Tag Archives: woofer

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.


In the volumes of email I receive I get some great questions. Mark, in San Jose California, was asking why phono preamplifiers no longer offer switchable rumble filters.

I think it’s a great question. I remember years ago when nearly every phono preamplifier had a switchable rumble filter and I also remember hating it. Every time I clicked that filter all the bottom end of the recording seemed to vanish along with the unwanted woofer movement. Those high-pass filters of the day were pretty aggressive.

PS Audio has been building phono preamplifiers since our inception in 1974 and we have never offered a switchable rumble filter. However, every one of those preamplifiers had built-in rumble filters and that, Mark, is the most likely answer to your question.

By building in a fairly aggressive filter we can keep its frequency low enough so as not to negatively affect sound quality. We do this with a multi-pole high pass filter that has the dual role of keeping any small DC issues from occurring and, at the same time, eliminating rumble without impacting bass.

I am going to guess that what’s actually different is not the lack of rumble filters, but the lack of switches to toggle them on or off.


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.

On a carousel

Remember the old Hollie’s hit, On a Carousel? They were one of my favorite groups and, when Graham Nash left the Hollies to join Steven Stills and David Crosby, I was at first bummed but later fell in love with CS&N.

Being on a carousel, or as we Yanks might call it, a merry-go-round, can be frustrating. It sometimes takes a lot of energy to get off the rut we find ourselves in and make a change, but change is typically better than going round and round without forward motion.

I remember well when I was first hooked on electrostatic speakers. Man, I was on an electrostatic merry-go-round and for years no one could get me off of it. It had all started with my first listen to a pair of Quads. Holy crap! The transparency and window-like qualities of those speakers were magical. The fact they were extremely directional, had no bass, no volume, nor dynamics didn’t phase me in the least. I was hooked. If they didn’t have what I wanted, I could just go bigger.

Jim Stricker’s Acoustat electrostatic loudspeakers were my next acquisition and they solved the loudness problem because of their enormous size. Still, they had the head-in-a-vice directionality problem, no bass nor dynamics—but volume, clarity, and transparency were abundant. I even tried to add a subwoofer to these tall panels but back then, the subs were awful: slow, sluggish, and did not blend.

For me, the electrostatic merry-go-round was slowing down but it hadn’t yet stopped. After meeting Martin Logan founder, Gayle Sanders, I had to give it one more spin. Gayle’s electrostats were big, curved, and augmented with a built-in dynamic woofer. Nirvana! They could play loud, they had a bigger sweet spot, and by God, they had bass from that subwoofer. Still no dynamics. Still had to hold my head in a vice when listening, but….

Then the merry-go-round stopped and I stepped off into the magic of planars and lightning-fast dynamic woofers compliments of both Magnepan and Infinity.

I haven’t gotten back on the electrostatic carousel since. But, this isn’t a post about electrostats. It’s a post about being stuck on carousels.

If you’re stuck on a merry-go-round and everything you try doesn’t get you where you’d hope to be, consider hitting the emergency stop button and regaining your balance.

It’s better to go forward than in circles.


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.

Thrill seeking

Now that PS Audio engineer Chris Brunhaver has rebuilt the Infinity IRS woofer sections in Music Room II, tracks of music that once overloaded the room or underwhelmed the listener are back on the table.

Tracks like Deeper by Pete Belasco, When the Party’s Over by Billy Eilish, or Handel’s Organ Concerto Number 3 suddenly make more sense.

Before the woofer change, there was plenty of deep bass but it was more an effect sound than a real live note. Now, the system sends chills up your spine when those notes move both you and the room.

In fact, one of the joys of an upgrade to your audio or video system is the opening of new musical opportunities. If it’s better bass, you start looking through your library for tracks that demonstrate the new prowess. If a new tweeter or speakers with airy extended highs, you search for more thrills in that music.

If you want a few thrills and chills to challenge your system, and have Qobuz, you can access what we listen to by going here.

Have fun and give my apologies to the neighbors.


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.

A very good explanation of bass!


Isn’t it interesting that bass slam and quality comes not from woofers but instead from above?

Here’s what I mean by that. If you take a 3-way system like the IRSV, where the middle frequency drivers reproduce frequencies down to 100Hz, what you find is that bass impact and speed is determined not by the woofer towers, but rather the midrange drivers. Which is why we can accurately evaluate the bass performance of a power amplifier without that amplifier powering the woofers.

This applies not just to big systems like the IRSV. Just about any 3 or 4-way system will work the same way. Listen only to the woofers while music is playing and what you hear on a plucked bass note is little more than a dull thud. There’s no slam or impact to that sloppy thud because the frequencies that give the feeling of speed are much higher than the lower notes.

You can also listen just to the output of a subwoofer and get the same result: whoomp, whoomp, thud, thud.

It’s the upper ranges of bass that give us the impression of a fast woofer.


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.

