Asheville, North Carolina ‘s Home Theater and Audio specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.


Let’s get back to our basic subwoofer crossover today.

The purpose of the built in crossover is to make sure the subwoofer doesn’t play music higher than a specified frequency; that frequency specified by the user via a low pass filter control. Remembering the term ‘low pass’ means to pass the low frequencies, this seems simple enough to choose what point you want to have the music to not go through the subwoofer as the frequency goes higher.

For our example we’ll continue using 40Hz as the highest the sub is allowed to go. From there, we’ll assume it’s rolling off at 12dB/octave (remembering an octave is a doubling of frequency). This means our music is 15dB down at 80Hz (-3dB for the set point and -12dB because we’re at 80Hz, twice that of 40Hz). Let’s also assume our main speaker rolls off at the same rate as our subwoofer, 12dB/octave.

We want to set the subwoofer’s highest frequency somewhat below the lowest the main speaker goes. We want to do this because we’re expecting – depending – on a bit of overlap, meaning the sub and the main speaker produce some of the same frequencies in music at the point where they crossover – the top of the sub’s range, the bottom of the main speaker’s range. If both were set at exactly the same frequency, we’d likely get a bump up in sound as the top of the subwoofer will add to the flat response of the main speaker.
So, imagine our main speaker starts rolling off at 60Hz. Setting the subwoofer somewhat lower, at 40Hz, then makes sense because as the one is going up and getting softer in volume, we’re getting far enough away from the crossover frequency to minimize the overlap.
Using your main loudspeaker’s specifications is a good starting point to set the subwoofer’s maximum frequency on the low pass filter. But listening, playing around with the sub’s settings will be needed to get the smoothest transition at the point of overlap.

Asheville, North Carolina ‘s Home Theater and Audio specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Whoa, skippy!

My, my, there’s a lot of opinions out there. Thank goodness for that! I suppose a few hornets have been riled up by my comment of not rolling off the bottom of your main loudspeaker to accommodate the sub. I suppose that needs a little more explanation.

First, let me repeat an oft mentioned ‘Paul’s Rule’. The goal of any loudspeaker system, or for that matter any music system, is to disappear. There’s no higher compliment given than when people sit in Music Room One and ask where the sound is coming from because, ‘surely it’s not coming from those big speakers’. Those ‘big speakers’ disappear and that’s the whole point. Same with a subwoofer. The greatest compliment to any subwoofer installation is that it is invisible.

Think of food. The individual ingredients should be invisible if they were prepared properly. You don’t want to say to a chef ‘I can sure taste that basil’.

So the idea of a subwoofer is to augment the performance of the main speaker and then do so in a way that never draws attention to itself.

Now, on to the main topic, to roll off the bottom of the main speakers or not. I say NOT.

Why would you want to roll off the bass from the main speakers? Because of an effect known as Doppler distortion. Simple to understand, Doppler distortion describes that property of an object, like a speaker driver, to do two (or more) things at once. I know … that’s not entirely accurate … but it’ll do. If a slow moving woofer is also making higher frequencies at the same time as it’s slowly woofing, then those higher frequencies are being modulated by the lower frequencies causing a type of ‘muddiness’ or ‘muddledness’ to the sound. Better to have the woofs woofing and the tweets tweeting, never the two to meet. That’s the reasoning behind removing the requirements for bass from the woofer and assigning it to the subwoofer.

But here’s the thing. The methods used to remove that bass from the main speaker (yet another crossover filter) add more trouble than they remove. That’s my thought on the matter.

You know what? Your main speaker was designed, I am assuming, from someone competent enough to make it all work. Leave it alone. Augmenting it with a sub is smart. Changing its functionality is not.
Thank goodness I don’t have an opinion on the matter.

Asheville, North Carolina ‘s Home Theater and Audio specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Stepping stones

As some of you know I am writing a novel. It’s a thriller with a message. I am not sure what that genre of book is, or if it even has a genre. None the less, I am now at the point of hiring an editor for the book. I have taken it as far as I can on my own.

