Founded in Brilon, Germany, a small town some 90 miles north of Frankfurt, Audio Physic has for 30 years been earning accolades for producing high-quality, highly resolving loudspeakers under the slogan “No loss of fine detail.” More recently, AP’s reputation for quality, performance, and unique applications of loudspeaker design and materials has generated a lot of buzz on both sides of the pond -- in fact, their provocative products are one of the reasons I became a reviewer. So when I had the opportunity to review Audio Physics’ latest loudspeaker, the Codex, I jumped.

In the box

My review samples of the Codex arrived literally moments after reading associate editor Roger Kanno’s review of Audio Physics’ recently revised Avanti loudspeaker. Winner of a Reviewers’ Choice award, the Avanti shares several design principles with two of its more complex and expensive brethren, the Codex ($14,995 USD/pair) and the forthcoming Aventera III ($22,995/pair). Had Roger’s review not already given me a glimpse into the multitude of technical tricks the Codex had in store, I’d have been lost as to how the Codex is a true four-way, four-driver, bass-reflex design -- only a vertical array (from top) of midrange-bass, tweeter, and midrange drivers is visible from the outside, with no hint of a fourth driver or port.

Audio Physic Codex

Out of their ample packaging, the appearance of the sharply raked-back Codex is as alluring as it is imposing. Weighing 97 pounds and measuring a tallish 47"H x 8"W x 14.5"D, the Codex is available in four standard finishes: Walnut, Cherry, and Ebony wood veneers, and Glass Black High Gloss. For an extra $500/pair, you can choose from among Black Ebony, Rosewood, or one of five additional Glass finishes: White, White Aluminum, Grey-Brown, Maranello Red, and Purple Red. Each Codex comes with a grillecloth and a dark-tinted glass surround for the three visible drivers, both coverings magnetically attached. After a brief comparison, I found the glass to be most appealing, visually and audibly, despite offering somewhat less protection.

Audio Physic Codex

Each Codex has four drivers: a 1.75” Hyper Holographic Cone Tweeter (HHCTIII), a 5.9” HHCMIII midrange driver, a 7” midrange-bass driver designed solely for the Codex -- all three with cones of ceramic-coated aluminum -- and a long-stroke subwoofer with a 10.2” cone of air-dried paper. Both the 7” cone and the 10.2” subwoofer cleverly concealed below it are derivatives of drivers currently manufactured by Wavecor, and include Wavecor’s Balanced Drive technology. Each has been modified to meet AP’s specifications for the Codex: operating bandwidths of 100-300Hz for the midrange-bass and 28-100Hz for the subwoofer. (The speaker’s overall specified frequency range is 28Hz-40kHz.) Balanced Drive optimizes the symmetry of the forces induced in the voice-coil. The idea is that with these forces balanced, even-order harmonic distortion can be dramatically reduced. The 7” midrange-woofer and 10.2” sub rely on support structures of die-cast aluminum, and exclusive formers of black glass fibers to keep their respective 1.5” and 2” voice-coils in line. In addition, both drivers have vented center poles designed to aid in overall cooling. About the only thing differentiating the 7” from the 10.2” cone, other than size, is their construction; the midrange-woofer is made of ceramic-coated aluminum, the subwoofer of semi-air-dried paper. Each driver is fed its part of the signal by its own dedicated crossover wired with AudioQuest cables.


The upper-midrange driver, first implemented in the Avanti, has a much wider bandpass of 300-2800Hz, and a very rigid cone of pre-stressed aluminum, to avoid the ringing typical of metal cones. This cone, and its surround, centering device, and voice-coil, all function within an innovative dual-basket architecture. The moving parts are mounted on a plastic inner basket of minimal resonance, supported by an outer basket of die-cast aluminum that dissipates heat through integral heatsinks. According to AP, because aluminum dissipates heat better than plastic, the moving parts can be driven to higher loads while preventing deformation of the cone. Dual neodymium magnets comprise the motor system, while the voice-coil, as in the other drivers, is supported by a former of black glass fibers. The alignment of the overall assemblage is managed not only by the inner damping basket, but also by a solid phase plug of anodized aluminum directly coupled to the beefy outer basket.


