Luminous Audio Axiom III Preamplifier | REVIEW

I am all too guilty of jumping right into the audio science portion of the meal to explain in very detailed ways what I’ve heard, mainly because it’s so ingrained in me from years at my day job. In reviewing the most excellent Luminous Audio Axiom III preamplifier, I’m gonna talk a little more than usual about how it made me feel while I listened to music. I resisted drilling down on the nuts and bolts but simply enjoyed the heck out of my time spent listening to music when it was in my system. In most ways, that’s all you need to know, but I’ll say a little more.

Let’s go back to the 2021 Capital AudioFest. Like most of the attendees and reviewers, I dutifully marched around to pretty much all the rooms in search of gold nuggets. Most of the rooms were populated by very small, sometimes one-person companies, driven by a passion to build a better mousetrap. In these times, it’s not the most difficult thing to make a decent speaker or amplifier. Put a DAC chip in a cool-looking box and call it something like the name of a Greek god or a term from particle physics. Some of these companies actually make stuff that sounds good since we are at the point in technology where it’s almost hard to make something sound bad. The components from the micro-sized (or really ANY size) companies that sound amazing are few and far between. At least that’s been my experience.

Words by Dave McNair

When I was ushered into the Luminous Audio room by my trusted audio show handler, Mr. Eric Franklin Shook, I’ll be honest: it seemed like just another small company that I had sorta heard of – with nice-sounding but unassuming boxes that played music. Eric assured me the Luminous Audio stuff is top-notch and they had a new preamp I should put ears on.

Fast forward a few weeks and a box shows up late in the day to my mastering studio. Oh, it’s that Luminous Audio Axiom III preamp. Okay, I better plug it in and see what’s up.

HOLY MOTHER OF PREAMPS this thing sounds great.

I still had some hi-fi gear that had not been moved to the new house, so the studio house hosted my initial listening. I fed the built-in DAC from my Innuos Zen Mini (streaming Qobuz) straight into the Luminous Audio Axiom III, and then to a pair of Pass Labs XA-200.8s powering my Acora SRC-2 loudspeakers. Detail for days, check. Yet oh so smoooove. Slammin’ bass, check. And that will end my mental check listing…for now.

Tim Stinson of Luminous told me to let it warm up for a day with music playing and keep it on, which is what I did. The next day I listened some more before work. Did it sound better? Maybe, I don’t know, but whatever was happening sounded so good I had to tear myself away that morning to start working.

Back At The (New) Crib with the Luminous Audio Axiom III

After I temporarily moved the mastering studio into the old living room, so that I could do a proper remodel of the standalone garage, a few things became apparent. The Acora SRC-2 is my dream mastering speaker, the living room/hi-fi listening room makes for a fantastic mastering studio, and we’re gonna need another house to live in. I won’t bore y’all with the story, but the new house has a fantastic listening room–by a total stroke of luck.

In the new listening room I have my QLN Prestige Fives set up with a VAC Master Preamplifier and an Audio Hungary Qualiton APX-200 amp. It took me a few weeks to find time and schedule some help to move the TW Acustic Raven LS turntable and the VAC preamp, so I simply listened to CDs at first, then Qobuz streaming off the Zen Mini using either its built-in DAC or my BorderPatrol DAC. The Luminous Audio Axiom III took the place of the VAC pre. The Parasound JC-1+ amps I just reviewed also spent time with the Axiom III.

The Luminous Audio Axiom III looks like a solidly constructed, no-frills, aluminum black box with a blue-tinted LCD screen on the front panel and a single knob for volume. A little plastic remote offers input change, mute, and volume control. I was told by Tim that the remote I received was a cheap generic one because the final, fancier remote was not yet in, but will be shipping with new units. All six inputs are line only, no phono, and unbalanced RCA connections. The dual outputs are also RCA. But ya know what? NONE OF THIS MATTERS.

Why, do you ask? Because the Luminous Audio Axiom III is one of the finest sounding line preamps I’ve ever heard. It’s so good I seriously thought about buying it, but the lack of balanced connections would be a drawback when testing all the review gear that comes and goes outta here.

Luminous Audio Axiom III: Listening And Feeling

One thing that hit me when I first hooked up my system in the new listening space was just how joyful it is to listen to music here. I forgot about making too many observations and simply enjoyed. This is, unfortunately, all too rare for me. It even took days for me to move the speakers around in search of a better spot. Eventually, I got a little more serious and installed custom ceiling clouds that radically improved the focus and imaging. The speaker position got fine-tuned.

Through all of this, I didn’t find myself thinking about “how much better the vinyl will sound.” I simply reveled in the sound of the system when playing digital sources with the Luminous Audio Axiom III in place. At times I mentally noted how incredibly clean and detailed the music sounded through the Axiom III, but I resisted too much in the way of analytics. Okay, I can tell you about the great imaging, subterranean and fast bass response, tight weave of all the sonic textures, but in reality, I simply enjoyed the crap out of listening. I don’t know what the output or input impedance or the signal to noise ratio is for the Axiom III and IDGAF.

