Audioholics On Location: Factory Tour #2 of Axiom Audio

Back in fall of 2004 we took our first trip to Canadian Loudspeaker Manufacturer Axiom Audio to check out their new super subwoofers - the EP500 and EP600 , and their manufacturing and testing facilities via our factory tour .

Needless to say, we were most impressed with the company, products and the Axiom community. We learned that the folks that work for Axiom do so because of their passion for the art of loudspeaker design and their commitment to building the best products possible within price ranges most mere mortals could afford. However, by digging a little deeper and spending a bit more time with these people, one comes to the realization that they don't work within the typical confines of the employer/employee work model. Instead, they operate more like an extended family of audio experts who love working together, sharing free time with each other, and benefitting from the synergy they develop working in a free-thinking, unconstrained environment.

When I asked Ian Colquhoun, owner of Axiom Audio, how and where they come up with new product ideas, his response was "we do most of our new product envisioning on the dock" . Be that as it may, I made sure to bring my swim trunks. Luckily it was summer, making the freshwater lake almost bearable for this Florida-boy who is used to swimming in bathtub-like water temperatures in the Gulf of M exico .

On our last visit, Ian drilled us with the National Research Council (NRC) gospel of loudspeaker design, stressing that if a loudspeaker isn't linear in an anechoic environment, it doesn't hold a prayer in terms of accurately reproducing music.

Editorial Note on NRC Metrics and Design Criteria
According to the NRC Research, an important goal in loudspeaker design is that the end product, when anechoically measured, produces a flat on-axis response with an even but constantly declining (or tilting) off-axis response. Ian is a firm believer in the "family of curves" (established by the NRC) and their ability to predict subjective performance and identify objective loudspeaker performance. The family of curves is comprised of:

• On-axis Frequency Response: direct sound; the first sounds to arrive at the listener's ears
• Listening Window: an average of responses taken from a ±15 degrees vertical, and ±30 deg horizontal window directly in front of loudspeakers
• Early Reflections: the first axial reflections from room boundaries
• Sound Power (sometimes referred to as "total radiated sound power") is measured in watts, though when referenced to 10, can then be expressed in dB's. It's a metric that represents the total amount of sound that radiates from a loudspeaker, in every direction. It's useful when you consider the typically un-anechoic acoustic character of a typical home listening space.

NRC practice is to first measure a loudspeaker's on-axis response, then rotate the system in 24, 15°

increments horizontally, for a full 360° assessment. The procedure is then repeated, this time rotating the system vertically, once again, in 24, 15° increments for a full 360° assessment.

From all these measurements, an average is generated and from the resulting data, the sound power curve is produced. If needed, polar response & the directivity index (DI) can also be derived from the data.

With that in mind, we questioned Ian about the Axiom testing procedures in accordance to NRC standards. He informed us that Axiom first tests its products at the NRC in Ottawa and then take those "golden units" to their mini anechoic chamber to run baseline measurements. Axiom then compares all production models to the reference "golden unit" to ensure they measure within ±1dB.

In the very near future, Axiom Audio will be building their own full size anechoic chamber to conduct detailed, accurate product testing convenienty in their own facility. Ian assured me, however, that they will continue to do baseline measurements at the NRC facility for comparative purposes. Axiom's chamber will be an actual clone of the NRC anechoic chamber and will be calibrated against it.

In addition to their mini anechoic environment for testing production speakers, they do all their subwoofer testing in a 4pi environment (in this case outdoors on a pole above any boundary reflections with the woofers firing up at the sky and the microphone one meter away).

Pictured to the right is the new EP500 strapped onto a long metal boom, firing upwards, with the measuring microphone placed 1 meter above the acoustic center of the cabinet. This is roughly equivalent to an anechoic environment, but much more practical since an extremely expensive anechoic chamber with linear dimensions on the order of 70 feet (1130ft/sec/16Hz) isn't required to validate that the new EP600 truly does play down to 16Hz without the assistance of any room gain.

In the Lab

As we learned from our last visit, Axiom Audio's testing facilities and staff are well equipped and positioned to develop state-of-the-art loudspeaker technology and much more. It's the "much more" we are all so curious about. I had to literally pry information out of their engineers by bribing them nonchalantly with more wine and spirits while sunning ourselves on the dock.