The Codex shares its 1.75” HHCTIII tweeter with almost all other Audio Physic speakers, from the new Step Plus ($2595/pair) all the way up to the top dog, the Cardeas 30 LJE ($45,995/pair). Capable of reproducing frequencies up to 40kHz, the cone of the tweeter is cleverly concealed behind a dustcap that closely resembles that of a dome tweeter. The tweeter is the only driver in the Codex to receive its signals via a proprietary interconnect, and, like the three other drivers, is fed signals through its own dedicated crossover. When I asked Roy Feldstein, chief technical officer for VANA, Ltd., AP’s North American distributor, why four crossovers per speaker rather than two or even one, he said that the idea was to avoid electrical and mechanical interference between filters. Each crossover is mounted directly behind its driver, and comprises high-quality inductors and resistors, and capacitors specially made by Clarity Cap. The more substantial crossover dedicated to the subwoofer is coupled directly to the top panel of the concealed subwoofer enclosure.

Audio Physic Codex

In a specialized factory not far from AP’s headquarters in Brilon, the Codex cabinets are built of 7/8”-thick slabs of MDF. Bonded to the cabinet’s core structure are the top, front, and side panels: glass from a supplier not far from the factory, or finished panels of 1/4”-veneered MDF made in Italy. This approach is said not only to add rigidity but also make the cabinets more inert. The core cabinet is heavily reinforced with braces of, again, 7/8”-thick MDF, and includes separate sealed chambers for the tweeter and two midrange drivers. The subwoofer, housed in its own sealed box, fires into nearly 75% of the cabinet’s internal volume, its output eventually venting through an opening in the speaker’s base. This port and several other key areas in the Codex’s interior are damped with carefully positioned pieces of rigid yet ultraporous ceramic foam that is about 85% air. This unique damping material is said to provide a multitude of advantages; e.g., simultaneously serving as both damping and bracing, having minimal impact on internal volume, and acting as a resonance chamber within a large opening in the speaker’s base. It was explained to me that, as volume levels and the resultant air pressure inside the cabinet increase, the foam becomes more resistive, essentially acting as a resonance outlet. AP claims that this makes possible more precise reproduction of bass and, in extreme conditions, helps prevent chuffing.

Audio Physic Codex

Supporting each Codex is yet another engineering trick: Audio Physics’ VCFII M8 Vibration Control Feet. These ingenious pucks combine both string and magnetic suspension; the former resemble very small tennis rackets. The result is a fully suspended rather than a coupled speaker, which, I can attest, improves image specificity without affecting bass reproduction. Also noteworthy are AP’s unique Vibration Control Terminals with WBT NextGen connectors, coupled to a solid-aluminum terminal plate mechanically isolated from the enclosure by a rubber gasket.


Sometimes, it’s difficult to verbally describe the sound of an audio component. Luckily, in my first few hours of critical listening, I was able to nail down the Codex’s character in three words: holographic, resolute, and articulate. All three of these characteristics were clearly audible when I listened to a familiar favorite, Patricia Barber’s Café Blue (16-bit/44.1kHz FLAC, Premonition/Blue Note). With “What a Shame,” I was immediately struck by how open, wide, and holographic the sound was. The Codexes had an uncanny way of extending the boundaries of my room in every direction, but even more impressive and alluring was how well they portrayed each instrument on those grand stages. Describing the sound of a speaker as holographic may imply that the sound is a bit wispy, as this is a common quality associated with this adjective, but that wasn’t the case here. Part of the allure of the Codex’s sound was how it combined the holographic presentation of aural images with the solidity required to let them sound real. Barber’s voice, locked at center stage about 3’ behind the plane described by the speakers’ front baffles, “appeared” with a density and promptness of response that made the illusion of a real singer standing between the speakers pop with realism. She sounded solid enough on stage that I got a clear and distinct impression of the space behind her.


Later, in “Mourning Grace,” Mark Walker’s drums revealed similar senses of body and dynamic athleticism, complemented by satisfying levels of slam. The sounds of his sticks hitting drum skins, rapidly battling from each side of the soundstage, were cleanly delineated against Michael Arnopol’s double bass. The dynamic flare following each splash of the cymbal was easily appreciated, as was the decaying shimmer of each hit.

I turned up the volume more than a few times here, trying to find the limit past which I couldn’t push the Codex without its sound getting compressed or aggressive. That limit proved to be beyond any level I was comfortable driving review samples to, but in my failed attempt I learned something: Driven hard, the Codex had a badass bottom end. Unfortunately, this discovery also led to one of my few gripes about the speaker: When I drove the Codex to anything less than moderate volume levels, its bass energy dropped off much more than did its midrange and HF output.

