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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.

The free lunch counter

In yesterday’s post, we learned that to effectively lower impedance we need to add energy.

That’s what a power amplifier does and what a passive power conditioner cannot do.

In fact, a passive power conditioner (one without an active power amplifier inside) makes things worse. It raises impedance.

Wrong direction.

To get the most out of our stereo systems we need to figure out a way to stop restricting the power they need by actively lowering impedance.

Good things come at a price.

If we want to lower impedance we either move our home next to the power generating facility or add an amplifier to actively lower impedance.

Here’s why.

The average home wiring chain presents an impedance of between 1Ω and 0.5Ω depending on the wire gauge within the home and the distance from the utility pole.

14 gauge wire, which is the standard our homes are wired with, has a resistance of about 2.5Ω per 1,000 feet. The thicker wire feeding our homes has about 10X less resistance. So, we’re going to assume a combination that gets us to an average of about 1Ω.

1Ω is a lot of resistance for our power to have to struggle its way through. As our main power amplifier tries to drive those 4Ω (or lower) speakers, it’s struggling to suck needed power through a restrictive 1Ω pipe.

What happens if we add an impedance lowering amplifier between the high impedance power line and our musical power amp?

Voila! Now, instead of 1Ω of restricted access to power, our musical amp can enjoy 100, or even 1,000 times lower impedance feeding it.

Our story continues tomorrow.

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.

Shortening wire length

In yesterday’s post, we posed the question of what might happen if we were to lower or even eliminate the impedance inherent in the AC power wires feeding our home.

The answer is simple. Dramatically better sound.

Something we all want!

But, how best to eliminate or significantly lower the impedance of hundreds (often thousands) of feet of connecting power cables shared by our neighbors?

Traditionally, lowering impedance inherent in wire can be handled in two ways: shortening its length and/or increasing its thickness.

Increasing wire thickness from the standard of 14 gauge copper, which is about 0.06″ thick, to something ridiculously heavier like 0 gauge wire, which is nearly ten times the thickness (times 3 conductors), would help but wouldn’t solve it. Only thickening and shortening the wire to mere feet would get the total impedance where we would want it, to perhaps 0.01Ω or lower.

The problems with taking these steps would be one of practicality (or the lack thereof). Let’s start with thickening the wire. 3-conductor 0 gauge wire is about 1.5″ thick and weighs in at about 1.5 lbs per foot. That’s going to be a bear to install in the walls (never mind the impracticality of typing that wire into an AC receptacle). But, let’s say we managed all that copper. We still need to shorten it to mere feet. To do that we’d have to move our home next to a noisy, stinky, coal-fired power generating station.

We might get some spousal pushback.

Fortunately, there is an alternative. A power amplifier.

Let’s back up a moment.

If you want to power a pair of loudspeakers you won’t get very far connecting the output of your preamplifier to them. Preamps can’t drive speakers because their output impedance is too high.

To lower a preamplifiers output impedance you need to add energy, something a power amplifier is very good at.

Power amplifiers have high input impedance and low output impedance.

Does this sound like something that might interest us in our quest to reduce the impedance of the power line from high to low?

Methinks, maybe.

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.

For phono stages and preamps, external power supplies are almost always best. I recently replaced a high quality wall wart power supply for my Dynavector P75 Mk4 phono stage, with a large, well regulated external supply, which sends DC to the phono stage electronics themselves and was able to squeeze even a little more quietness from my Well Tempered Labs turntable rig.

External cures

From as early as 1980 it had been clear to us that the bigger the power transformer the better the sound—a fact that at first didn’t make a whole lot of sense.

Why would a preamplifier that consumed no more than a few watts benefit from a power transformer capable of 100 times that?

Impedance.

Turns out that because bigger power transformers have thicker wire they have lower impedance, thus less modulation.

An easy way of visualizing the difference between high and low impedance transformers would be something akin to spongy vs. brick wall. A spongy power transformer is malleable by the load—or in our case, modulated by the music. A bigger transformer is less affected and thus is impervious to being pushed around by the amplifier’s circuit.

