User Feedback on the Axiom 300B Amplifier


Alliance Audio Axiom Amplifier reviews – based on Axiom Listening Sessions in Dallas

The following nine reviews are feedback from four days of Listening Sessions that took place in Dallas with the Axiom Amplifiers installed in Azzolina Audio’s Reference System. We asked the participants to focus on what they thought needed to be improved. They did a great job and suggested an area of Music reproduction that could be improved. On Saturday, we installed a different 300B tube in the amplifiers. This proved to be a much better choice for the speakers and everyone who heard it thought the Magic was there. We will continue to evaluate the sound performance of various brands of amplifier tubes to select two or three types that will allow Axiom Amplifier owners to voice the amps to realize optimum performance in their Audio System. (Dennis Boyle).

Bob Spence – Maxxhorn Please allow me to set the stage for my first listening experience with the Axiom 300B amplifier. After several months of anticipation, I was recently invited to a special unveiling of the completed pre-production prototype, which has been in research, development, and voicing now for over seven years. The Axiom is an Alliance Audio product that was developed by Bob Hoekstra, Peter Chappell (a transformer designer in the UK) and Dennis Boyle of Chimera Labs, with the invited input from numerous audio enthusiasts like you and me.

I am very familiar with various 300B amplifiers having enjoyed them in my home, and in the homes of several friends over the years. Their sweet midrange is legendary. It is apparent to me as well as others, that in spite of the midrange sweetness, many traditional 300B amplifiers are frequently rolled off in the highs and in the lows. In addition, the noise level (harmonic distortion and noise floor) is frequently a distraction with highly efficient loudspeakers in the preferred zero feedback implementation. Despite these observed weaknesses, the 300B amplifier is still a favorite of many audio enthusiasts. 

In evaluating any new product, I prefer my own home with a familiar system and music. On this occasion, I was invited to a close friend's home, who I had visited only 10 days previously to enjoy listening to music. Having been to his home many times, I am very familiar with his room and his system, which is superb and very revealing. The primary change on this occasion was the addition of the Axiom 300B monoblock pair amplifier.

When I arrived, some of the guests had been listening for a few hours. No music was currently playing. After greeting the other guests, I was offered the center seat. The Jack Johnson, In Between Dreams, album to be played, was familiar to me. I had heard it before with three systems and thus with three different amplifiers.

From the very first chord played, I was stunned by the beauty, transparency, and textural completeness of the Axiom. Within a few short minutes, I turned to Dennis Boyle and reminded him that I was on the waiting list for the Axiom. I inquired just how soon I would be able to take delivery. My mind was already considering which amplifiers in my collection would be sold to raise the needed cash. Obviously, my drooling had gone unnoticed by him, as he quickly passed over my comments. He asked me what I thought about the Axiom. I was a bit surprised by his questioning since, I thought I had just answered him in the most complete and complementary way, paraphrased, "I wanted this amplifier and I wanted it NOW!!!"

I told Dennis that the very first note I heard through the Axiom, on the System I am familiar with, had convinced me that these were spectacular amplifiers. He passed my comment off, with a wanton chuckle! "Had Dennis as one member of the Alliance Audio team become far too close to the project to hear what had been truly accomplished?" I thought. Assuredly, he knew what the team had achieved, but Dennis wanted more from me. His body language made me realize that a more in depth evaluation was expected in order to better provide the team with the necessary feedback they required on the final pre-production prototypes. He wanted confirmation that their exhaustive efforts to offer the very finest amplifier ever conceived - the "straight wire" with gain in its finest implementation to date had been achieved.

It quickly became apparent to me that I had been so completely drawn into the music as to be experiencing a rare Live Music Performance in the Home experience. a flash back to my days as an amateur musician surrounded by live and un-amplified piano, guitar, and orchestral music. I continued to listen for a couple of hours. I then asked to come back the following day for additional listening. I listen about four hours total on two separate occasions.

In short, I have found an amplifier that fulfills the promise to totally get out of the way. the "straight wire" with gain taken to perhaps the most complete iteration to date. For the record, I fear I have been unable to completely satisfy Dennis and the team with the detailed critique they desire, because there is absolutely nothing I can suggest to improve the Axiom's performance. I have no words that will justly express what Bob Hoekstra and team have accomplished. As such, superlatives become trite and hollow when I review my written words describing my actual listening experience.