Audio Physic Codex

Here’s what I mean by that: Overall, the Codex was a convincing loudspeaker, unfailingly communicating the subtle nuances and microlevel details of whatever recording I asked it to reproduce, and maintaining this level of resolution regardless of volume, type of music or recording, or amplification. At ambient levels, most passive loudspeakers tend to struggle to reproduce frequencies below 100Hz in a way that keeps them in balance with frequencies above that threshold because, all else being equal, lower frequencies are simply harder to hear at these levels -- rather than a fault in the speaker or its design, it’s just how human hearing works. It’s been my experience that this problem tends to dissolve once the volume rises above ambient level -- which, with my Simaudio Moon Evolution P-8 preamplifier and Moon Evolution W-7M monoblocks, is typically around the 20% mark. At that point, I can usually begin to hear the depths to which a speaker was designed to extend. With the Audio Physic Codex, I found that the volume setting needed to be a bit higher before I could hear the frequencies at or near its specified lower limit of 28Hz. In fact, it wasn’t until I’d turned up the P-8’s volume to 35% that the Codexes began to sound properly balanced -- which surprised me, considering that this speaker’s claimed sensitivity is 89dB. Some may consider this a nonissue -- most people don’t drop 15 grand on a pair of speakers to listen to them at ambient levels -- but that argument has a flip side: At $14,995/pair, a speaker should sound balanced at almost all volume levels; if it doesn’t, it’s my job to point out any such inconsistency, however minor.

With the Simaudio P-8’s volume set at around 55%, I cued up “Hold On,” from Eric Bibb’s Live à FIP (16/44.1 FLAC, DixieFrog). The track opens with Bibb playing his acoustic guitar, accompanied by Trevor Hutchinson's wonderfully recorded double bass. Expectedly, Bibb’s voice popped at center stage with the solidity, texture, and three-dimensionality I was quickly growing to expect from the Codexes, but what really caught my ear -- and what immediately drew me into this track -- were the depth and body of Hutchinson’s bass. I could feel the lower notes in the floor as I tried to find fault with how the Codexes reproduced each note. I found little to complain about. Each note was conveyed with rewarding depth and accurate tonality. Bass bloat, boom, and tubbiness were nowhere to be heard, even as I pushed the volume past 70%. The Codexes reproduced each of Hutchinson’s notes with controlled precision and balance, and surprisingly more detail than I would have expected from a passive speaker with a concealed 10.2” bass driver. As the track continues and Bibb and Hutchinson continue to occupy center stage, they’re joined by Staffan Astner on electric guitar and Larry Crockett on drums. With the band at full boil, the Codexes delineated and made easy for me to appreciate each instrument on stage by convincingly portraying the spaces between them. Everything and everyone was appropriately layered, with no loss of such fine details as the decay of Crockett’s wood blocks or the splash of his cymbals’ brass.

Audio Physic Codex

Later, enjoying Jeff Beck’s cover of Screamin’ Jay Hawkins’s “I Put a Spell on You,” from Beck’s Emotion and Commotion, with Joss Stone singing (16/44.1 FLAC, Atco), I was again treated to a larger-than-life soundstage. The transparency with which the Codexes portrayed Vinnie Colaiuta’s snare drum approached what I typically expect from my reference Rockport Technologies Atrias ($21,500/pair, discontinued), and the breath powering Stone’s seductive singing was unmistakable. Again, the Codexes fully laid bare the sheer punch of Chris Bruce’s bass, and when Beck’s electric guitar rips onto center stage, it, too, sounded larger than life, until it receded into the background, awaiting another chorus through which to erupt.

Audio Physic Codex

I went on to enjoy “Serene,” an instrumental that’s much too easy to get lost in. I leaned back, letting my foot tap to Bruce’s rhythmic bass, and began to focus on each element onstage. Beck’s electric guitar is clearly the focal point of this track, and the Codexes did a commendable job of balancing the instrument’s dynamism and tonality. E-guitars can sometimes sound a bit screechy through speakers as detailed as the Codex, but I heard none of that. What I heard were smooth, dense, vibrant notes complemented by Bruce’s unfailing bass and Jason Rebello’s melodic keyboards. About two-thirds of the way into the track, behind Colaiuta's drums and fast, transient brass, I was treated to an airy if somewhat recessed tambourine. It was easy to discern the different types of brass at play. Holographic, resolute, and articulate? The Audio Physic Codex was all three.


Just before the Audio Physic Codex, I reviewed Monitor Audio’s Platinum II PL300 II. Priced just $500 below the Codex, the PL300 II proved to be an outstanding loudspeaker.