Regular readers will know I usually spare no space in detailing exactly all the things that I hear when reviewing a component. This time I almost couldn’t start that process because I was afraid of ruining the experience. That’s how good the Axiom III was for me.

From The Mind of Mike Bettinger

After doing some research, I realized that initially, I had jumped to massively unfounded conclusions about Luminous Audio. For the highly regarded Arion phono preamp reviewed here, Tim of Luminous partnered with audio designer Mike Bettinger. The Axiom III is the latest product in the Luminous/Bettinger collaboration.

Mike has been at the audio design game for more than a minute. He’s been responsible for quite a few well-received products offered from a variety of hi-fi companies such as VPI. He has also received much praise for restoring and improving vintage products from Great American Sound by using his own circuit design mods and parts selection in key areas. Ampzilla anyone?

Mike is a real deal designer who can explain all the intricacies of any part of his circuits. In addition to having a solid working knowledge of circuit design theory, he has the soul of a gear tweaker. Ya know, folks that can sometimes swap out a part or do some minor circuit bending in search of something better sounding than a stock unit. I was in that camp in times past and loved to tinker with my good but budget components in search of affordable gold.

The difference is, Mike knows exactly how the circuit behaves because he designed it! He then travels deep into the land of what is termed voicing. After talking to him and reading his tech document on the Luminous Audio Axiom III, I got the sense that Mr. Bettinger doubles down on voicing like a guy betting his house on a blackjack game in Vegas. Mike told me his wife of many years, Lynn, is an important part of his listening and fine-tuning process partially because she listens in a non-technical, more holistic manner. I don’t know why knowing this gives me lots of warm, fuzzy, feelings, but it does.

Listening with the Luminous Audio Axiom III

As I mentioned before, all my listening sessions with the Luminous Audio Axiom III used digital sources.

Tears For Fears, The Tipping Point
I read an interview with Curt Smith and Roland Orzabal in a recent issue of Tape Op magazine, so I was curious to hear this when it dropped. Maybe not groundbreaking, but worth a listen. The Luminous Audio Axiom III allowed me to take in this well-done but typically dense, compressed and modern production without really being too put off. It’s easy for uber-hi-fi recordings to show off a component. When I play an album like this one and all the good stuff emerges, that’s when I know something special is happening.

XTC, English Settlement
This one continues to be in my current rotation. The Axiom III rendered these jams with loads of detail but never at the expense of a fluid feeling of listenability. The entire low end (which is mighty on a lot of this album) was massive without feeling decoupled from the rest of the music. Major points for the sheer sense of slam and low-end extension.

Punch Brothers, Phosphorescent Blues
Like English Settlement, this is another one where I regularly enjoy listening to the vinyl so I tend to use the digital version if I need to evaluate a DAC, or in this case a line stage. With the Luminous Audio Axiom III, I heard the difference in Chris Thile’s lead vocal timbre on different tunes–owing to whether it was sung live while playing mandolin or overdubbed. There is a telltale comb filtering to the midrange that happens from when the mandolin microphone is also “hearing” the vocal. I could be completely wrong about this but regardless, the Axiom III pointed out differences in vocal timbre between “Familiarity” and “Julip” that I hadn’t previously registered. The Axiom III beautifully fleshed out all the gorgeous and sometimes delicate tones on the album.

Dire Straits, Love Over Gold
I know, I know. At this point, Dire Straits is almost criminally overused, over-cited, and just generally worn into the ground in the audiophile community. I used to kind of like this album. Whatever. I’m using it yet again because I think it’s still a common reference point for a lot of audiophiles. And it still sounds great, even if it exhibits a lot of energy above 10K. That hyper-reality brightness, however, gives me an instant reading on how a component treats a recording with a lot of extra air. Additionally, Love Over Gold has quite a wide dynamic swing, something in short supply these days. The Luminous Audio Axiom III passed the Dire Straits test with flying colors. The Axiom III not only did not exacerbate the top end, it kept things listenable while allowing me to hear the slightly lean harmonic structure of this recording borne of its early ‘80s mixed-on-an-SSL console, sonic signature. Early Solid State Logic consoles were revolutionary in many ways, but dry as melba toast.

I want to point out again that I simply listened without the critical part of the equation. Linda and I played lots of Queen, Todd Rundgren, Tom Petty, The Police, Beatles, Beach Boys and more. Some nights it was solo listening for me with lots of jazz, world music, and a smattering of classical. I didn’t think much about the Luminous Audio Axiom III or the rest of the system. At one point, however, I swapped out the Axiom III for my reference preamp, a VAC Master Preamplifier.

It was a bit of a shocker in that the VAC had a beautiful top to bottom coherence and beauty coupled to a slightly warmer feel to the low midrange but, the Axiom III MORE than held its own by having a greater sense of detail without any edge or harshness. With the Parasound JC 1+ amps in the system, I got even more clear, clean detail, and low-end slam.

