Commentary on XTAC


A semi-random collection of personal thoughts and opinions on the XTAC Master Reference System, by designer Dr. Karl Schuemann, which have been bubbling up in my mind since the full system was actually up and running for the very first time:

Paradigm Shifts

Once upon a time, when I was quite young, my father bought one of the first HP handheld scientific calculators (for a small fortune). I still remember playing with his slide rule alongside it, and thinking about the paradigm shift that calculator represented, long before I even knew the phrase “paradigm shift.” Perhaps that was the first time I realized that the whole world, and our perception of what is possible in it, can change seemingly overnight. It has happened more than a few times since… laptop computers, digital cameras, smart phones, the internet… And while nothing we do in high-fidelity loudspeakers is comparable to something like the internet or the semiconductor in terms of “changing the world,” we nevertheless are looking for the same paradigm shift, in this case the final piece of the puzzle that will finally, at long last, get us from “this sounds like a loudspeaker” to “this sounds like real music.”

Until I was able to create and install the full XTAC Master Reference System in its complete form in my own listening room, there really was no way of knowing what it would do. Sure, the test vehicles were promising, but that doesn’t necessarily translate to a finished system. This concept, and this entire project, was not only “off the reservation,” it was off the map altogether, into completely uncharted and very deep waters. But once it was actually running, I knew almost instantly: I will never, for the rest of my life, ever make another conventional loudspeaker, ever again. In our little world of “high fidelity audio,” XTAC is a paradigm shift of such extraordinary magnitude that I really couldn’t fully comprehend it ahead of time. But now, as with seeing that HP calculator for the first time, there is no going back.

Conventional loudspeakers, even ones which represented the absolute “state of the art” in loudspeaker design only a few short months ago, now hold every bit as much fascination for me as slide rules: They are simply curiosities, artifacts of a bygone era, and far better suited for museum displays than everyday use.

Do You Believe Everything You've Been Told to Believe?

For several decades now, the loudspeaker has been the sole remaining “weak link” in the entire recording/reproduction chain, and by far. Every other piece has been optimized, and every other problem has slowly but surely been solved, to the point where it is possible to say that it meets the basic requirements of “high fidelity” recording and playback. From high performance microphones, to high-performance microphone preamps, to high performance A/D and D/A converters (please note that I am not including 16/44 digital in this statement, much less MP3), to high performance playback preamplifiers, ALL of them are now fundamentally adequate (or better) in ALL the basic requirements for “high fidelity” music recording and reproduction. All, that is, except the final piece, the loudspeaker, which in comparison to everything else could only have been described as “hopelessly compromised.” I have known this to be true for a long time now, and over time, it began to become clear to me just exactly what the problem was, despite what I had been told to believe by last-century audio “experts.”

An insight here and there, often separated by years or even decades, in seemingly disconnected areas:
1. The first time I heard a full-range electrostat as a teenager, many decades ago. Even then, I knew instantly and instinctively that there was something lifelike there compared to any dynamic speaker I’d ever heard. Of course, its compromises as a complete full-range speaker are so bad that in all my life, I have never actually owned one, but still… If you listen to a full-range electrostat by only paying attention to the upper midrange and above (above where the inescapable dipole problems really begin to rear their ugly heads), you notice something: It sounds incredibly natural and lifelike in those upper ranges.

2. The first time I heard a plasma tweeter, which by itself is… simply glorious. But more importantly, the first time I heard a plasma tweeter try to integrate with dynamic or horn drivers down below. The shock of going from something so obviously glorious in the treble, to something so obviously not glorious just
below it, with such a glaring and abrupt transition in sound quality, was something that stayed with me.

3. Over the years, noticing the same phenomenon in all “hybrid” speakers which tried to mate plasmas to dynamic speakers, or electrostats to dynamic speakers, or ribbons to dynamic speakers, and so on:

The transition from the (really quite good) performance in the upper frequency ranges, to the (really quite mediocre) performance from the midrange down, was always such a disappointment, despite many of these speakers being designed by very well-respected designers to very high standards.

