Category Archives: Blog Posts

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

Processes

As one whose direction is steered with his engineer’s nerd brain, I am continuously fascinated by processes.

For example, what kind of process do nut manufacturers employ to individually open pistachio shells? Haven’t you ever wondered? Is it the roasting process? Automated insertion of a hypodermic with compressed air and blowing them open?

Somehow, 95% of pistachios are opened just enough to get a fingernail inside and open ‘er up.

The answers to questions of process are often complex and hard to understand, like building a CRISPR. More often than not, they turn out to be simpler than we had imagined.

The process of designing and launching a new audio product ranges from a straightforward path of simple napkin sketches to market in a matter of months, to years-long R and D, design, testing and manufacturing.

From a customer-facing standpoint, it likely doesn’t matter much. The product is what you want and performs the way you hope and expect or it doesn’t.

While all that’s true, let us not ignore the process of selection and evaluation before making our final choice.

The processes each and every one of us go through from deciding what’s for dinner tonight to which pair of speakers sounds better than another, is not to be trifled with.

Life itself is a series of choices we make based on the processes that have over a lifetime proven to work.

*(Pistachios, it turns out, pop open naturally. All the nut manufacturers have to do is pick them when they’re mature).

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

Nyquist

Swedish electronic engineer Harry Nyquist figured something interesting out. If you want to capture sound using digital audio conversion, you need to sample at twice the frequency you hope to preserve.

Thus, if your goal is to capture without loss frequencies as high as 20kHz, you need to build a stereo system that gathers twice that frequency—40kHz. Add to that requirement the fact such a system gets wigged out if you feed it frequencies higher than the maximum sample rate, one is required to make sure a steep filter is applied before conversion from analog to digital.

Which is how we wound up with CD’s sampling rate of 44.1kHz. We need the 40kHz part to keep Harry Nyquist happy, and the extra 4kHz bit to keep engineers tasked with building a brick wall filter from jumping out of windows.

But here’s the thing. If Nyquist was correct (and he was) that we can capture with perfection half the frequency of our sample rate, why do we need higher sample rates?

After all, we can’t hear anything above 20kHz (and most of us can’t hear that high).

The answer lies not with Mr. Nyquist, but instead with the challenge of steep low pass filters. As my friend Robb Hendrickson puts it: “Whether you’re recording at 44.1 or 48kHz, you are LITERALLY applying a low-pass filter to NATURE!!!”

Indeed, it’s not the lack of 20kHz (because there is no lack of it), but the effects of filtering we hear.

If we need to apply a low pass filter to nature, it had best be really, really, high. Like 100kHz to 200kHz.

Harry gave us only half an answer. The other half is figured out by our ears.

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

I use vintage Urei 539 EQ’s, which are all analog and they sound great. So, while I get what Paul is saying, there are exceptions, like the Urei 539!

Conflating D and A

In yesterday’s post on tone controls, there were a number of comments about the use of DSP, yet few about the differences between analog and digital controls.

There is no question that if one is happy staying entirely in the digital domain, DSP EQ and correction is a near-perfect solution. We can design extensive tone controls that have zero phase shift and are sonically neutral.

The same cannot be said for analog. And therein lies the rub.

If you’re going to add tone or EQ controls to an analog preamplifier you are going to suffer added circuitry, phase shift, and sonic degradation. That’s just the cost of doing business in the analog domain.

As a manufacturer, we have to be sensitive to all our customer’s needs. We can’t, for example, produce an honest analog-based preamplifier with DSP for EQ. To do that would require the analog signal to first be converted to digital and then back into analog.

Which is why blanket statements about EQ and tone controls are difficult. We first need to set the ground rules of the playground before making blanket statements.

Just sayin’.

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

There is something to be said for tone controls, but they need to be done correctly, or they will make a sonic impact on the music. My Luxman 590 AX II has them for bass and treble and they are done very well. It even has a loudness control to be used at low listening levels, boosting bass and high frequencies. Very transparent, but when I’m using the Luxman, I listen direct as my system doesn’t much need tone controls and I almost never listen at low levels.

Tone control

There was a time in our HiFi history that the ability to electronically control music’s tone was necessary. Necessary because the entire chain of electronics and loudspeakers were bad enough to warrant their intrusion.

Sure, many bemoan the lack of bass and treble controls, even full band graphic equalizers, but for the most part, we neither miss them nor need them.

