think of this type of circuit as a difference amplifier because it more accurately describes how it does it, rather than what it does.

Difference amplifiers are based upon this circuit, called a differential pair (diff pair for short).

It looks complicated but it’s not. Q1 and Q2 are the pair in diff pair. What’s drawn are regular transistors, though they could be FETs or vacuum tubes. What they are doesn’t matter. It’s how they are connected that does.

V+in is where the + of a balanced cable would go, V-in is where the second, out of phase, input from the cable goes (Remember? There are two signal wires in a balanced cable).

Ignore all the rest of the squiggles and notes.

Focus instead on where Q1 and Q2 are connected directly together—the two arrows are pointing at this junction. See it?

For purposes of our understanding, this connection of the two transistors is all we’re interested in.

Whatever signal is placed on either of the two inputs, an identical copy comes out where the respective arrow is (called the emitter).

If the two emitters have the same signal (because the inputs have the same signal), there is no difference between the two, thus, no current flows. Like a teeter totter with two equal weight people, or closer to home, our example of the two wires of a lightbulb placed on the + terminal of a battery. Nothing flows, because there are no differences.

However—and of course you saw this coming—place opposite signals (out of phase: one rising as the other is falling) in the diff pair’s inputs, and current flows.

 

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Paul is continuing his take on balanced audio signals and draws a comparison here with other items of trivia. Who knew?

 

Pop quiz

What do airplane wings, teeter totters, balancing scales, subtraction, gravel sorters, batteries, stereophonic sound, and balanced audio have in common?

They all rely on differences.

  • Airplane wings can lift tonnage by the differences in air pressure between the top and bottom surface.
  • Put two equal weight people on a teeter totter and nothing happens.
  • Place two identical objects on a balance beam scale, even if they are massive, and you get nothing.
  • 6-6=0.
  • Pea gravel doesn’t come naturally—only rocks having a common size are sorted through an appropriate filter.
  • Attach two wires of a lightbulb to the + terminal of a battery, you get nothing—moved to the opposite pole, light.
  • We create the phantom third channel of stereophonic sound from elements common to left and right—differences are filtered out of the center.

I am sure there are many more examples of difference amplifiers and common element sorting filters.

You can begin to grasp how a difference amplifier, responsible for eliminating common noise in cables, separates one from the other.

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

More balanced vs unbalanced audio from Paul.

Ins and outs

I think one of the problems people face understanding balanced audio has to do with how it is applied. The terms that get thrown around, like true balanced, are so generalized they lose meaning. They get inaccurately applied across the board.

In tomorrow’s post I will show you how a balanced signal works and why. But for today, I wanted to focus on the broader scope of application.

Let’s assume there are three main points in a circuit where balanced audio can be applied. The input, the middle, the output. These three generalized areas where the term balanced can apply, are all very different and need to be separated if we’re to achieve any sort of clarity of understanding.

Balanced input

This is the most most common application of balanced audio. Any properly designed amplifier featuring an XLR balanced input is often said to be a balanced amplifier. This is misleading and does not mean what you might think. Just because an amplifier sports an XLR connector doesn’t mean it is a balanced amplifier. All it means is that it has, as its name implies, a balanced input. The distinction is an important one.

A balanced input has the advantage of lowering incoming noise from the connecting cable. Noises picked up by the connected cable are reduced in the balanced input, through a process called Common Mode Rejection, a subject we shall delve into tomorrow.

For the sake of brevity let me suggest simply that a balanced input’s advantage is confined to reducing noise from the connecting cable. It is not a balanced amplifier, not does it enjoy the advantages of a balanced amplifier. It is, simply put, exactly what its name implies.

Balanced amplifier

Strictly speaking, a balanced amplifier does not necessarily have a balanced input or output. It usually does have both, but as in point number one, the term’s accuracy does not demand it, nor does every design benefit from it.

There are numerous schemes to build a balanced amplifier. The most common is a series of differential pairs, a design we use a lot, and one I will detail in the coming days.