For most of my life, like most people and most speaker designers, I found the (enormous) compromises inherent in multiway dynamic speakers to be “not quite as bad” as the (even more enormous) compromises inherent in every other speaker type, so that is where my effort and attention went. But I never forgot those formative impressions, and I spent many decades thinking about them. Eventually I began to understand the one thing that connected them all, despite what I had been told to believe all those years: They all have nearly ideal Time vs. Amplitude behavior. But almost no one else seemed to notice, or to connect the dots.

One of the most amusing articles I’ve ever read in my life was a review of the latest Quad full-range electrostat in a major print magazine (this was many years ago now….), wherein the usual measurements were published at the end of the review. And those measurements showed a really ragged in-room frequency response, as would naturally be expected of a dipole…. along with a nearly ideal impulse response, right next to it. And right after that, there was the editorial comment that its measurements (relative to the audibly quite good sound quality of the speaker, at least in its upper ranges) were “…enigmatic…”, meaning, to paraphrase: “I have no idea why this speaker sounds as good as it does, because it has a really bad in-room frequency response, and everyone knows that’s all that really matters in loudspeakers….” And I nearly fell out of my chair. The only enigma here is how an otherwise intelligent person could be looking straight at that ragged in-room frequency response, printed right next to a nearly ideal Time response, and be scratching their head as to why the speaker sounds so good!

This, in a nutshell, is the problem we face: Do we choose to believe what we’ve been told to believe our entire lives, that Time response in loudspeakers really doesn’t matter? That the horrible phase and time errors inherent in ALL dynamic drivers, and the varying time delays within and between drivers that we can’t possibly fix with physical offsets, and the criminal offenses committed by high-order crossovers against the possibility of EVER putting that delicate signal back together again (in the Time domain) the way it once was, really don’t matter? When everything we know about the human hearing system (which, in the 21st century, is a lot!) tells us that they should matter enormously?

There is a fundamental contradiction here: Either our ears can hear things we aren’t measuring yet, or they can’t. I believe they can, or else conventional loudspeakers would already sound like real live music, not like loudspeakers as they so obviously do. So the question is: What can we hear so clearly in the upper reaches of those electrostats and plasma tweeters and ribbons, that we obviously aren’t measuring yet? What makes them, if only (and unfortunately) in their own very limited way, sound so natural and lifelike?

And the immense “Elephant in the Room” here, the one which so many are trying so hard to ignore, is Time vs. Amplitude Fidelity to the original music signal. It Is The Answer, if only we are willing to open our eyes and see the light, and not blindly believe what other people (often with an axe to grind) are telling us about what “doesn’t matter.” The now-legendary Peter Walker was right all along: If a loudspeaker can’t reproduce a simple square wave with reasonable fidelity, it’s never going to reproduce music in a lifelike manner either.

Every single (other) piece of the entire recording and playback chain, from the tip of the microphone all the way to the final amplifier, is many orders of magnitude better than conventional historical loudspeakers, when it comes to Fidelity to the Original Music Signal in Time vs. Amplitude. So why do so many people continue to insist that Time doesn’t matter when it comes to loudspeakers? How can it matter in every other piece of the chain (so much so, that if any other piece of equipment did to the signal what any conventional loudspeaker does to the signal, it would instantly be labeled as the worst piece of garbage anyone has ever seen or heard, and hardly worthy of being used as a drink coaster!), and yet those very same crimes are utterly excused away when a loudspeaker commits those crimes? It really does matter, far far more than we would ever have imagined, given what we were told to believe by the mainstream “experts.” The only roadblock in the way of this truth was that before XTAC, no one had EVER, in their entire life, heard a single solitary loudspeaker system which actually solved all the major problems in “High Fidelity” loudspeakers simultaneously, so there was no way of knowing for sure. But remember this: Absence of Proof does not equal Proof of Absence. At last there is one, and only one, system in the entire world which has finally put this issue to rest, and confirms that yes, indeed, Time matters much more than we ever could have imagined, and vastly more than the so-called experts were telling us: The AudioMachina XTAC Master Reference System.