Opinions and experiences

I am not a fan of passive radiators in full-range speaker cabinets. In every instance, I was underwhelmed with the sound of their bass and blamed the common denominator, the passive radiator.

A passive radiator is a woofer without a motor. Just picture your favorite woofer cone and that’s how a passive radiator typically looks. Were you to take it out of the box you’d note its lack of magnet and its light weight. Radiators act as tuned ports, lowering the speaker’s bass frequency cutoff to below what just its active woofer can produce.

My opinion of passive radiators has been negative for years.

Our opinions are formed by our experiences. If every beet we eat makes our stomach turn just a little then we declare our dislike of beets. Likewise, if every passive radiator we hear is muddy and ill defined we reject anything resembling it.

That is until we taste a beet we like or hear a radiator done right.

Our speaker genius, Chris Brunhaver, has opened my eyes and ears to the delights of a properly designed passive radiator. And what’s fascinating to me is that it doesn’t even look like a woofer. In Chris’ design a piece of heavy material, like wood, is the cone and it’s held in place with a carefully engineered surround material. Together, they form a tuned circuit that is sonically invisible in the same way a proper subwoofer extends the apparent bass of the main speaker without pointing to itself.

Little woofers can have big, tight, low frequencies with a properly designed radiator.

The point of this post is more about how experiences form opinions and less about radiators.

When we have the opportunity to extend our knowledge and venture out into the unknown, we often return with new opinions that are to our benefit.

I just love being wrong.


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.

Building beasts

Building speakers is way different than electronics. For one thing, loudspeakers can be handcrafted and designed from scratch, where electronics require cobbling together off-the-shelf parts. No one in our industry is likely to invent new semiconductor physics and apply it to hand made transistors.

The opportunity to design and fabricate every single bit of a product and technology is really stimulating. When senior engineer Chris Brunhaver joined the PS Engineering Team his first task was to wipe the AN3 slate clean and start over. Why? Well, the simple answer is because we’re obsessed engineering nerds and he could. But I owe you a more detailed answer.

Take for example the 12″ servo woofer used in the AN3. In the prototypes we demonstrated at Axpona the maximum linear excursion of that woofer was less than what the 700 watt amplifier driving it could output. This required us to place carefully crafted dynamic limiters on the amp and its servo system so we wouldn’t exceed the woofer’s limits. Sure, it output prodigious bass, but we knew the system was capable of so much more. Scouring the multitude of catalogs from the world’s biggest driver manufacturers didn’t help. Finding that perfect combination of suspension, excursion, BL, voice coil capabilities, and so on proved fruitless.

There was no perfect woofer for our specific application, and why should there be? Driver manufacturers don’t build woofers with us in mind. They make the best general purpose drivers they know how to.

Then, Chris joined our engineering team. The first thing he did was put pen to paper and sketched out a massive new woofer that would not only handle every last watt the power amplifier could dish out but do so within a linear range. The resulting beast is breathtaking. Have a look at the frames being assembled as I write this.

Holy crap this thing is a monster! But, it’s our monster designed specifically for its intended purpose. Every bit of it—from the spider, suspension, cone material and dust cap to the way the lead wires are hand-sewn into the spider’s fabric so they don’t rattle—this beast is perfect for our application. Nothing else in the off-the-shelf-world can compete.

More to follow, but I wanted to share my excitement with you.

We’ll be demonstrating the next round of AN3 prototypes at the upcoming RMAF at the beginning of September.

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.

Not that long ago

While looking at a replacement woofer for a friend of mine, I noticed its huge magnet and metal encasing shield. Ah yes, I thought, the magnetic shield that was all the rage a few years ago.

That shield was needed to protect cathode ray tubes from TV’s which use magnetic steering to position their controlling electron beams. Those electron beams had to be pointed at precise locations to light up different colored phosphors.

Ray tubes! What Buck Rogers technology was this?

Of course, I am referring to the old style television tube known as the CRT: small glowing tubes that grew in color range and size over their 75-year reign. The largest commercially available model was about 45 inches and weighed several hundred pounds. Larger TVs were technically possible but not marketable as the depth, weight, and cost made them difficult to sell. A 50-inch TV would require a 38-inch picture tube and even larger casing, making it near impossible for the TV to fit inside a standard door (let alone be hefted by mere mortals).

CRT televisions were finally phased out as late as the 2000s and replaced by plasmas, LCDs, OLEDs, LEDs, etc. The newer technologies are insensitive to magnetic fields, and thus, the need for magnetically shielded speaker drivers has vanished in little more than the blink of a technological eye.

Still, does any technology sound more high tech and futuristic as a fricking Ray Tube?

Buck would probably shed a tear for the passing of ray tubes into the boring of Light Emitting Diodes, so too would his contemporaries: Flash Gordon, Jack Swift, Brick Bradford, Don Dixon, Speed Spaulding, and John Carter.


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.