And it occurs to me this process is very reminiscent of high end audio tweaks. Why? Because taking something that’s good and making it better is what an editor does and what we try and do in high-end audio.

When I read, say, chapter one of the book it’s engaging. Those friends who have read it agree. But the editor has taken chapter one and completely flipped it around. Reworked perhaps half the words and now it’s better. A lot better. And when I read the original I cannot imagine how I liked it so much, now having read the revised version.

High end audio is much the same. Today I listen to something like our DAC and am happy. Tomorrow I update the firmware and it sounds ever so much more musical.

Degrees of improvement are like stepping stones along a path. With each step we get closer to better. It’s fun. It’s rewarding.

Asheville, North Carolina ‘s Home Theater and Audio specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Digital DNA

We have our own group of wizards at PS Audio. I might call them alchemists, but I am happier with wizards. Ted Smith, the creator of DirectStream DAC, is a great example of a wizard.
Ted just delivered to us a remarkable update to DirectStream. ‘Significant’ hardly describes the magnitude of improvement you’ll hear.

And it occurred to me that the modern ability to change the fundamental structure of a DAC; of any piece of equipment, is akin to reprogramming DNA. Think of it. We are physical beings. Each of us unique, yet each of us the same. It is our DNA that makes us physically unique; our characteristics controlled through a sort of biological programming.

In a sense we’ve been doing programming and reprogramming for years with tube swaps. A tube is the heart of an amplification device employing it. Change the tube type, change the sound; change its ‘DNA’.

A few modern DACs, like DirectStream, are also empty physical shells we can program to do whatever we want. Changing its ‘core DNA’ if you will.

This whole idea of programming hardware is still mind boggling to me. Yet significant in its implications.

We will release new code before the end of this month.


Asheville, North Carolina ‘s Home Theater and Audio specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Hotel system

As we prepare for RMAF (Rocky Mountain Audio Fest) it fascinates me to think of the task ahead. On the one hand we’re doing nothing more than any of our customers: setting a stereo system up in a room that isn’t appreciative of big speakers, cables and boxes. On the other hand, it is different: we have one day to setup, we can make no changes to the room, we don’t have a sweet spot to listen in, we have to have a rather large group of chairs.

It’s always interesting to me this challenge of audio shows. For the upcoming event in Denver we purchased a pristine pair of IRS Betas. These are the junior versions of what plays in Music Room One. To some, the IRS Betas are better than their larger brother, the IRSV because of the Large EMIM driver on the Betas the IRSV doesn’t have. I should also point out these speakers are a quarter century old. Yet, few modern systems I have heard in the ensuing years come even close. Such is the level of progress in speaker design.
The IRS Beta’s designer, Arnie Nudell, has kindly volunteered to set them up in the room. The same room I described above with all its frailties and restrictions.

The new PerfectWave Power Amplifier, with a tube input stage, will be front and center in this display. We’ll have two of them: one for the main panels of the system, the other for the servo bass towers.
We’ll also have a Sprout ‘lounge’. Nextdoor to the big system we’ll have a cool living room setup with Sprout playing a set of Golden Ear Aons, as well as Audize headphones to enjoy.

Should be fun and a provide an experience many people would like to enjoy. We hope you have a chance to come by and visit. We’re in room 550.

Asheville, North Carolina ‘s Home Theater and Audio specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.



9 + 3 and bliss or anxiety?

I had a bit of an anxiety attack recently over the installation of my new home theater. After going to CEDIA and hearing Dolby Atmos, the new 9 channel system Dolby is promoting, I was smitten and ordered even more loudspeakers for the room. Now, this proposed theater system, doubling as a music system, reminds me somewhat of a pin cushion: three speakers in front, two in back, one on each side, four in the ceiling, three 15″ subwoofers under the screen. That’s a LOT of speakers.

The intent, of course is immersion. The idea with multiple channels of audio is to envelope one inside the environment of the film. There’s even some multichannel music one can purchase for the same effect. In the front of the room a giant screen to occupy your attention, the lights low, the environment of the room seductive. And there you are, immersed in it all.