My efforts to analyze the Axiom based on the usual shortcomings/imperfections compared to this and that reference amplifier leave me dumbfounded. No amplifier that I have previously heard comes close enough to be used as a comparative reference! As an amateur musician, and a passionate audio enthusiast, to me the Axiom 300B provides perhaps the best and purist musical reproduction by recalling only my many experiences of live un-amplified musical performances, thus revisiting the obvious realization that the live music reference is and should be fundamentally the way all reproduced music should be evaluated. From my experience, the Axiom is therefore perhaps the only amplifier up to this high level of expectation. 

Having stated above what is now obvious to me through my extended listening experience with the Axiom 300B amplifier. I am aware that my comments will be of little benefit to those who have not had a personal listening experience. I encourage you to listen to the Axiom 300B.

For those who seek reassuring words in print, I offer the following comments in a somewhat feeble attempt to do justice to this remarkable amplifier. The Axiom 300B is dynamic with excellent extension top to bottom. It is linear and well balanced. The highs are airy, crisp and harmonically complete. The bass is full, yet deep, tight and well defined. The instruments are easily identified by their characteristic nuances, and the textural purity and layering are fully revealed by the amplifier's pure and unique design implementation. Then there is the glorious 300B midrange…Yes even the midrange is very much improved, via a much lower noise floor,  resulting from the much lower distortion specifications, and the purer signal path design. The wonderful sweetness we expect in the 300B midrange remains. The soundstage is truly holographic with life-sized performers occupying their proper place. The presentation is remarkably open and transparent, yet rich in its harmonic complexity. The Axiom 300B amplifier presents a coherent and complete detailed spectrum that offers decidedly more than excellent macro and micro detail retrieval. The fast transient response and life-like decay of the piano notes and plucked strings are unsurpassed to my well-educated and most experienced ears.

Charlie Azzolina-Michlin - Azzolina - Ever since I started to listen critically to audio systems I have always been perplexed by how differently amplifiers sound from each other. So much attention is given to the other components and the question is often asked: “which is the most important?” In the end I believe this is the wrong question, they are all important. They all have to be good and work with each other to have the resulting music be as good. The combination is probably more important than any of the individual components, the amplifier/speaker matching being one of the most crucial interfaces.

When I was trying to figure out how best to demonstrate my speakers I had come to the conclusion that I would need three types of tube amplifiers for the different tastes people have or camps of theory they came from. One would be a push pull, one an ethereal type SET (45, 2A3 or 300B), the last a transmitting tube or “big” type SET (845, 211, 6C33). They all do different things well after all and variance makes a horse race.

After several days of having the Axiom’s in my system what struck me most about it was the way it covered the three different spectrums of performance. It had the midrange and inner detail I expected with a 300B. More of it than most 300Bs I have heard, resolving the time space relationship more like a 45. High and low frequency extension was more like a push pull than I expected exhibiting driver control and damping and bringing both extensions to a point most SETs don’t even aspire to. Along with these virtues it had the dynamic presentation full of color and authority more like an 845.

This competence in the different camps had me off guard for at least a few of the days I had the Axioms in my home. I have heard so many amps that I have expectations and I am not used to one doing so many different things well. Certainly it is unique in my experience. I tensed against them a little at first, expecting them to make me tired. Such a dynamic, authoritative amplifier is usually fatiguing. I did not find that to be the case here. In fact this continued to occur in different regions of performance the Axioms kept surprising me. I had to open my ears and expectations more than once to fully appreciate them.

In conclusion I have to say that the Axiom is the best amplifier I have heard in doing all of it well. There are amps which can do particular areas of performance better. I still love the 45 for instance but there is not another amplifier I can think of that comes close to doing all of it nearly as well. It easily exceeds many amplifiers in their own camp while exposing them for shamelessly falling short in the others. As a result I must state that the Axiom is a ground breaking product and sets a new bar of performance and musical satisfaction. It appears that it will mate well with a wide variety of speakers and I look forward to owning a pair and demonstrating my speakers with them. I expect these are probably the finest amplifiers to be had at any price; certainly they are the best I have had the personal experience to enjoy.

Cedric Meza - June 17th 2006 - Axiom 300B Listening Impressions - System components included laptop computer, Azzolina USB DAC, Azzolina Horn speakers, and Chimera Labs cables. 

