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

Paul’s rule number two

In yesterday’s post we learned a little something about capacitors. They only work with AC voltages, like music signals. They do not respond to DC–battery voltage. The lowest frequency of AC that can pass through one of them (bass notes), is determined by whatever they are connected to and their size. The bigger they are, the lower bass notes they permit. These characteristics makes them incredibly useful in a number of application, from filters to coupling capacitors. It is the coupling capacitor we’re focusing on.

The only difference between AC and DC voltage is movement. AC moves from + to – at regular intervals (called frequency), while DC is un-moving, like the Rock of Gibraltar. A capacitor is a very handy tool for designers who want to separate DC from AC. When it comes to amplifiers, we’re only interested in getting the music from one end to the other. The power supply DC required to operate the amplifier needs to stay behind. Capacitors serve this purpose well. But they have limitations and they are not without affect on sound quality.

Paul’s rule number One: don’t be afraid to break the rules.

Paul’s rule number two is a take off on this old chestnut, no good deed goes unpunished.

Rule number two: No signal passes through any medium without change. Wires, capacitors, transistors, opto couplers, transformers–none are perfect, all change what passes through them.

Back in the days of early designs, coupling elements between amplification stages were common. Transformers and capacitors littered circuit boards passing audio signals. It was a safe and easy way to design circuits. As the art of audio design matured and people started acknowledging my second rule (one I certainly didn’t invent), new minimalist designs emerged that focused on removing as many parts as possible. The first candidates for execution were interstage coupling elements, capacitors and transformers, replaced by clever designs and dual voltage power supplies.

And today, most modern well designed hi fi electronics honor the minimalist design approach. But, a growing number of retro ideas are emerging: output transformers on DACs (well, at least one, our DirectStream), interstage transformers (like Mod Wright), and a bevy of other excellent sounding designs too.
We’ve learned over the years that great sounding hi fi designs are necessarily a compromise, blending the best of minimalism, new and old technology.

The constant is performance achieved by carefully listening before products get to market.

From these tenets spring fresh designs that delight the ear.

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

Optimizing limitations

Capacitors are limited in what they can do. And it is this limitation that makes them so valuable in many applications.

A capacitor is a rather simple device, and has nothing to do with flux; Doctor Emmett Brown’s time traveling DeLorean notwithstanding. The easiest way to describe its construction is to picture a sandwich rolled up into a tube. The two pieces of bread are conductors, the meat is an insulator. Here’s a picture of a film capacitor.

This was made by rolling our conductor/insulator/conductor sandwich into a tube and attaching a lead to each end of the roll. There are other types of capacitors, used mainly in power supplies, that are called electrolytic capacitors, but they are based on the same principals of the conductor/insulator sandwich, executed with chemicals rather than film and metal.

A capacitor only works with AC. Put a capacitor in series with a battery and nothing passes through the capacitor. But put an AC signal, like that found in music, and it passes right through as if the capacitor were a wire. How does this help designers? There are many cases where DC and AC are present at the same time, like the output of a tube or transistor gain stage. In most designs the DC is a problem for the next stage, the AC is all that we are after. Passing the signal through a capacitor at the output of a gain stage allows the AC to get through, but the DC is locked out. Just what we want!
But, of course, life’s rarely so simple as all that. Capacitors have limitations. Depending on their size and the load they are working into, only music above a certain frequency will pass through the capacitor. Lower frequencies, like bass notes, are left behind, along with the DC. This can be good if you want to have a rumble filter, bad if you want all the bass present in the music.

This frequency limitation can be put to good use, because if we want to make a filter–to eliminate frequencies above or below a certain point–the mighty capacitor is just what the doctor ordered. Its limitations are its strength.

Tomorrow, how capacitors were used before direct coupled circuits.

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

Back in the day

Back in the last century–we could even suggest millennium–we produced a power amplifier called the 200C, with two inputs: direct and coupled. Designed by Dr. Bob Odell in the early 1980s, this was a killer amp in more ways than one. The 200C, much to our horror, had lit on fire in the living room of TAS reviewer Tony Cordesman…but that’s another story for another post (and he loved the sound enough to buy the amp as well as a fire extinguisher). But I digress.

Two-input power amplifiers are common practice today: one RCA, one XLR. But in the early 80’s only pro gear had balanced inputs, and preamps could not be trusted. This era saw the rise of direct coupled solid state preamplifiers and they weren’t always done well. They could have high levels of DC (battery voltage) on their outputs; more often than not. If you build a power amplifier that is direct coupled from input to output, a pure path without any restrictions, that amplifier will perform its task perfectly, irrespective of what you feed into its inputs; AC music signals, or DC offset from a preamp. And if a power amp amplifies DC, small problems turn into big ones that can damage loudspeakers (and set amplifiers on fire).