The Tech Nerd Section

The Axiom IIIs extreme detail along with its phenomenal low-level resolution and effortless display of dynamic contrasts is obviously a result of Mr. Bettinger’s carefully chosen design and execution. I’ll quote a few sections from the design notes I got from Mike. On the Axiom III’s design focus:

“The Axiom III was designed within the same constraints and technologies available to all designers.

“The Axiom III’s input stage is a single ended, modified folded cascoded dual differential circuit followed by a series cascoded Class-A buffer stage. The current sources for biasing are also cascoded, based on engineering shared by Nelson Pass years ago. Our approach to the circuitry focuses first on the circuit topology, for which we have ferreted out our favorite circuit building blocks over many years and much listening. Next our efforts focus on the critical electrical environment in which the circuitry operates. Addressing the subtle interactions between the various stages of the design provides many benefits in the dynamic response and resolution of this classic circuit topology.”

On voicing the Axiom III:

“Experimentation has proven there are substantial benefits gained by dialing in the active device biasing. At times it is like choosing the best optical lenses and painstakingly focusing them for image clarity. Starting our efforts with the biasing of the J-FET based input stage – more specifically the J-FETS, as they are the gatekeepers for how much of the fragile musical signal gets into the preamp. This stage’s function is to raise the level of the minute signal entering the preamp with as little damage as possible, while minimizing the interaction with the source components feeding it.

“The input stage amplifies the musical signal to a level that makes it is easier for subsequent stages to process accurately. Because of their high sensitivity and input impedance, J-FETS, the solid-state equivalent of a tube, are ideal devices for this application considering they were routinely used as input devices in analog radio receivers, where they accurately detected and processed micro-volt level radio signals from the antennas.

“J-FETs also have a wider dynamic range than similar small signal bipolar transistors – but a careful balance must be made between the choice of device parameters and the voltage and currents chosen to bias them to extract the best performance from them. I focus my biasing efforts at the lowest signal levels rather than the tuning for performance at their maximum output levels. The goal is to operate them in their sweet spot for sensitivity and gain. Properly biased, they are capable of incredible resolution of the finest details hidden deep in our analog sources.

“Once the input signal is amplified by the input/voltage amp stage, the focus shifts to the output buffer stage. This must be easy for the input stage to drive while developing enough output current to easily drive both the reactive feedback network and the wide variety of reactive loads that connect the preamp output to the outside world!

“The device of choice for this application is carefully selected bipolar transistors which do a great job, to my ears, of handling the higher Class-A currents needed to drive the output load. Additionally, both input and buffer stages utilize cascode circuits to improve the gain and isolation from the effects of power supply disturbances.

“The circuit layout is then optimized. The circuit layout focuses on minimizing interactions between the various functions of the circuitry and minimizing unintended feedback paths that can occur either through layout choices or by coupling back through the power supplies and ground references. When carefully executed, this aspect of the design promotes clarity and a lack of congestion on complex passages and effortlessness to the dynamic flow to the music.

“Minimizing unintended signal coupling in the layout (seen as feedback or subtle filters by the circuit) also provides outstanding circuit stability and a dramatic reduction in IM distortion. This is heard as a purity on vocals and a sorting out of the musical layers, heard easily on multiple vocals and strings and is immediately obvious on cherished recordings. Decays and room ambience seem to extend forever.

“Third on the design focus list are the power supplies, which are by no means third in importance. I design supplies with a naturally low source impedance and low natural damping over artificially stiffened regulated supplies, preferring instead to embellish this performance with zero gain voltage stabilization to minimize operating point drift. I also design for minimum interactions between the positive and negative halves of the supplies, which have separate functions and should not mingle.

“Power supply voltages are chosen with device dissipation and circuit stability as priorities. While all stages run high class-A biasing, stiff power supplies and relatively modest device dissipations provide a sense of low dynamic current noise, often heard as a texture or haze that subtly masks fragile decays and the sense of air. Another benefit to this approach is an inherent circuit stability, requiring only minimal circuit compensation, that exhibits a freedom from parasitics on dynamic peaks.

“In its entirety, the design provides a solid low frequency foundation to the music with extension and lack of bloat to the low frequencies, coupled with a sense of nuance and articulation creating a natural, realistic foundation for the musical presentation, especially with source components that can supply the appropriately refined musical signal.”

Luminous Audio Axiom III: Final Thoughts

By now you should be getting the message that I loved listening to music with the Luminous Audio Axiom III in my system.

The Axiom III retails for $7,995. This is not an insignificant amount for a lot of folks. Yet the Axiom III sonically rivals preamps costing five times and up, more. No, it doesn’t have any bells and whistles. No phono or built-in DAC. All unbalanced ins and outs. A solid and hefty feeling chassis, but without any real bling factor.

What you get here though is pure, unadulterated, sonic bliss. The kind of sonic excellence that allowed me to intensely enjoy anything I cared to listen to. Yes, it checks all the audiophile boxes in terms of sonic performance buzzwords but it gave me more than that. It allowed me to feel.

And that’s priceless. Highly recommended.