My first impression of the amplifier was that it had ultimate clarity and detail without sounding sterile or harsh.  I was overwhelmed by the clean dynamics and transients that I can not recall hearing in any other amplifier.  This quality is addictive.  Being a single ended amplifier, I expected great mids with rolled off highs and bass.  What I heard was an excellent midrange with extended bass and highs.  I have not heard better defined bass from a SE amplifier.  The amplifier plays effortlessly and I experienced no listener fatigue. 

One reason I enjoy listening to single ended amplifiers is for the emotional connection I experience with the music.  The only fault I had with the Axiom 300B was that I did not connect to the music as much as I would like.   It lacked a bit of that DHT magic.  If the Axiom is a 9 or 10 in every other category, it might be an 8 here….Still very good.  My experience tells me that that we can fine tune this effect by swapping tubes. Overall, I found the Axiom 300B to be a very special product that will become a benchmark over time.  I waited a very long time to listen to this amplifier and it exceeded my expectations.  I have decided to purchase a pair of these spectacular amplifiers, and I eagerly await their arrival.

Scott Sheaffer - I had a chance to visit Charlie and listen again after Wed. I thought the Axiom's performance was quite high in areas of precision and accuracy, particularly with digital. The digital live cuts we heard were convincingly real. Cymbals and transients had realistic snap and speed that could fool you easy. In sound performance, these rank with the very best I have ever heard with regards to accuracy from midbass upward.

Dynamically, I felt that the amps were somewhat flat, both micro and macro dynamically. They are certainly powerful enough, but it seemed a bit like small and large sounds were coming out at similar volume levels - quiet sounds raised, loud ones reduced. Small "nuance" dynamics like voice inflections, vibrato, and string bends seemed restrained/under emphasized on Charlie's system.

Maybe "rigid" is the most appropriate description. I felt that the music might have been holding its breath and this reduced my emotional connection.  I was always analytically involved, as the Axioms render inner detail like few (if any) other amps I have ever heard. For me, it’s the emotion in sound that makes me go into the "I will die if I don't procure this gear" mode. 

I don't want to downplay that these are damn fine amps; I am just shooting you straight! I would expect the same. You will likely sell every single Axiom you make, BTW.

Ken Leibowitz - Thanks so much for allowing me to be there for the "unofficial" debut of your Axiom amps. It's a bit difficult for me to unequivocally give my impressions of the amps, since I was totally unfamiliar with Chuck's system as a whole. Being able to determine the amps contribution to the overall sound will be something of an educated guess, so for what it's worth. . .

As you may know, prior to my current GR Research Alpha LS line array speakers, I owned the Bob Spence & Johan Von Zyl designed "Immersion" horns. Prior to that, I had British-made Beauhorns, which used Lowther DX-4 drivers, as well as an Art Audio Diavolo 13 watt 300B SET amp, so I'm familiar with the sound of horns, Lowthers and SET amps. Much of what I heard yesterday reminded me of the things I enjoyed most about them.

As good as Chuck's amps sounded, I heard an immediate upgrade in the sonics when the Axioms were substituted. The sound field opened up with greater clarity and a feeling of power. all with a wonderful sense of ease.

The strength of an SET is of course the midrange, and the Axioms didn't disappoint. Jim Reeves singing "The Blizzard" almost made me cry. I find the song itself very touching, but heard thru Chuck's Gran Sfera speakers with the Axioms, it was in a different league. With my eyes closed, it sounded as if he were standing between the speakers. 

With the proper amps and source material, horn dynamics can be breathtaking. I certainly experienced that yesterday when listening to the Wagner CD. Even though it was played at a volume level way too loud for normal listening, the amps seemed to behave very well, without exhibiting distortion or clipping. Pretty amazing considering the level of bombast taking place.

I know you're seeking ways to improve them, but I really didn't hear anything that would require a fix. I suppose that's a good thing. Thanks again, and best of luck.

Jim Rivers - I've built 300B amps myself and have owned or listened to several manufacturer's 300B attempts. I was very impressed with the Axiom amps. I listened on a Wednesday and a Saturday session. I heard no distortion even when pushed to SPL levels much higher than I would normally listen. 