An amplifier qualifying as balanced is said to have two identical signal paths, each handling a signal out of phase with the other. I would argue this is not what we mean when we think of balanced audio. Instead, a better description would include one additional requirement. Common Mode Rejection—the benefits of which are huge—including lower distortion and noise.

To be a balanced amplifier in my book means to be a differential amplifier—an amplifier that internally amplifies only differences, ignoring anything in common.

More to explain later.

Balanced output

This is very common that amplifiers have balanced outputs. Any design, whether single ended or balanced, can have balanced outputs.

An amplifier sporting an XLR connector at its output, presenting two signals, each out of phase with the other, can be said to have a balanced output. This is the simplest form of balanced for design engineers to achieve and provides zero benefit to the device that has it.

The only benefit of a balanced output is to be found later, when connected to a balanced input.

 

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Happy Thanksgiving, everybody.

Togetherness

I want to take this opportunity to thank each and every one of you for your kindness and community I so enjoy.

It’s been five years—six this August, that I have been allowed to write these posts every day. What a privilege to have written more than 2,000 columns, sharing with readers the many stories, experiences, laughs, trials, tribulations, elations, and failures. The humanness of it all.

Together we share a common bond. Music, hifi and friendship.

I just wanted to say thanks and trust that you spend a good day with your family and loved ones. Even if your country doesn’t set aside this day to give thanks, it’s always good to take a breath of sweet air and remember life is a journey, one that can end in the blink of an eye or go on for an eternity.

They say “life is short” but in fact, it’s actually a lifetime.

You and I are all we have on this earth. Thanks for being there.

 

 

 

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Promoting dischord

Balanced audio isn’t very friendly. While most in society strive for harmony and agreement, the basics of balanced audio call for the exact opposite: a complete rejection of anything in common. But peace and harmony aren’t what we want when we turn to a balanced approach to signal handling.

We’re going to start our understanding of balanced audio by first separating tasks. This is important because the term balanced audio has so many applications. For example, there are balanced outputs, balanced amplifiers, quasi-balanced, fully balanced, and balanced inputs. It is this last category we’ll start with.

A single ended (SE) cable has only two conductors: one for the signal, the second for ground. Most are shielded, which means the ground conductor wraps around the outside, surrounding the inside signal wire, and is called the “shield”.

Attach an RCA connector on each end and you have a single ended cable. Construction varies immensely (this is high-end audio, after all), but at its core this is what a single ended cable is all about. Two wires, each isolated from the other, one acting as an outer “shield”.

A balanced cable is the same but with one addition. Instead of the SE’s single wire in the center, a balanced cable has two, each with insulation so they don’t electrically touch.

Going back to the SE cable, we understand the outer ground conductor (the shield) has an important role to play. Noise reduction. Think of this shield as a protective outer coat from nasties: cell phone signals, static, electrical garbage floating about. These unwanted electrical vermin never get past the outer shield and thus lower noise as they are swept away to the system’s ground. The incoming amplifier now gets a relatively clean signal from which to amplify.

This is all nice and tidy until you look closer. Not all noise is the same, and some types are like deadly viruses worming through to infect both the shield and the signal conductor.

That’s where a balanced cable comes to the rescue.

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

This is Paul writing about balanced audio. PS Audio’s DSD DAC, BHK preamplifier and BHK amplifiers all use transformers to turn single ended into a balanced audio signal and I like it.

The nicer AV Processors for Home Theaters from Marantz have balaced inputs and outputs!!

 

Overnight success

It takes about ten years of hard work to become an overnight success. In the case of balanced audio, it took many more than ten.

Balanced audio has been around as long as there have been audio transformers in use—and that’s a long, long time.

I thought it would be a good idea to revisit the subject of balanced audio and we’ll start with common myths.

Common myths

Boy, we Audiophiles sure have a lot of myths. Right? Everything from conspiracies to misunderstandings becoming fact. Let’s look at just a few of the Audiophile myths concerning balanced audio.