We placed a lot of trust in our customers to first read the owner’s manual before connecting their gear. We were young, idealistic (and frankly naive–bordering on stupid), back then. We asked new owners of the 200C to connect their preamp to the amplifier through the safe Coupled input first. That was their default. It would protect from any preamplifier problems upstream. The Direct input should be used only by those who knew for a fact their equipment hadn’t any DC on its output. It didn’t take long for owners to discover the better sounding input was not the safe one. And anyway, how were they to know if their preamp’s were properly designed or not? Yikes.

The difference between the inputs was simple. There was a single high quality coupling capacitor inserted between the RCA jack and the power amplifier’s input. That capacitor did not help the sound, in fact, quite the opposite, but it could save the amplifier and speakers from trouble.

Tomorrow, the mighty capacitor.

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

Direct coupled…

…you don’t want it in a turntable, it’s rarely present in a tube output stage, it’s highly desired in a solid state circuit.

There’s perhaps a lot of mystery around some of the engineering terms we manufacturers throw at people–buzzwords that mean something to us, inspire confidence in buyers, and complete lists of must-haves for consumers. Direct coupled would be one of those words.

In a turntable, direct coupled would more commonly be referred to as direct drive. Instead of an interface between the motor and the platter, typically a belt or big rubber band, a direct drive turntable has a motor coupled directly to the platter. Most vinyl aficionados don’t like this because jerkiness or vibrations from the motor are transmitted straight to the cartridge. Instead, it is preferable to isolate the motor from the platter through an intermediary, like the rubber band, which absorbs and dampens motor irregularities.

Tube output stages would love to be connected directly to their next stage, like a speaker, preamplifier or power amplifier, but it is not easy to do. Instead, another interface is employed, like a capacitor or a transformer.

Solid state output stages–at least those after the 1970’s–are all pretty much direct coupled to speakers, preamplifiers and power amplifiers. And it is believed that the lack of another element, like a capacitor or transformer, helps the sound. Thus, manufacturers advertise the fact their products are Direct Coupled.

Yet times are changing, the pendulum swinging back to the start as it always does.

Let’s spend a few days understanding these tech terms.

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

Audio language

When we talk about sound, what do adjectives like, dark, wooly, bright, spacious, or edgy sound like on our stereo systems? Hard to say, because words build pictures in our heads that have no literal equivalent in sound. “Wooly” forms an image of “thick”, but how can sound be thick?

Just today I was trying to describe the sound of two products. Both sound full, rich, solid, and musical, though different when not compared to each other. Once I do that, however, a different description emerges: unit number one can now be described as dark, wooly and somewhat blurred, relative to the brighter, thinner, more focused sound of unit two. Auditioned in a musical, I use nearly the exact same terminology to describe both. Compared to each other, a new vocabulary arises.

The lexicon changes depending on what we are trying to show.

Broad relationships to real events, or minute differences between units.

I don’t envy reviewers their task.

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

Trying too hard

I am the first to admit my guilt. Sometimes I try too hard to force an outcome. Has that happened to you?

A friend suggests you try this tweak or that tweak and you don’t really hear the same thing. So you try harder, play more tracks that might exemplify the change they suggested.

It’s easy to confuse focus with convincing yourself. Narrowing the scope of your attention is valuable, listen for the better highs, increased depth, or richer tonal character. But working at hearing something you don’t often leads to false positives.

Scientists take a different approach. They work at disproving something, rather than proving it. And for me, that method often turns out more valuable over the long term.

It’s OK to narrow your focus to one suggested area. In fact, it’s almost always required, given the multitude of variables we are presented with. But be wary of convincing yourself something is so, if you’re not feeling it.

Question everything. If, at the end of your listening trials, you cannot shake the fact that A is consistently better than B, no matter how hard you try, then it’s easy to buy into 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, Inc.

Lossy and lossless

Computer audio can be hard to understand. I know this because I get so many questions from our customers. The (seemingly) most misunderstood terms are lossy and lossless, compressed and uncompressed.

For starters, how many of us get an uncomfortable feeling when we hear our music’s been compressed? It’s like hearing your food was frozen; it’s rarely as good as fresh when thawed. Messing with pristine musical content in any way, shape, or form, surely can’t benefit the sound. The best we can hope for is untouched, unmolested.

We compress music to save disc space. Some compression schemes take half as much space, while others a tenth, even one hundredth in some cases. But all compression schemes are not the same. Some throw away “unnecessary” bits of music to conserve space, while others sacrifice nothing. The names for the two types of compression, lossy and lossless, describe which loses data and which does not.

Lossy schemes include MP3, AAC, Dolby Digital, Ogg, and WMA. Lossless formats are primarily FLAC, and ALAC. File names like WAV and AIFF are not compressed at all. One everyone’s interested in as of late, MQA, is compressed, certainly, and uses a combination of both lossy and lossless to achieve its reduction in space. The designers claim to wind up with lossless if a decoder is used, a claim I have no reason to doubt.