Wednesday, the Axiom amps had my toes 'a tappin. With both vinyl and CD. Always a good sign. Different configurations were tried and we were able to listen to music through two different turntables and the amps were truthful to both. Telling me the differences in the turntables, arms and cartridges we tried.  Again a good sign when changing front end equipment is so noticeable. The amps weren't masking the sonic signature of different sources.

I was so impressed that I now look forward to hearing them drive different speaker systems. Hopefully some day soon? Both days and even with different 300Bs, turntables and such the sound was always clean, articulate and without fatigue. This took place over the entire time I was fortunate to be in attendance. Can this be the 300B amp to end all 300B amps? They just may be.

J. Semrad - Although my time spent listening to the Axiom amplifier was limited, I came away with a very favorable opinion.  One of the complaints many people have about single-ended 300B amps is they are "colored", that is, they have audible distortion.  The Axiom puts this stereotype (no pun intended) to rest.  They have NO audible distortion, especially in the midrange. Furthermore, the Axiom has the ability to resolve the finest details a recording has available.  All in all, one of the finest single-ended amps I have listened to.

Tim Nickerson - I enjoyed the session. I was able to hear the body of the piano and cello with these amps.  Female vocals were great on Ella Fitzgerald and Joe Pass CD. I wish I had brought more favorite CDs. I look forward to hearing the Axiom Amplifiers with different speakers, Amps sounded great in Chuck's (Charlie Azzolina) system with his horns. Bass was very realistic and I experienced sound I never heard from that CD before. 

Ka Yeung - Thank you so much for hosting the Axiom listening session, it was very difficult for me to judge the amps in a totally unfamiliar system, I like the smooth open and grain free and delicate presentation,  I would love to hear the production amps in my system when it is available.

David Burna David Burna – David’s Audio System consists of a Heart 6000 CD player, a top-name SET 300B Amplifier and the Horning Perikles Ultimate Loudspeakers. 

The Axiom is a stellar design and a tremendous sounding amplifier. It’s quite an achievement. This amp has really, really low levels of distortion. In comparison, my amp sounded like someone threw a blanket over the speakers when it played. The Axiom took everything we threw at it and handled it beautifully….Solo piano, acoustic guitar, badly recorded Sun recordings…..all handled without strain or seeming effort. Towards the end we blasted some Wagner (Ring Cycle) and it was pretty darned loud, yet still absolutely clean. I could be really happy with these amps for an indefinite period. I couldn’t image having much desire to listen to anyone else’s system if I had these at home.

This sucker is still in prototype stage, but it’s built like a tank! Power capacitors mounted on the under-side are the size of soup cans—literally.  These look to be over designed and then some, and I mean that in a very good way. These babies are big and very heavy. They are really made for dedicated amp stands.....platforms that sit about 1 foot off the floor. 

Well, I think you can tell that I liked the Axiom amps.....very much.  I haven’t heard anything at RMAF (Rocky Mountain Audio Fest) or at any salon that comes close.  It’s one of two amplifiers that have left a wonderful lasting impression on me. The other ones are Jeff’s (Horning Loudspeaker US Distributor) Audio Note Japan Amplifiers. I can’t think of much higher praise than that, to be in that company. I expect that this amp will be a big success. I’m very, very happy with my choice of Horning Perikles speakers. As we upgraded the system with the Axiom amps, they sounded better and better. 

At its targeted kit price of ($4-5k), it is clearly untouchable. I don’t even have to demo anything else to know that.....and I wouldn’t even be curious to try.  At the targeted finished price (~$10K), it’s still a stellar performer.  I have not heard its’ like anywhere."


Bill  Leebens –  “Hi, Dennis--I finally had the opportunity to audition the Axiom 300B amps at Dr. Bob Hoekstra's home.

Just to review my background: I've been heavily involved in audio since 1970. During the '80's, to my shame, I exchanged many classic American tube amps for Yen, including Western Electric, McIntosh, Marantz, Fisher, Scott, Eico--all the usual suspects. Since that time, I've  owned/used/sold many "modern-day" tube amps--the apogee being an Audio Research tri-amped

system with Tympanis. I've also owned many of the audiophile "holy grail" speaker systems include Western Electric 4181 and 555, Dahlquist DQ-10 and JBL Paragon.

I have also been active in audio circles and the audio industry for many years--my first CES having been in Chicago, 1989. I've also been the sales-manager of VAC (Valve Amplification Company), and am presently working on plans to import a few lines of audio gear.