In one of their test labs I noted some very interesting test and measurement gear such as some vintage Brüel & Kjaer gear (which we have been told is fully restored and operational) along with an Audio Precision SYS 2722 - the world's most advanced audio analyzer (which, incidentally, Audioholics also uses for their measurements and analysis in our product reviews). The AP SYS 2722 is the type of gear essential for designing state-of-the-art electronics and for writing the industry's most comprehensive reviews. It's no wonder that great minds think alike as we found much commonality between Axiom's design philosophies and our own.

Editorial Note on Brüel & Kjaer Test Equipment
Ian informed us he uses the B & K test equipment to compare with LMS for reference purposes. Since the B & K is analog, it sweeps and measures with much greater precision and accuracy than LMS, especially at high frequencies. The disadvantage to it is you cannot upload the test data to a computer for analysis or graphical usage.

Their B&K test equipment consists of the 2606 measuring amp, 1022 beat frequency oscillator and 2305 level recorder.

A mixing console (left) in their main sound room (right) where they conduct double-blind listening tests during the product development phase.

When Tom Cumberland (Axiom's chief Hardware EE) isn't competing in M anly M an powerlifting competitions, he is hard at work measuring amplifiers on their AP SYS 2722 audio analyzer, using similar measurement techniques with respect to power, SNR and distortion as we do on this very same system in the Audioholics labs. We look forward to comparing notes when conducting formal reviews of their new products.

The world's largest vacuum cleaner (left) would likely make Mega Maid from Spaceballs envious. This system is used to suck the dust and tailings generated by Axiom's CNC robots, each busily machining raw wood products into various loudspeaker cabinets.

Audioholics Axiom On Location #2: New Products

Many of the new products from Axiom Audio are under development which means they are understandably tight-lipped about them. Though they were indeed tough as nails in telling me only what they thought appropriate, I did manage to eek out snippets of information from them which I am happy to share in this report.

New Loudspeaker Products

For years we've been bugging Axiom to develop in-wall speaker products to address a part of the market they were currently missing and perhaps underestimating. Their contention always centered on concerns of performance compromises in such products, mainly because they haven't heard any in-wall products from competitors that they were entirely happy with.

Just as with most other loudspeakers, care must be taken in the design phase. Selecting the right crossover topology and response is essential to properly manage boundary effects that result from having an in-wall speaker baffle flush with a wall. Secondly, it is crucial to minimize the energy transfer from the speaker system to the wall. The finest in-wall products usually sport back boxes to deal with this problem.

In speaking with Ian, he told us Axiom's design goal when developing an in-wall / on-wall product was to suffer no performance compromises. They wanted the in-walls to deliver the same quality performance consumers have come to expect from Axiom's box speaker counterparts, but with the convenience of occupying less space in the room. That being said, they felt the best solution was to develop a speaker that is fully enclosed, and partly in the wall, with the front baffle slightly protruding from the wall. A majority of high performance in-wall products with enclosures such as the RBH Signature Series must be installed during the framing stages of new homes since their enclosures are so enormous. M ost people don't have this luxury in existing homes, so a product such as the Axiom In-wall / On-wall makes good sense. Think of this speaker as a plasma on-wall type, but with the potential of a significant performance edge.

Introducing Axiom Audio's new In-wall / On-wall loudspeaker solution

This prototype (left) is the in-wall equivalent to the M3ti box speaker. Note the double ports on the bottom (right). This prototype had the wires running through the ports, but actual production models will sport traditional back terminal speaker connectors. Its back enclosure allows the speaker to achieve comparable box volume to the M3ti enclosure ensuring similar low end frequency response and even more importantly sound isolation from the wall enclosure.

Axiom plans on releasing a matching center channel shortly after the M 3ti in-wall hits the marketplace. Projected launch date is sometime late November of this year.

New Electronics from a Loudspeaker Manufacturer?