Before describing the different characters of these speakers, it’s worth noting that, on paper, they have nothing in common other than the fact that both are bass-reflex designs. I won’t get into the mechanics of how the speakers diverge technically; for that, you’ll have to read my review of the PL300 II as well. Instead, here I’ll focus on their audible differences, of which there are many.

The largest difference, by far, was in how these two floorstanders cast aural images. Both draw tightly focused, richly colored, solidly grounded sonic pictures. The Codexes projected images closer to me, front-row style, which made their overall sound more vibrant than the PL300 IIs’, and seemingly more detailed. The Monitors sound more laid-back and relaxed, their images farther back behind their baffles, as if I’m sitting in Row 6. Interestingly, I found that the two speakers presented similar levels of microdetail, despite the perception of added detail from the Codexes’ more vibrant sound. The Codexes’ extra vibrancy did give it the edge in dynamic authority; heavy thwacks to the skins of Chris Layton’s drums in “Tin Pan Alley,” from Stevie Ray Vaughan’s Texas Flood (16/44.1 FLAC, Epic/Legacy), popped into the room with a bit more impact and scale than through the PL300 IIs. The Codexes also painted the images of male and female singers a hint brighter in color, again creating an illusion of easier-to-discern inner detail. While close and repeated comparisons revealed these speakers to be equally transparent, I preferred the slightly more organic sound of the PL300 II’s midrange, particularly when listening to music at spirited levels.

Audio Physic Codex

Evaluating the differences in these speakers’ bass qualities was an interesting exercise -- these two manufacturers take completely different approaches to producing bass, and the differences were clearly evident in what I heard. I listened to all kinds of music, ranging from jazz to electronic to rock, and at low levels, regardless of the recording, the Monitor Platinum II PL300 IIs offered better-defined, more audible bass. At moderate levels, the playing field was leveled: the Codexes produced deep, articulate, impactful bass notes. While the overall volume of bass at the same volume level was greater through the Monitors, the balance, tonality, and quality of bass were slightly better through Audio Physics -- the Monitors consistently exhibited a bit of lower-midbass emphasis, a wisp of tubbiness in the bottom end. This added midbass bloom increased as the volume increased, but it was likely the result of the PL300 II being a bit too much speaker for my 21’L x 12’W room. By contrast, the Codexes proved a perfect fit for my space, exhibiting excellent control of lower notes, particularly as I increased the volume level. Considering that the PL300 II uses twice the surface area to breathe bass into my room, the quantity and quality of bass generated by the Codex was admirable.


If I’ve learned one thing from writing this review, it’s that Audio Physic speakers are unique in both design and execution. The Codex has not only opened my ears to a speaker manufacturer I was only moderately familiar with, they’ve opened my eyes to some genuinely clever design approaches I can only hope will be adopted by other manufacturers.


The Codex is a very well built, beautifully finished loudspeaker based on sound engineering principles and comprising quality components. I found it to be a very revealing speaker that was resolute in its rock-solid bass performance, and convincing in its articulate reproduction of highly focused, vibrantly colored, holographic aural images. In the Codex, Audio Physic has produced something special. I highly recommend that anyone willing to spend up to $15,000 on a pair of speakers give it a serious listen.

. . . Aron Garrecht

Associated Equipment

  • Speakers -- Monitor Audio Platinum II PL300 II, Rockport Technologies Atria
  • Subwoofers -- JL Audio Fathom f112 (2)
  • Amplifiers -- Parasound Halo A 51 (five-channel), Simaudio Moon Evolution W-7M (monoblocks)
  • Preamplifiers -- Anthem AVM 60, Simaudio Moon Evolution P-8
  • Sources -- Oppo Digital BDP-103 universal BD player, Dell E7440 Ultrabook laptop computer running Windows 10, JRiver Media Center 20
  • Digital-to-analog converter -- Wadia di322
  • Cables -- Clarus Crimson S/PDIF and USB interconnects; Kimber Kable Select KS-6063 speaker cables; Cardas Clear Blue Beyond power cords
  • Power conditioner -- Torus Power AVR2 20A

Audio Physic Codex Loudspeakers
Price: $14,995 USD per pair.
Warranty: Ten years parts and labor.

Audio Physic
Almerfeldweg 38
59929 Brilon
Phone: +49 2961-961-70
Fax: +49 2961-516-40


North American distributor:
VANA, Ltd.
2845 Middle Country Road
Lake Grove, NY 11755
Phone: (631) 246-4412