Lightning fast

At the risk of beating this poor horse to death, I thought I’d cover one more servo woofer item.


We don’t normally associate woofers with speed. Slow and ponderous, woofers struggle to get out of their own way. But it’s not their fault. They have a heavy load to move around, the mass of their cones.

When a bass transient occurs, the speed of the woofer can make all the difference in the world.

Imagine a big bass drum and a musician’s furious whack of the mallet. That whack occurs quickly and the transient response might resemble the instantaneous abruptness of a square wave. The quickest bits of the mallet’s whack are reproduced by the midrange or midbass driver and the rest by the woofer. If the speed of one does not match the other a discontinuity occurs and we say the drum doesn’t have the snap it should.

It’s easy to see why. Woofers generally cannot reproduce square waves on their own. The quick start and stop of transients aren’t reflected in the woofer because of its great mass fighting the forces of inertia.

Enter the servo woofer with its accelerometer-based motional feedback system that compares the woofer’s movement (or lack of it) to the demands of the input signal. The mallet’s whack demands a near instant start and stop yet the driver cannot respond because it takes time to get moving. In even the best woofer systems this is a problem because they have no means of circumventing physics.

Sir Isaac Newton will not be denied!

Yet, the application of a motional feedback system means we can augment the laws of physics by applying a disproportional amount of power to compensate for inertia’s demands.

Which is why a proper servo bass system is the only woofer technology I know of that can keep pace with the demands of music.

And, since the sole purpose of our new speaker line is to honor the music, an accelerometer-based servo woofer system is a prerequisite for a full range setup.

It’s lightning fast.

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.

Inside looking out

There’s a very important picture within each of us, one we believe represents our persona.

It’s almost always wrong.

It’s wrong because of the constant conflict within our heads: I am good at this—well, maybe not so much. I am really bad at that—well, I’ve been better in the past. I’ve heard much better sound out of cheap speakers!—well, maybe not. This doesn’t make sense!—well, enough people say it does so I am probably missing something. I am sure this sounds right!—well, the others don’t agree.

On an on, round and round it goes. Self-confidence battling self-doubt. New information erases or modifies what once was fact: corner horns are the ultimate, detachable power cords violate the wishes of the designer, one big woofer is better than multiple smaller ones.

Often the noise in our heads can overwhelm us to the point of searching out third-party opinions to hide behind. It’s sure easier to make a decision based on an expert’s opinion than to bravely step out on the ledge and take credit or blame for your own thoughts.

But then we always have to come back to reality when all the noise in our heads goes to sleep. In the quiet hours, we can relax and examine the fruits of our decisions: does the system really achieve what we had hoped for? Is there a nagging sense that it might make someone happy, just not us?

It’s hard to find what really works for us, to be brave enough to say “it’s right for me”.

When we take a stand we risk the judgment of others.

But, when we’re confident enough to make ourselves happy that’s the point of greatest joy.

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.

Midrange bloom

Comparing the sound of two full-range loudspeakers systems can only get you so far. You can tell they are different but unless those differences are narrowed to only a few areas it’s nigh impossible to know what to change.

Such was the problem of the PS Audio AN3 AMT tweeter and midrange duo compared to our reference Arnie Nudell pair. Once the two measured close together we fired them up with a variety of music but it didn’t take long to get overwhelmed by the differences. The AN3’s DSP based bass servo system is so strikingly better than the older Genesis Technologies leftovers, or even the Infinity IRSV servo system, that we had trouble focusing on the target midrange/tweeter combo.

It didn’t take too long before we used the Learning Funnel to narrow the problem down. Turning off the AN3’s active midbass and servo woofer sections to compare just the two made life a lot simpler though it took some adjusting. Because the tweeter/midrange section only go down to 500Hz there’s a lot of music’s essential frequencies missing—like listening to a tiny 2″ speaker on an old transistor radio.

Yet, even with the lower frequencies turned off the differences were easy enough to hear. Arnie’s reference speakers had a lower midrange bloom we weren’t hearing in the AN3. We looked closer at the measurements but were still befuddled as to the cause. Both systems had 2-pole high-pass filters at the bottom of the midrange ribbons and both measured reasonably close. Yet, there was that lower midrange bloom the AN3 lacked.

Then, as if a light bulb flicked on, the answer was staring us right in the face. I can’t remember if it was engineer Darren Meyers or Bob Stadtherr that first saw what should have been obvious. The Nudell reference used a long Bolender Graebener ribbon with nearly twice the length of the AN3s folded ribbon. Bingo. That larger area of coverage provided an increased level of energy at lower frequencies in the room in the same way an array of tweeters cumulatively go lower than a single tweeter can.

The fix was easy though it meant the measured curves were no longer the same. Now the AMT’s advantage of greater dynamics and its effortless means of squeezing air as an accordion does became apparent.

In hindsight, I suppose we could have figured this out with measurements alone but that’s just not the way it works best.

Our ears are still the best measuring tools we have.