Once we recognized the importance of the power transformer we began implementing bigger and bigger ones until they no longer fit into the chassis, prompting us to begin offering external add-on transformers. Here’s one of the first we ever produced:

While we as the designers and manufacturers of our products could choose any size transformer we wished, that certainly wasn’t the case for others who had already made their choices and now their products were out in the marketplace.

This brings us back to the problem I was facing in the late 1990s when I hoped to come up with a way of improving power supply performance of products not our own.

Would it be possible to externally increase the size of an internal power transformer? And if we could, how about those power supply capacitors inside? Any chance of adding more capacitors without opening the case?

Seemed at the time like more of a fairy tale than possible, but…

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.

Miracle cures

While standing in the supermarket checkout line I couldn’t help but notice the splashy magazine headline.

“Lose 13″ off your waist in 1 week”.

The only way in 1 week to lose 13 inches off your waist is through surgery, something the magazine editors were not promoting.

Most all of us are in one way or another searching for a miracle. Perhaps it’s the external power supply that will change everything, or that one cable that will forever bring life to the system.

Certainly, there can be miracle products and it’s good to keep a watchful eye open.

In my experience, it’s more likely that a miraculous sounding stereo system is the result of hard work and good decisions.

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.

Amateur Audiophiles

One of the reasons I wrote The Audiophile’s Guide was to help fix the biggest problem in high-end audio systems. The one most of us take for granted, yet never master.

Setup.

Sure, we all know the basics: approximately where to place the loudspeakers, how to connect the kit, how to tame a lousy room.

But basics are not mastery in the same way learning how to boil water doesn’t make you a culinary expert.

With over 10,000 copies in circulation, I am happy to report that more systems sound better than ever before.

But, the Guide doesn’t work for everyone because not everyone gets the same benefits from simply reading a book.

That’s where someone like David Snyder can help. David, who refers to himself as an amateur audiophile (aren’t most of us?), has taken apart every aspect of The Audiophile’s Guide and methodically laid it out in much easier to understand language than I was able to.

He’s published this work in a 5-part series called Unlocking Great Sound and to be honest, he’s done a far better job than I.

If you’re interested, you can go here and begin with part 1.

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.

Systems

Each of us produces a liter of mucus per day. Snot, actually, and we use it to keep our esophageal system working smoothly. And here’s the thing, despite the fact that’s a lot of snot, unless there’s a problem we never notice it.

And that’s the way most systems work, seamlessly and in the background until something goes wrong or we yearn to make something better.

It’s the fringes we notice, not the main system.

It is good and proper we focus our time and energy getting our core audio systems functioning properly, but it’s almost never what we think about.

I have for many years been a proponent of stepping back from the pieces in my system I interact with like the transport, preamplifier, or streaming interface, and pay homage to my silent partners that make it all happen: the AC power, amplifier, audio cables, and rack system.

Central systems are easy to ignore until something goes wrong or we wake up to the fact we can make improvements that matter.

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.

Armchair quarterbacks

The classic armchair quarterback can be a valued member of any team. Their dispassionate views often add value to those actually making the plays.

But making the plays, designing the audio equipment, making the tough decisions of how to get from point A to point B is a very different challenge than what a critic faces.

What designers, engineers, and craftspeople bring to the table is hands-on experience—the hard-won skills to successfully bring a new product or service from an idea to a finished piece.

When I share my knowledge and experience of designing and building products with the HiFi Family it comes from a desire to help others see what I see without their having to spend 50 years accumulating it.

I truly love the role reviewers, critics, and armchair quarterbacks play. They are not mired in the detritus of sorting through the years of successes and failures.

I do wonder sometimes if they’ve forgotten the differences between passing judgment and actually envisioning, designing, building, and producing that which they judge.

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.

Hope for the future

There are many reasons why we launched Octave Records, but chief among them was to add to the small supply of high-resolution recordings as well as to help set standards of what we as the high-end audio community demand in the way of well-recorded material. To that end, I think we’re on the right track.

Part of the reason we felt compelled to add our voice into what seems like an empty wilderness is the deplorable state of most modern recordings. Seems the state of the art has been sliding backwards for years.

I was heartened to learn that a committee formed by the Grammys has been pushing to set some standards for high-resolution recordings. Though they are not taking a stance on either heavy-handed compression or the loudness wars, they are at least addressing the issue of resolution and…get this…pushing hard against not only MP3, but raising the sample rate above CD quality!