And that’s the point. Our equipment’s gotten so much better as to obviate the need for tone controls.

The crutches of the past don’t apply to the equipment of today.

Yet fond memories of their power linger on.

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

Cool history lesson from Paul.

Hertz

I can’t begin to count the number of times I’ve written the abbreviation, Hz—1 kHz, 1,000 kHz.

It is, of course, short for Hertz.

The car company?

Heinrich Rudolf Hertz was a German physicist who first proved the existence of electromagnetic waves. Invisible forces that had a specific periodicity (frequency) that later were named in his honor.

Invisible waves were first proposed by a Scottish fellow, James Clerk Maxwell (no, not the hammer murderer Maxwell Edison) who first connected the idea that three forms of energy—electrical, magnetic, and light—were all related to each other. To make it even more interesting, they all seemed to travel at the same speed (the speed of light) and they all acted in the same way (like waves). He summed these conclusions up mathematically in what later became known as Maxwell’s equations.

It was our friend Hertz (no, not the owner of Hertz Drive-Ur-Self System), who would not only prove that which no one had yet shown, that electricity and magnetism could travel through space as waves (like visible light). It was easy for people to wrap their heads around the idea of light traveling through space because we could see it. But invisible electricity or magnetism? These were spooky, invisible, phenomena.

Hertz not only proved Maxwell’s Equations were correct, but in so doing, he also invented the first radio transmitter.

“Hertz’s first radio transmitter: a capacitance loaded dipole resonator consisting of a pair of one-meter copper wires with a 7.5 mm spark gap between them, ending in 30 cm zinc spheres. When an induction coil applied a high voltage between the two sides, sparks across the spark gap created standing waves of radio frequency current in the wires, which radiated radio waves. The frequency of the waves was roughly 50 MHz, about that used in modern television transmitters.”

Unfortunately, Hertz suffered from massive migraines and in 1894 died at the young age of 36 after complications in surgery to fix his condition.

Seems medical science was considerably farther behind than physics.

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

Too many “weeds” here from Paul, but interesting to some.

Sample rates

There sure is a lot of confusion over sample rates. We hear about CD-quality sample rates at 44.1kHz (and its multiples), or another common sample rate, 48kHz (and its multiples), and then there are multiple higher sample rates (176kHz, 192kHz as examples) and of course DSD.

Lots of numbers. All very confusing.

Perhaps a short primer would help.

First, what is a sample rate? Simply put, it’s a snapshot of the audio signal. A slice of time where we capture the voltage level of the music signal. The number of times per second we take that snapshot determines the sample rate. (Bit depth determines the loudness range we can capture within each sample)

First, what’s the difference between 44.1kHz and 48kHz and why do the two exist? The former is what Sony/Philips set as a standard for the Compact disc. When we do higher sample rate versions of this standard we get 88.2kHz, 176kHz and so forth. The latter, 48kHz, is the standard the “pros” use (because, well, they can’t use something as conventional as consumers, now can they?). 48kHz gives us multiples we’re familiar with like 96kHz, and 192kHz.

What’s painful about the above two standards is the difficulty moving between them. When recording studios record at “pro” sample rates of 48kHz they then have to interpolate down a few Hz to 44.1kHz to make something we poor consumers can listen to.

Silliness.

When we nerds talk about sample rates we use different terminology. We base our discussion on how many multiples of the base frequency (44.1kHz) are in play. So, for instance, the CD sample rate is referred to as 1fs. Its multiples are 2fs, 3fs, etc.

The sampling frequency or sampling rate, fs, is the average number of samples obtained in one second (samples per second). Think of 1fs as the minimum baseline to capture 20Hz to 20kHz.

While we might be familiar with all the differing PCM sample rates, DSD brings in a whole other dimension with its far higher sample rates. For example, standard DSD is 64fs while double rate DSD is twice that at 128fs. So what’s that mean? Well, 1fs is running at 44,000 times per second, while 64fs is running at 64 times that frequency, or 2,822,400 times per second! That’s fast, man.