How much loss can you hear? Much depends on two factors: who you ask and how much is lost. High bit rate MP3 can sound awfully good to most people, even on a decent system. Though, when you listen closely to your well know pieces, and on a high resolution audio system, the losses are evident: subtle details, low level harmonics in particular. But if you ask some sound engineers, reasonable levels of MP3 compression are inaudible. They have double blind tests to prove it too. Of course, these are the same guys who can’t hear differences in wires, formats or electronics, for the most part.

Lossless? Is it really lossless? There again we have several definitions. If, by lossless, you mean bit perfect, then yes, lossless files (after decoding) are identical to uncompressed files. But, if you mean to ask, do they sound differently, then that’s a much debated question.

To my ears a FLAC or ALAC file that’s been uncompressed, decoded, and stored as a WAV or AIFF file before being played, sound identical to the original. FLAC or ALAC files that are uncompressed, decoded, and played in real time do not sound the same.

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

Reading and watching material

First, let me thank the over 300 people who have contributed names for our upcoming magazine. Wow! Some great ideas. What a smart bunch of folks we have. I am always impressed by the quality and intelligence displayed by our community. Even more, the support, generosity and courteousness of each and every one of you.

While we were at CES a friend of mine, Michael Lang, publisher of one of Germany’s premier hi fi magazine, Stereo, has taken a big step forward. Stereo is an excellent German publication enjoyed by many throughout Europe. Each month I flip through the pages and try and figure out what is written. The editorial decided to invest what it takes to produce an English language version. And it’s free. If you’d like to check out Stereo, click the link and register to get your copy.
Meanwhile, the march towards renovating the building continues. I’ll post some pictures on the newsletter when we publish in a few days. In the meantime, I am bailing early and looking forward to Star Wars. Yup. Been waiting till the crowds die down. Our local theater offers reserved reclining seats, and we’ve picked the perfect ones.

Exciting. I am a fan of director J.J. Abrams and his Star Trek work, and I look forward to a good romp through the galaxy this evening.
Better than romping through the fume induced ozone I was in yesterday.

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

A bit of madness

It’s always fascinated me how events seem to come in waves and troughs: sometimes everything, then a whole lot of nothing.
Beginning last Friday we started a major remodel of the PS Audio building. 6 days later we had scheduled the server to be moved.

Chaos on both events.

Our building is not small. Our business is ongoing. So how do you renovate in the middle of business hours? Room, by room, area, by area. Old carpet’s removed, tile and new carpet are being added. Walls are sanded then painted – oh, but first, everything in that room has to go somewhere else – as do the people that work there.
Today was the worst. The painters had been rolling paint and the smell…well, not too bad. But today they tackled bigger rooms with high walls and the airless came out. So bad were the fumes we sent staff home. Within an hour, chemical spill alerts were triggered at our neighbor, Pfizer (yes, THAT Pfizer). A team of people in white lab coats holding beeping sensors and wearing worried looks invaded the building.

“All the alarms in our labs are going off. What are you doing? Is it legal?”
“Painting. Breathing toxic fumes. It’s horrible,” said I.
They measured, clucked, wagged fingers and left. Then the website went down. What was supposed to be an hour took 6. And PowerPlay is still down.

I suppose one could suggest we treat big change like removing a Band Aid. Do it all at one. “Ouch!” Others might suggest spreading the pain over a longer time. Me? I am still drunk from the fumes. A little disoriented at best.

The good news is the building will be gorgeous when it’s done.

The bad news is we have to apologies for the paint fumes.

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

Definitions

Yesterday I posted about vintage audio. One of the first questions asked, “what’s vintage mean?” That’s a great question. Vintage to me is likely different than vintage to someone a lot younger.
I had replied that anything in the 1990’s and older was vintage. I think that’s inaccurate. With the benefit of further thought, I would suggest anything in the 1970’s is vintage to me. But that’s because I am bordering on vintage myself.

What might a 30’s-something consider vintage? If I do the math, products half my age are vintage. By that same logic, a 30 year old would consider anything from the year 2,000 as vintage–a 30 year gap.

Definitions are, for the most part, relative. What is old to me is ancient to others. What sounds great to some might sound like crap to me. It is truly hard to define what’s high end, what’s this, or what’s that.

Most of us can tell, when pressed, if something sounds live or canned. I’ll give you an example. In my home we have only background music available in the living room (an equity trade for my downstairs home theater). It’s great background music, but nothing approaching high end. Most guests comment how great the music sounds in that room (I did add a sub and used decent speakers). I smile and ask them, “does it sound like there are musicians playing in the room?” I am always given a curious look. “Well, no, how could it?” Yet the same question posed to guests in Music Room One gives the opposite answer.

Defining common ground for language has always been a challenge. It’s all so relative.