You betcha! With the enormous resources, talent pool, and test equipment of Colquhoun Labs you didn't just expect them to stay put designing loudspeakers, did you? Based on the excellent digital amp which is the heart of the EP500 and EP600 subwoofers, Axiom has taken this design concept to the next level by developing one of the industry's first high-performance full-range digital amplifiers. Granted, there have been a wide assortment of full range digital amp designs preceding this, but they usually employed low-pass filters on the output stages that interact with the reactive load of most loudspeakers. As a result, they had to be used with speakers with constant-impedance crossovers in order to maximize their sound.

For more information on this topic check out - The Truth About Digital Amplifiers

The Axiom solution differs in many aspects from traditional Class D PW M amplifiers:

• Fully complementary design from input to output - very few "audiophile" (or otherwise) linear amps maintain a balanced design though the output stages
• High switching frequency (500kHz clock with 1MHz Mosfets), which allows the Low Pass Filter (LPF) to be implemented well above 20kHz thus avoiding deleterious reactive-load loudspeaker interaction
• Fully analog power supply ensures maximum dynamic range and low level linearity. As you can see in the picture of the prototype I was holding, the transformer and capacitor bank are tremendous. Carry a few of these around the lab all day and you can skip your gym workout.

In discussing this amplifer design with Tom, he informed me that the design group at Axiom carefully selected the poles of the LPF so there would be no phase or frequency response shifts in the audio passband while driving 1-ohm to 8-ohm reactive loudspeaker loads. The amplifier utilizes a single-rail balanced H bridge design which further increases efficiency over a two-rail amplifier design, since the balanced topology allows the amp to track the rails perfectly for positive and negative swings. In contrast, conventional amplifier designs using two rail supplies must deal with the higher drop-out voltage on the negative rail, and less ideally, load balancing, which compromises efficiency and to some extent dynamic range during sharp transients.

Editorial Note on Class D (PWM) Amplifiers
Class D amplifiers utilize a technique called pulse-width-modulation, which is sometimes combined with pulse-frequency-modulation. The input audio signal is converted to a sequence of digital pulses whose width at any time is proportional to the amplitude of the signal at that time. The frequency of the pulses is typically 30 or more times the highest frequency of interest of the audio signal. Unfortunately the byproduct of the output of such an amplifier contains unwanted harmonics that must be removed by a passive analog filter. The output of such amplifiers usually works best with constant impedance crossovers since they can react a bit unpredictably with highly reactive speaker loads. This is why these amplifiers are best suited for subwoofer applications or specifically designed amplifier and speaker packages.

The main advantages of a class D amplifier are efficiency and space savings. Because the output pulses have a fixed amplitude, the switching elements (usually MOSFETs) are switched either on or off, rather than operated in linear mode like conventional Class A /B designs. This means that very little continuous power is dissipated by the transistors except during the very short intervals of on and off states. The wasted power is low because the instantaneous power dissipated in the transistor is the product of current and voltage, both of which are almost always close to zero.

The enormous efficiency advantage of this type of amplifier topology over traditional linear Class A/B is two-fold in terms of heat dissipation and power delivery to the loudspeakers. There are a wide assortment of so-called "audiophile" amplifiers boasting enormous power delivery into all seven channels while only utilizing one power cord. While we have strong viewpoints against the validity of the "all channels driven test", it is academically interesting to note that the manufacturers advocating it usually cannot meet their cherished specification. Consider the typical Class A/B linear amp with a single power cord, and actual efficiency in the ballpark of 40% (factoring in conservative transformer losses and power factor). The best case scenario power that the amplifier could deliver to the loudspeaker system under this test condition is 1800 x 0.40 = 720 watts / 7 channels = 102 wpc! This assumes ideal test conditions: line voltage held constant via a Variac (not a typical scenario in one's home), minimal transformer saturation, and not blowing any rail fuses.

In contrast, with the efficiency of Axiom Audio's new PW M amplifier in the ballpark of 96% (93% with transformer losses and power factor considerations), power delivery under the exact same test conditions will pretty much be double that of conventional amplifier designs! Finally a solution that actually can hit power specs even in the most unrealistic and uncommon test condition. Best of all, it doesn't require two dedicated 15A circuits or an amplifier housing the size of a truck.