For what it's worth, during my 25 years in Memphis, Tennessee, I became familiar with the sound of some of the world's most famous recording studios, including Sun, American Sound, Ardent, and Willie Mitchell's Royal Studios.

All this is by way of saying I've been around, I've heard a lot of gear, and I'm not easily impressed.

Now that the basis and context of my opinions have been established, I'll say this: the Axiom is the finest 300B-based amp I've ever heard, the most well-balanced tube amp I've ever heard, and quite possibly one of the best amps of all time. Period.

I am not prone to hyperbole, and those statements have been carefully considered.

The Axiom has none of the tonal or spectral colorations often associated with SETs, and as far as

I can tell, the frequency-response is dead flat. The bass is dynamic and well-damped, and has an engaging tuneful, rhythmic quality. The mids are smooth and detailed, clean and lacking the "warm" coloration we often associate with 300Bs. The high end possesses the airy, effortless quality I associate with live music--and not with "hi-fi". There is no over-emphasis, no spiky, spitty sibilance as with all too many amps--but the highs are there.

Most impressive to me are the Axiom's dynamic capabilities. Most amps--and in particular, most tube amps--have inadequately-stiff and inadequately-isolated power-supplies, so that the current output is modulated by the audio signal. The result is an onslaught of harmonic distortion which many find euphonious, but which I simply find unreal, muddy and lacking in detail. Another annoying byproduct of that aberration is the change in instrument timbre which occurs as volume levels increase.

The Axiom reproduces music as music happens: quickly, without confusing instrumental lines; loud, RIGHT NOW, when the music gets loud; quiet, DEAD quiet, when the music gets quiet. The tonal quality is the same at ppp (pianissimo) and fff (fortissimo). The lack of ANY electrical or mechanical noise allows the Axiom to disappear, and lets the music take over.

Bob's persistence and willingness to explore beyond the existing art have really paid off. The Axiom is an achievement to be proud of, and one which will become known as the benchmark in the world of SET amplifier design--and, indeed, in the world of amplifier design, period.

Well-done, gentlemen!”

In a recent Central Florida Audio Society meeting, held in the 6000 square foot television sound stage studio at WMFE-TV in Orlando, Florida. the Axiom 300B Amplifier was auditioned driving Hedlund Horns with Lowther drivers and Tannoys. Here are some of the comments on the Axiom:

Tom Scata - Speaking of being impressed, there was a beautiful 300B amp, the Axiom.  This amp used no negative feedback and received nothing but praise from everyone who heard it. Hopefully this amp, if the designer is correct, will be out soon in kit form If you’d like to improve the chances of this happening contact Dennis Boyle and tell him you heard the Axiom amp and encourage him to get it into kit form ASAP! 

When combined with the Hedlund/Lowther speakers they worked together to form a disappearing act with nothing but beautiful, glorious music remaining.  This combination had it all, dynamic range, clarity and transparency, midrange to die for, highs that seemed to reach into the heavens without being bright or etched, and a substantial low end that I could more than live with!” 

Author’s name pending - “The highlights of the show were the Chimera Labs Hoekstra Axiom Amplifier prototype and the Lambda Acoustics Unity System. The Axiom 300B Amp is the result of a three-year development project in conjunction with Dennis Boyle, Chimera Labs. The Axiom is an integrated amplifier with three stages (6J5, 6Y6, 300B) exhibiting excellent dynamics and low distortion. The Axiom was demonstrated on several Lowther-type drivers in a pair of Hedlund Horns. After hearing the Axiom , one can conclude that the Axiom is capable of extremely high resolution, detail and dynamics. It can only be hoped that the Chimera Labs will place the Axiom into production as a commercial kit.” 

Paul Butterfield - “I have now had the opportunity to listen to Dr. Bob's Axiom amp in several room environments, and after a recent and extended listening, using music I have recorded, I told Dr. Bob that I wanted to build the Axiom. My background is in location sound recording, and my ears are sensitive to both distortion and transient response in sound reproduction. I would add to the above comments, and say that the Axiom Amplifier, when compared to my studio reference monitor system, couples very low distortion and high transient response in an extraordinary musical presentation.”

Bob is located near Orlando, and he would be happy to schedule an opportunity for interested audio enthusiasts to listen to the prototype. Send me an e-mail for more information.