Imagine!

“THE REAL DIFFERENCE BETWEEN 44.1/16, 48/24, 96/24, 192/24 AND BEYOND
Is there truly a noticeable difference between MP3s and 192/24 files? Absolutely, but everyone owes it to themselves to listen and compare. In most cases the differences between CD-quality and 192/24 are at least noticeable, and frequently, they are stark. Skillfully mixed and mastered music with a wide dynamic range benefits dramatically from a hi-res workflow. For recordings
such as symphonic film scores, classical music, or other recordings that feature acoustic instruments, hi-res audio is a perfect fit—the increased audio quality can be appreciated by virtually anyone who hears it. In the experience of this committee and the audio professionals we interviewed (including numerous rock, pop, and urban producers and engineers whose work is aggressive and powerful), recording, mixing, and mastering at resolutions 96/24 or better results in a final product that is both sonically superior and faithful to the sound of the final mastered mix.”

You can download the paper here.

I realize this is a task akin to steering the Titanic away from danger, but we gotta start somewhere and I am heartened to read that recording engineers are being told resolutions higher than 44.1kHz are audible and preferred.

Maybe there’s hope for the future.

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.

Direction matters

Direction matters in at least diodes, capacitors, one-way streets, and game plans, but it is to the last on this list we write about today.

Being the impatient type I fully understand the temptation to jump into the deep end of a problem without a plan, but, as someone that’s been on the planet for more time than many, I also appreciate the value of a good game plan.

For example, when it comes time to choosing that new pair of loudspeakers or a new set of electronics, how many of us have clear objectives in mind?

I suspect most of our goals are more emotional than logical. I know in my case lust often outweighs reason.

If I were to offer any advice I think it might break down to two very simple questions:

  1. What is lacking in what I have?
  2. What am I hoping the outcome of my new purchase will be?

It might sound super simplistic but you’d be surprised how often these two questions go unanswered or, worse, unasked.

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.

Last but not least

Following the past few day’s posts about audio amplifier efficiency, Class AB biasing, and Class A biasing, let’s wrap our little mini-series up with another topology most of us have not heard of, adaptive biasing.

The promise of adaptive biasing is a best of both worlds scenario: the efficiency of a Class AB circuit with the performance of a Class A amp. Sounds too good to be true, right?

The first time I ever heard about an adaptive biasing scheme was way back in the dark ages, the late 1970s. My very dear friend and one of the all-time good guys of audio, Nelson Pass, then of Threshold Corporation, had introduced the idea of what we called a sliding bias scheme, part of what later became known as the Stasis Circuit used in Nakamichi, Threshold and if memory serves correctly, even the Mark Levinson No. 33.

The core of this circuitry is covered in Nelson’s patent from 1975 titled Active bias circuit for operating push-pull amplifiers in class A mode.

Simply put, Nelson’s design raises the level of Class A bias in cadence with the rising input signal.

Recall in our discussion of Class AB design that a small amount of always-on power keeps small signals always on. In other words, we apply Class A (always-on) bias to the first 10% of the amplifiers output signal level, then switch over to the more efficient Class B for higher signals. Compare that to Class A operation which is always-on for any level of signal—always generating a shit-ton worth of heat (recall Class A amps are at their coolest when at full signal out).

What Nelson cleverly suggested was this. Take what we do in an AB amp where the first 10% of the signal is Class A and actively monitor the signal level. When any given input signal starts to exceed our 10% Class A bias, raise the limit from 10% to, say, 20% (or whatever is greater than the signal level), and continue on the path all the way up to 100%. Then back down again tracking the signal. The heat-producing bias is only enough to accommodate the signal, then goes away when it’s not needed.

Thus, we get the benefits of both worlds. Efficient, and sweet-sounding.

Why doesn’t every amp use this even today? (Nelson’s patents ran their course years ago). Well, as with any design there are problems as well as advantages and this post is long enough already. Ain’t nuthin’ perfect. (We used this for several models of amps though their model numbers and dates escape me).

In any case, a juicy piece of history I’d thought I would share.

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