They take it one step further by providing the ability for any channel to dump over a kilowatt of power to the speaker load at any given time. Of course this assumes the loudspeaker has a low enough impedance to source this much current and further assumes it could actually handle it, not to mention if your ears could! Most loudspeakers can't, and don't, but I would expect Axiom knows this and may be working on one that will complement this amplifier.

When I asked how they managed to create such a highly efficient design, even by digital standards, Tom informed me that they use a high-flux core toroidal power transformer which is very efficient (up to 1.2x rated current and voltage). This results in minimal core losses and I^2R losses in wire - a typical problem with poor transformer design. Axiom's massive power supply and efficient amplifier topology allows the amplifier to maintain a very high power factor of greater than 90%.

Editorial Note on Power Factor
Power Factor is the ratio between real and apparent power. It is related to the phase angle between voltage and current and is a simple way to describe how much of the current contributes to real power in the load. A power factor of one ( unity or 1.00 ) indicates that 100% of the current is contributing to power in the load while a power factor of zero indicates that none of the current contributes to power in the load. Purely resistive loads exhibit a power factor of unity, meaning the current through them is directly proportional to the voltage applied to them.

The beauty of this design is it provides limitless dynamic range and headroom allowing it to drive pretty much any conceivable loudspeaker solution to full power with minimal heat dissipation or associated losses.

No official product release date has been announced by Axiom, but we were told to keep a look out sometime early next year.

Audioholics Axiom On Location #2: Listening Tests

Moving camp from Axiom's production facility to the Colquhoun home, it was time for a listening session.

Our last trip here introduced us to the EP500 and 600 subwoofers compliments of Bobby McFerrin's duet album with Yo Yo Ma. The bass extension was most prevalent in this song and the Axiom super subs had no qualms producing it with accuracy and conviction. This time around, Ian loaded the room with two EP600's and two prototype digital amps with the rest of his speaker system and electronics remaining the same. With Alan Lofft and Tom Cumberland resting on the sidelines, I handed Ian a CD from one of my all time favorite rock bands, Marillion. The disc was " Holiday 's in Ed en ", which I feel is a great primer for potential new Marillion fans looking to get a taste of their fabulous sound.

For those who aren't familiar, I suggest checking out our extensive Marillion Band Interview and their music if you enjoy rock with substance, meaning and passion.

We started out with Splintering Heart, which opens innocently enough showing no signs of a dynamic rock song. Steve Hogarth's voice is simply astounding and the emotions he invokes in his lyrics simply legendary. The bass guitar was well pronounced and sound envelopment in DTS Neo6 was excellent.

Though this CD is a bit anemic in bass response, the EP600 twins did provide some oomph in the program material, especially at low volume levels. This is something I am sure Ian and his loudspeaker design group must be proud of. Design a speaker system to be linear and it is usually less fussy about the room you place it in while at the same time retains the ability to extract the most detail out of any recording at all listening levels, regardless of volume level position. The Axiom system was clearly demonstrating this.

We ran through the gamut of tracks in this CD. Pretty much all of them are excellent, but my personal favorite is Waiting to Happen, which I feel to be the ultimate rock song you can actually dance to. The Axiom folks like their music loud and clear and Ian certainly didn't use the volume control sparingly on this song. Ordinarily I like to listen at a more sane level, but Steve H's voice is simply mesmerizing and you just can't play their music loud enough in my opinion.

Next up were some bass torture tests starting with the Flintstones theme song from a bass demo disc Ian had on hand. With the twin EP600's handling the low frequencies, we discovered bass we never knew existed in this song, especially when being played on the typical 6x9 whizzer cone speakers found on the TV sets we all grew up with when watching this classic cartoon. It was hypnotic watching the EP600 woofers get quite a workout, and particularly impressive that the long woofer excursions were absent of audible distortion or bottoming out.

Though I felt a bit out of my element listening to a bass CD typically found in a teenager's boom car, it was an enjoyable experience hearing and feeling the EP600's belt out the low notes. My personal preference would have leaned towards some Steely Dan or Pat Metheny, but neither artist's music would likely satisfy the appetites of the various bass lunatics present or provide a true demo to marvel in the capabilities of these subwoofers.