  • It takes twice the circuitry to make a balanced input
  • If you feed a balanced amplifier a single ended signal it defeats its balanced benefits
  • Only a handful of devices actually enjoy the benefits of a balanced input, the majority are fakes
  • Single ended circuits sound better because they are simpler

Twice the circuitry

This first one is pure bunk in the most practical sense. A balanced input can be designed with a single op amp, or a single tube, or a simple diff pair. Yes, in its dumbest form one could accurately suggest that you cannot make a balanced input with but one transistor – but then you cannot make any form of good sounding amplifier with but one transistor – so the argument is nonsensical.

Only balanced signals get balanced treatment

This is true for the input to an amplifier, but false everywhere else. A properly designed balanced amplifier takes single ended or balanced signals in and they become balanced for the rest of their journey. The simplest example of this is an audio transformer. Regardless of its input, balanced or single ended, its output is always balanced. Same with a purpose designed tube, or diff pair. It is true most designers don’t follow through with balanced designs, but that is their choice, not a limitation of the art.

Most XLR inputs are fake

Bullshit. It is true that there are some in the world of cheap amplification devices, even some pro applications offering “courtesy” XLR ins without purpose, but the vast majority of high end audio equipment offering XLR inputs are balanced. Where this myth started I can only guess. For years there were those companies in our industry that claimed to be balanced amplifiers when all they did was flip the output phase at the last moment. But when we look strictly at inputs where balanced biggest benefits are to be enjoyed, I’ve never seen a high end audio company that played such games.

Single ended sounds better because it’s simpler

Give me a break. Properly designed, it is neither simpler nor better. I won’t get into a pissing match over designs—single ended vs. balanced—because there are simply too many variables to contend with. But the notion that simpler is better, while true, does not here apply in the strictest sense of its meaning.

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Paul’s post today talks about balanced audio, where components are designed to be connected with XLR, three prong connectors, as opposed to the usual single prong RCA connectors, we are used to using.  XLR’s connection is the way professional audio goes and there are good reasons for this.

Many in high end audio think it’s a waste to design this way, as its more complicated and expensive. After many years of both, I’ve gravitated to a fully balanced system. Seems pretty obvious that I believe in this, although it is more expensive to implement and not as big a deal in high end audio, where cable runs are much shorter in length than professional systems.

A component has to be designed balanced and Paul talks about this, as there is more than one way to skin that cat……so to speak…

Truth or fiction?

If you approach a piece of equipment with balanced inputs your expectation seems obvious. To enjoy balanced audio’s benefits, of which there are many.

You would rightly feel cheated if that balanced input wasn’t actually doing anything differently than its single ended mate. Right? Such is the buyer’s dilemma.

Not all XLR inputs are balanced. And this is particularly true of some lower cost products that accommodate the different connector without offering the assumed benefits.

In fact, there’s even an unfortunate term in the Audiophile’s lexicon to weed out the fictitious inputs from the truthful ones. True balanced.

I cringe every time I write “true balanced”. The same logic of presenting something as real when it is not applies to cheese food, a term forced upon processed food manufacturers presenting their chemical brews as cheese—a word with specific meaning. Providing a single ended XLR receptacle without notice is just as misleading as calling (Canola Oil, Maltodextrin, Milk Protein Concentrate, Sodium Phosphate,Lactic Acid, Whey Protein Concentrate, Mustard Flour, Worcestershire Sauce, Sodium Alginate, Sorbic Acid and food coloring) cheese.

Though I’ve covered this subject before in these posts, perhaps it’s time to review once again what it means to be balanced. What does that actually mean, and what are the benefits of balanced audio when properly applied?

Stay tuned.

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Today’s audiophile internet post covered a room at RMAF that just did audio streaming, without a CD player or turntable. Their point was that a purposefully build streaming component, streaming Roon, can sound very good and apparently, it did.

The system listed out at $17,329 for a source component, amplifier and loudspeakers. It did not include Cardas cables, which probably added a couple thousand to the total.

I guess I’m getting de-sensitized to the cost of audio components a bit, as this now sounds like a reasonable sum to me. Still, I can put together a very good musical system for a lot lees and I enjoy doing this.

Now from Paul about balanced circuits.