The man designing this wonder, and helping fuel my anxiety attack, is Robert Dreher. He’s great at creating an immersive environment. His theater is what convinced me to go for it.

Yet, I have this anxiety of going from two-channels to ten-channels. I know, I’m probably being a fuddy duddy, but speakers in the ceiling?



Asheville, North Carolina ‘s Home Theater and Audio specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

The last 10%

Reader Kevin Norton asked a great question. “If you put all your music on an SSD on the Mac Mini music server, would you get that last 10% you’re missing?”

It’s a truly great question because while I suspect the music will get better, the sound closer to that of the ideal, I doubt it’ll fill the 10% gap. Why? Because that last 10% is at least as hard as achieving the first 90%; if not harder.

Or put another way, and to quote our chief engineer Bob Stadtherr, “It’s hard enough to get the first 90% of the work done, but it’s the second 90% that gets you every time.”

And he’s so right. Building is hard enough: getting all the right pieces of the puzzle lined up and in the right places. But then the polishing, the struggle for perfection begins.

Building a proper foundation can take years. Achieving perfection can take a lifetime.

Asheville, North Carolina ‘s Home Theater and Audio specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Danger of words

We often use incorrect terminology. Take for example the terms “phase” and “polarity” when we talk of flipping the plus and minus of both channels at the same time. What we mean is polarity, but we often use the term “phase”.

Garry Gallo, a reader of these posts and an engineer, sent me an excellent description and picture of the difference between the two. Note in the diagram that A and B in phase differences are moved in time (left to right on the picture), but have the same direction (up and down in the picture). And Polarity Difference changes direction (up and down), but happen at the same time.

We all use the terms “phase” and “polarity” interchangeably, even though we shouldn’t. A phase difference is a difference in time, whereas a polarity difference is an inversion. When we reverse the leads on one of our loudspeakers, we often say that the speakers are “out of phase” even though they are really of opposite polarity. The difference between the two is best illustrated using an asymmetrical waveform. I’ve attached such an illustration – one I’ve used in several articles and conference papers.


Asheville, North Carolina ‘s Home Theater and Audio specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Mac Mini server

In an earlier post I detailed how to build a music server from a Mac Mini. It’s now up on our How To Section of the website if you’re interested.

I was, at first, quite happy with the sound. That is until the new power amplifier and IRS V setup in Music Room One. The improved resolution of the system was such that I became unhappy with the straight Mac Mini sound.

So, I sent it off to a modification service called YFS. Now it’s back and sounding considerably better.

Before modification I would have suggested the server sounded 70% as good as the PerfectWave Transport. Now, after modification, we’re closer to 90%. Spitting distance.

Here’s what they did.
• Added a Solid State Drive (SSD) and put the Mac’s operating system on that drive.
• Kept to 500GB hard drive with all my music
• Removed the internal power supply
• Added some proprietary filtering of the incoming DC power
• Added an external power supply

These changes made a heck of an improvement.
If you’ll recall, one of my requirements for the server is to be able to travel easily with it. The big boxy power supply they offer as part of their normal package was simply out of the question for me. I arm twisted a bit and got them to build a small, inline version that easily fits in my travel kit.

I’ll keep you up to date on the progress.

Asheville, North Carolina ‘s Home Theater and Audio specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.


Wikipedia describes Synergy as “the creation of a whole that is greater than the simple sum of its parts.”
And that’s what takes place with careful assembly of your audio system. One of the beauties of our passion to build great music systems is the mixing and matching of equipment.

Just think of it. While you might have much the same equipment as I do, or your friend does, your music system is absolutely unique. You have a different room at a minimum. Your choices of seating position, interconnecting cables, the furniture you place in your room to hold the system, even the very air you breathe is most likely different than that that I breathe; and air density determines much in the way your music sounds.

Never be afraid to experiment, to mix and match, to do what no one else has done. You already are, by default.