XTAC has been a true “labor of love” from the very beginning, many many years ago. I always knew, even from the very first “Aha!” moment all those years ago, that if the concept actually works in the real world, it just might be the most revolutionary advance in loudspeaker fidelity in my lifetime. And quite possibly in the entire history of the loudspeaker. Now that it actually exists, and it has surprised even me with its utter and unfailing naturalness, life, and faith to the original music, I believe that statement to be true.

Paradigm Shifts Redux

Having spent many years of my life developing XTAC to an incredibly high level of performance and refinement, and having now had some time to get used to its mind-blowingly real, natural, lifelike sound, it has been somewhat easier for me to wrap my mind around the idea of a paradigm shift of this magnitude as I’ve gone along. Such a thing will unfortunately not be nearly as easy for most audiophiles or recording engineers. Most audiophiles and engineers have never even considered the statement “Drivers Have Mass” to be a problem worthy of thought, because it’s simply not a subject that’s discussed in polite circles within the audio establishment. Sure, it’s fine to discuss the fact that drivers can now be made from beryllium, or graphene, or diamond, and to debate endlessly about which material is better, but to dare to think about (or even worse, to talk about!) the fact that every single dynamic driver ever made, regardless of type or cost, has not only mass and inertia, but relative to the delicate air around it, a whole lot of mass and inertia? To even discuss the physics of the subject requires stepping completely outside the “comfort zone” of traditional high-end audio.

So, while the scientific reality and the audible performance of the XTAC Master Reference System are indisputable, the very thought of an utterly revolutionary speaker technology may be more of a problem psychologically. Many audiophiles and engineers have their own egos wrapped far too tightly around their own audio system, and will desperately want to believe that the world really hasn’t changed overnight, and that their traditional speakers are really still just as good today as they believed they were yesterday. And that’s okay. We all face reality in our own ways (and some choose not to at all….).

But for those select few who are intelligent enough, and open-minded enough, and self-confident enough, to see (and hear) that the world has indeed changed before their very eyes (and ears), XTAC will be an absolute revelation and an almost incomprehensible source of ecstasy for the rest of their lives.

Truth vs. Beauty

For as long as I can remember (and by now, that’s a long time…), there has been an ongoing dispute in the audiophile world as to whether a loudspeaker should aim for “Truth” or for “Beauty.” Many a speaker, over many decades, has been labeled as “ruthlessly revealing” or “too syrupy” or any one of a thousand other such phrases, with much angst and hand-wringing among audiophiles. But what we never realized was that the entire argument was a red herring, and merely a byproduct of our lack of understanding of the absolutely paramount importance of correct Time vs. Amplitude performance. All those speakers, and all those adjectives, were, in the end, all the same: They described yet another speaker, in a very long list of speakers, whose Time vs. Amplitude performance was fundamentally wrong in one way or another. Some were badly designed in the Time domain, others badly designed in the Amplitude domain, and most badly designed in both. Simple as that, and the details of how that particular speaker was wrong were merely a distraction from being able to see the bigger picture: Namely, that this particular speaker, like all the others before it, did not produce an output which had correct Time vs. Amplitude performance across the full frequency spectrum, and thus, by definition, was not High Fidelity. But now, at long last, with the development of the AudioMachina XTAC Master Reference System, the entire argument can (finally!) be put away completely. The truth is that once you have a loudspeaker which actually reproduces the original musical signal correctly in Time vs. Amplitude, and meets all the other basic requirements necessary for true “High Fidelity”, the Truth (and with XTAC, for the first time ever, the real Truth!) is more Beautiful than you can possibly imagine.

Yes, It's a Powered Speaker

(Insert violins from the shower scene in “Psycho” here….)