Listening Impressions by Mark Sanfilipo

The subs delivered - with ease - very impressive amounts of very clean, low frequency acoustic power. We worked our way through various test tracks chosen for the audition; you could hear the various LF room modes loading and unloading as the system was put through its paces. Nothing unusual there. What was unusual was the experience of encountering the sort of wall-shaking dB SPL levels the subs were producing - and doing so as cleanly as they did - in such a reasonably sized package. Push these subs hard and the kid in you will laugh with amazement at the results.

Though there were moments during the audition I found myself wondering just how much acoustic energy the immediate structure could absorb before showing signs of stress and strain, I never got the sense we were ever near the limits of these sub's capabilities. The idyllic peace and quiet of the Canadian countryside just outside the glass wall of the lakeside home we auditioned the system in seemed an odd counterpoint to the acoustic mayhem going on, to the delight of all those present, inside.

Like any good sub, they delivered when called upon, then disappeared back again into the mix. These subs are not one-note thumpers for the faint of heart. The digital road map encoded in the subs' built-in power amp ensures - indeed, demands, the system reproduce with precision and musicality whatever source material you feed to it.

Add a sub or two like the EP500 or its big brother, the EP600, to your home system and you'll discover a new dimension to the music that makes up your collection. From sheer musicality to sheer impact, you're in for an exciting, refreshing listening experience.

Closing Comments

On my last visit to Axiom Audio, I walked away with a new respect for the company. My sentiments this time were much the same, except I was completely excited about the direction this company was heading in. They are attempting to position themselves to quickly become Canada 's leading loudspeaker and electronics manufacturer. The fact that they have the resources and engineering know-how to do it isn't as impressive as is the desire in their hearts and thirst for developing the very best products. It was clear to me that the Axiom Audio community loves what they do, perhaps equally as much as we love reviewing their exciting new products. These guys love going to work!

When I asked Ian's wife, Amie, why Ian always has a smile on his face and is quick to crack a joke, she said that (besides obviously having such a great wife) he has a clear conscience because he is following his heart, designing gimmick-free products and technologies he believes in, all firmly grounded on provable sciences and established engineering principles.

Axiom Audio has all of the necessary ingredients of an excellent company that many corporations could learn from, and although they are passionate about their work, they are equally as passionate at enjoying life's simple pleasures (ie. food, spirits, nature and most importantly the comradeship of each other). You get a sense of family when spending time with these people and their genuine kindness and thoughtfulness reaches out to their customers, in their support and service of their products. It's short-sighted to speculate that Axiom will be complacent limiting their design and manufacturing expertise to loudspeakers and amplifiers. We are expecting a great many things from this company in the near future and look forward to reporting on it. Though they haven't yet attained the magnitude of name recognition possessed by the likes of Sony, Mercedes, or Audioholics (LOL), keep an eye on Axiom: this is one sizzling company that will likely be known as a trend setter in a few short years.

Impressions of Trip and Country

This was our second visit to the beautiful Canadian countryside of M uskoka, and the lovely sights of nature never became tiresome or too familiar. Each time I gazed at the enormous and beautiful trees and unadulterated eco system it reminded me of just how artificial the more industrialized cities in the USA have become. It was hard for me to accept the fact that people actually owned a big chunk of land with a single home occupying what would normally be a cluster of homes back in the more developed areas of my hometown in Florida .

Ian and crew certainly picked a great location to run their business. Its isolation and seclusion is certainly an ideal environment for maintaining a clear and focused state of mind, although the temptation of basking in the warm sun of a beautiful summer day or jumping into a clear, brisk lake is certainly hard to resist. It was easy to see why the senior engineering staff of Axiom Audio generates most of their new product ideas on the dock, though I wondered just how much product development occurs during the remaining 8 months of the year when its unbearably cold (by my standards). Perhaps this is when they enter the production phase?

Additional Pictures and Sights

Here are a few shots of the cabin on the lake we stayed at during our visit to Axiom, which incidentally is where we later discovered the Colquhouns first met.

On the dock at the Colquhoun home, my wife and official photographer (left) is shown hard at work while we discuss the wonders of exotic cables, mystical CD mats, and the magical metaphysics surrounding them.

A beautiful Canadian sunset at 9:30pm at night!