And, while DSD is so much higher of a sample rate as to raise a few eyebrows, it’s instructive to remember it’s a 1-bit system compared to a basic 16-bit system like PCM (remember that the number of bits is needed to measure amplitude). This boils down to something less hair raising if we do a bit of math. 64fs (1xDSD) runs at a very high clock rate of 2,822,400 Hz (2.8mHz). Now, simply divide that by 16 (the number of bits in a PCM word) and guess what you get? A sample rate of 176kHz. Sound familiar? 176kHz is the same as 4fs PCM. So, while PCM requires 16 bits to adequately measure amplitude, and DSD needs 16 single bits to do the same, it all kind of works out in the end. (Don’t take what I just wrote about DSD and 16 bits as literal. I use it only as a means of helping form a picture. DSD is far more complicated, using a Sigma-Delta Modulator, noise shaping, etc.)

Without getting too much more in the weeds, that’ll give you a brief simplistic overview of sampling rates.

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

Loudspeakers designed and measured to sound flat in an anechoic chamber will sound terrible in a real life listening room environment. That’s just the way it is.

The price of flat

There’s really no such thing as a flat loudspeaker.

Loudspeakers are such inaccurate mechanical devices that if one were to attempt a flat frequency response, enormous levels of compensation would need to be applied. And, even then, those compensating changes in amplitude would only work in a very small area.

Unlike an audio amplifier whose input vs. output is fairly straightforward, speakers present an enormous challenge—one that depends on so many outside variables (box, baffle, room size) as to make it a non-starter.

The price of flat, as it pertains to loudspeakers, is equivalent to the price of peace.

Unaffordable.

Not to despair. Fortunately, our ear/brain mechanisms are powerful enough to adjust so that when we listen, it sounds “flat”.

And at the proverbial end of the day, if it sounds flat then it is flat.

Problem solved.

 

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

Decaf

The taste of decaf coffee isn’t the same as caffeinated, in the same way that Diet Coke, vegetarian bacon, or high-end MP3 players aren’t the same as what they started out as.

It’s good we call out differences between the original products and their derivatives, but at times it can seem a bit odd. As vegetarians, we enjoy a meat-like substance that resembles strips of bacon, but bacon it is not. Were it actually animal flesh we would not eat it.

The fact it isn’t what it purports to be is the reason we engage with it.

Take for example a product said to have a tube-like sound. We ignore the fact it is 100% solid-state because that description might not connect with our image of good sound any more than a package of Vital Wheat Gluten, Canola Oil, Adzuki Beans, and Buckwheat Groats seems appetizing.

It’s bold indeed to produce products that stand on their own merit and challenge stereotypes: AC regenerators, separate phono preamplifiers, CD transports, vibration control feet, active grounding systems.

I love the taste of a great cup of coffee, caffeine, and all.

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

AC receptacles

For those of us with long memories here’s a flashback. Remember when preamps sported rear-mounted AC receptacles to power the rest of the stereo system?

The first memory I have of the rear-mounted AC receptacle was on my father’s McIntosh C28 preamplifier.

Note the use of switched and unswitched outlets. The idea was that unswitched outlets were for the power amp and switched outlets for tuners and tape decks.

What a grand idea. Run your entire stereo system including your power amplifier through a skinny 16-gauge 2-wire zip cord.

What was it Red Fox used to put his hands up towards the heavens and cry out?

“Elizabeth! They’re coming for me.”

Some innovations are better left in history’s dustbin.

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

Teachers

I was filling out a group of standard internet security questions and the one that is almost always front and center stood out to me.

What is the name of your favorite teacher?

Of all the milestones we remember in our lives our favorite teacher is almost always a part of it.

Teachers shape futures.

When I was studying engineering my teacher was a hard, no-nonsense, by-the-book, German engineer named Rudy Ströebel. Herr Ströebel demanded I memorize the resistor color codes, formulas I would need, and schematic symbols and their meanings before he would begin teaching me. This was not a good way to absorb learning but, none the less, I wanted desperately to know and understand all he knew. The deal was made and off to studying, I went.

He wasn’t my favorite teacher though I owe Herr Ströebel much. Without his patience and guidance, I would not be who I am today.

Teachers shape lives.

My favorite was my 4th-grade teacher. I was her pet student and every afternoon at the close of school she would let me carry books and stacks of paper to her car—a brand new pink Cadillac with an electrically operated trunk—as futuristic to me as a flying saucer. With a nervous finger, I would press the trunk button under the massive steering wheel and up popped the trunk. It was pure science fiction. I loved that electric trunk and the teacher who let me operate it.

Whether teachers are from our past or in our future, they are wonderfully gifted, generous people the world needs more of.

To our teachers.