And there’s no other way to do it right. The fundamental fidelity of XTAC would be so seriously compromised by anything else, that we cannot, in good conscience, even consider any other way. Yes, I know… from time immemorial, the “conventional wisdom” in high-end audiophiledom was that amplifiers and speakers could never be sold together in the same package, performance advantages be damned. So if that’s how you feel, well, it’s a free country. But don’t be surprised when someday you finally experience XTAC, and suddenly realize that you just wasted years (or decades) of your life listening to a bit of conventional wisdom that’s every bit as obsolete as your conventional speakers. While everyone else with an open mind has had a whole lot more ecstasy (or, dare I say, XTAC?) in their life.

The Sound of Silence

An extraordinary amount of effort went into making the XTAC Master Reference System incredibly, supernaturally quiet. (With the inherent efficiency of a line array this size, it had to be….) From insanely thorough power supply design, to meticulous circuit board layout, to individual parts choices, to incredibly well-thought-out grounding schemes, all the way to atomic-level resistor noise, it was an obsession to make this system absolutely silent in use. How silent? Let me put it this way: Many ultra-expensive preamps, including even some state-of-the-art solid-state designs, are noisier than the entire XTAC Master Reference System, including the 600W+ amplifiers!!! So when XTAC is placed in a well-treated quiet room, and when that level of silence is combined with the inherent lifelike quality of the system, the end result is truly eerie. The music truly seems to spring from utter nothingness, and transport you in both space and time…. one moment you’re in your comfortable chair, and the next moment you’re in a concert hall on the other side of world, half a century ago. Just make sure your upstream components have a similar obsession for silence, and just as important, make sure that you take the room acoustics and room treatments seriously.

I Wouldn't Do That If I Were You

If you are in the market for a new high-fidelity loudspeaker, especially one which might have been considered as representative of the “state of the art” in loudspeaker design before the existence of XTAC (and these days, could easily cost 10X as much as XTAC or more, by the time you add on the requisite amplifiers and speaker cables), please consider this advice very carefully: If you’re looking at spending more than $10K or so, please think very seriously about committing to anything before hearing the AudioMachina XTAC Master Reference System in person and at length. The world has indeed changed almost overnight, and although I couldn’t fault anyone for spending a few grand on a simple conventional speaker system (especially if they can get it at a huge discount) to “tide them over” until they can save enough to afford XTAC (after all, we all want to hear our favorite music…), I also would feel really sad for anyone who made the mistake of dropping serious money on a full-price conventional high-end loudspeaker system at this point in history, and then even more on amplifiers and speaker cables to drive it, only to turn around and realize very quickly that they are now the proud owner of a really nice matching set of boat anchors.

Attention, Mastering Studios

If I had to name one application for XTAC which is in more desperate need of its revolutionary capabilities than any other, given the far-reaching consequences to all of us, it is this: Mastering Studios. Knowing of the existence of XTAC, and once one comprehends what it can actually do (in terms of creating an acoustical output, for the first time in history, which is almost an exact copy of the electrical input signal, in real time, in a package which is ideal for installation into a dedicated room with a few well-placed acoustic treatments)… Well, let’s just say that if I owned or operated a mastering studio, and I had any pride in my work, I would be running, not walking, to the next flight leaving for Denver. And I wouldn’t want to put out even one more album without having XTAC up and running in my primary mastering room.

Attention, Reviewers

If you are a reviewer for any high-fidelity audio publication, whether on the recording side or playback side, and whether print or online, it is my honest opinion that you would be doing your readers (and your own reputation, for that matter) a grave disservice at this point by writing any further loudspeaker reviews without first having experienced XTAC in person and at length. And in virtually all cases, it would now be appropriate to have an XTAC Master Reference System in your own dedicated room, in order to have a true reference benchmark against which to judge any other review speaker which then comes through your door. Not to mention your own ecstasy while just listening to your own favorite music for pleasure.