I completed my balanced signal chain on Friday with a balanced preamplifier, called the BHK Preamp, from PS Audio and totally agree with Paul about this. The BHK stands for Bascom H. King, who did most of the design work on the preamp and is a very good engineer and writer, besides apparently being a fine fellow all the way around..

Previously, I had been using a Rogue Audio RP-5 single ended preamp with balanced adapters and basically, while sounding excellent, it was a choking point in my system as its available gain was cut in half because of the way I was using it. The preamp, made in America, was excellent, but it didn’t match well to my all balanced system. I knew this and basically bought it to support a US manufacturer, but while waiting for a balanced version of it to come to market, I decided to buy another American made product and it is stupendous.

No more single ended for me ever again!!

Maintaining balance

There was a time when almost no high-end audio equipment had balanced inputs. Today, the opposite is true.

The same cannot be said about pro audio equipment, where balanced ins and outs have been the standard for as long as I can remember. The reason pros adopted balanced is easy. Noise reduction. I don’t imagine the same can be said for high-end audio, so, why the switch?

I wish I had a ready answer. PS Audio started adding balanced inputs on our power amplifiers in the early 1990s because a few customers with balanced preamps demanded it. Once added to our power amps we felt obligated to add them to our preamps as well—if for no other reason than to answer the inevitable question of why one and not the other. This same logic cascaded to the sources and soon everything was both balanced and single ended.

Though we manufactured balanced input/output equipment I didn’t use balanced until much later. My collection of hand picked expensive interconnects were all single ended and I was hard pressed to invest again.

Now the tables are turned. I have only a smattering of token single ended cables and everything in the system is balanced.

They just sound better.

Sometimes we fall into or out of balance merely by circumstance.

In this case, my system’s the better for it.

.

 

 

 

 

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Paul talking about PS Audios new power amplifier, Stellar.

Words

We use words to describe that which we feel, see, hear, and imagine. Inadequate at best, commonly misleading, words struggle to convey meaning.

I had suggested in my post of a few days ago that our engineering team was able to “neutralize” the problems common to class D output stages in anticipation of connecting a robust Analog Cell from which to direct our upcoming affordable amplifier’s sonic flavoring.

Based on the comments I received my use of the word neutral did not properly convey my meaning. Perhaps a better word might have been “sterile” though I did not employ its use because of the childless, bacteria free, image it brings into my own mind.

How then are we to accurately communicate meaning when it comes to getting out the thoughts lodged in our heads?

Last night we cranked Stellar up with one of my references, John Rutter’s Requiem as sung by the Turtle Creek Choral’s 225 voice ensemble, replete with pipe organ—as tough and complex a challenge for electronics as can be found. It soared without a hiccup.

Auditioned in a vacuum (without comparison to the BHK) I could find no fault. How then to explain such an observation in a few words without being miselading? In fact, I don’t know.

When I tell the story of my experience readers hopefully build their own mental version of it—as if they too had been enjoying the waves of sound washing over them—when in fact no one can truly share the same experience.

Words escape me time and again.

“Any word you have to hunt for in a thesaurus is the wrong word. There are no exceptions to this rule.”
― Stephen King

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Painting pictures

Authors paint pictures with words, composers with notes, musicians with sound.

Watching the terrific PBS series Soundbreaking last night I was inspired by the late George Martin’s words as he described how once, producers made every effort to perfectly photograph sound. Thanks to his own ground breaking innovations with the Beatles, first heard on their album Revolver in Lennon’s Tomorrow never knows, all that changed.

Tape loops, backwards playing concoctions, sped up, sped down, the Fab Four and Martin started painting with sound, as he describes it. Less photo realistic, more impressionistic.

What was fascinating to me was his depiction of working a lifetime at perfecting an exacting replica of sound—a practice near and dear to the hearts of Audiophiles—and moving towards sonic brush strokes without reference to reality.

We’ve come to accept the tricks and manipulations of the recording studio as part of recorded music and we ask our systems to deliver a “photographically perfect” reproduction of it, even if it isn’t itself real.

As Audiophiles we demand clear and unobstructed views of the recorded arts, regardless of the creator’s intent on realism.