You Can (Finally) Have Your Cake, And Eat It Too

The AudioMachina XTAC Master Reference System is “impossible” in so many ways that it’s hard to know where to begin sometimes. But in many domestic environments, I have a feeling that I know which particular asset will be the most appreciated: The ability to have an absolutely State-Of-The-Art, Reference-Quality music playback system in a package which causes absolutely minimal visual or floor-space impact. The sonic impression of this system, in comparison to its visual impression, is one of the most impressive things of all the impressive things about it. It just sits out of the way in the corners, and puts out unbelievable musical quality and (yes!) ecstasy.


In the distant past, when many of the large components making up a “High-Fidelity” music playback system were still quite compromised, it was considered appropriate to spread maybe 1/3 of the system budget on the source, 1/3 on the loudspeakers, and 1/3 on preamp and amplifier. More recently, it has become vogue to divert a portion of the system expense into cables, power conditioners, and other tweaks of various kinds, as the large components have steadily improved and even lower-priced high-end components are now really quite good in many cases. And that approach, historically speaking, has been appropriate, because there were always hundreds, if not thousands, of components to choose from in each category, most of which were quite similar in performance-to-price ratios, giving a wide choice to those looking for “High Fidelity” in their music playback systems.

But now, no longer. With the introduction of the AudioMachina XTAC Master Reference System, having XTAC as the final half of the playback system has very suddenly become more like an “absolute necessity,” if the real goal of the system is actually to be “High Fidelity” musical playback. Because without XTAC, the playback system, regardless of cost, simply no longer qualifies as “High Fidelity” under the new paradigm suddenly established by the existence of XTAC. Thus, the old priorities of budget-spreading, component upgrades, cables and tweaks, etc., crumble in the face of the reality of XTAC. Instead, because XTAC is simply so far beyond any other known conventional loudspeaker (regardless of cost) in terms of relative overall system performance advantage, as defined by the overall system goal of “High Fidelity”, it becomes more a reality of “XTAC first, everything else second” in terms of system priorities.

This reality means that it is suddenly easily justifiable to spend 90% (or even more) of the entire system budget on the XTAC Master Reference System and basic room acoustic treatment, because that one single leap in overall system Fidelity, brought by XTAC in a treated room, is so enormous that the relative contribution of everything else which could potentially be improved in the system, from sources to preamp to cables to tweaks, pales in comparison. This does not mean that nothing else in the system matters anymore– it absolutely matters hugely still, if the highest levels of Fidelity are important, that every single piece of the system represent the absolute “state of the art” in performance and fidelity, just as XTAC does. However, for those not on an unlimited budget but still desirous of maximizing the overall performance of their music playback system, the reality is that XTAC is now the keystone of the entire “High Fidelity” music playback system at this particular point in history, and likely will remain so for many, many years to come. In terms of budget priorities, if the cost of XTAC is reachable at all, even if it requires saving money for several years by not spending it on new components or cables or tweaks, XTAC should be Priority #1.

You're Welcome!

In terms of relative performance and fidelity to the original music, we could easily have charged 10X as much (or even more) for the XTAC Master Reference System, and easily justified it head-to-head against any Loudspeakers + Amplifiers + Speaker Cables of similar total cost in the modern world. Music lovers and reviewers everywhere would likely have agreed that yes, relatively speaking, it’s actually worth a million dollars (!!!) when compared directly to the most expensive conventional systems currently available in the world. But honestly, I would view that kind of greed as immoral and unethical, not to mention downright reprehensible. So we chose instead to set the sytem cost where we can afford to make it at only a very modest profit, rather than a completely obscene one (unlike some other modern high-end audio companies who shall remain nameless). Despite the world-class quality of XTAC in every way, we have been able to hold the total system cost of the XTAC Master Reference System (including amplifiers and speaker cables!) in the neighborhood of a high-quality (but not at all esoteric) automobile, something many people around the world buy regularly. Thereby, we have made it possible for literally thousands upon thousands of music lovers around the world to spend their days and nights with XTAC, rather than just a handful of privileged billionaires. You can thank us for this later, when you realize just how much sheer musical ecstasy the AudioMachina XTAC Master Reference System has brought into your life.

Happy Listening Forever!

Dr. Karl Schuemann