Given all this, one might expect the Sonja XV to represent yet another evolutionary step along the path, and in one sense it is, but in an overarching sense it is also much more than that: namely, a step up in performance so dramatic that it simply stops listeners in their tracks and gently but insistently compels their rapt attention. The funny part is that the speaker seems to have this effect not only on first-time Sonja XV listeners, like me, but also on veteran Sonja XV listeners like Dick Diamond, Bill Parish, and Joe Kubala, co-founder of Kubala-Sosna Research (the firm whose cables were used exclusively in the demonstration system).
Some common reactions to the speaker might be, for example, eyes growing wide as the Sonja XV explicates familiar musical passages in an exceptionally lucid way, or deep chortles as the Sonja XV exposes unexpected moments of vivid realism in well-recorded tracks, or—at the very best three-dimensional moments—blurted expressions such as, “How is that even possible?” When I say the Sonja XV offers an extremely compelling listen, I am—believe it or not—exercising my very best American imitation of traditional British reserve and understatement. The tricky part is that the Sonja XV is pulling just as hard in the opposite direction—evoking almost shameless, gushing expressions of musical awe, wonder, and delight. It’s just that kind of loudspeaker.
The Sonja XV consists of two large towers per channel. The main tower features a two-way, three-driver tweeter/midrange module at the top, a three-driver mid-bass module in the middle, and a single-driver bass module down at floor level. Then, standing slightly behind and to the side of the main XV tower is a second tower that is focused purely on low bass and that consists of three more bass modules that are different in shape, but equal in enclosed volume, to the bass module used in the main tower. Starting at the bottom of the frequency range and working upward, the crossover points used in the Sonja XV are placed at 65 Hz, 337 Hz, and 1.75 kHz.
Most of the technologies used in the speakers have, with two key exceptions, been seen in past YG Acoustics designs. Thus, the six modules that comprise each Sonja XV feature cabinets whose panels are precision machined from solid slabs of aircraft-grade aluminium, then treated to an exquisite black anodised finish. Cabinet panels are joined using aircraft-style ‘pressurised assembly’, which is a subtle technique that deliberately pre-stresses panel-to-panel joints in a way that eliminates both vibration and air leaks and that makes for a cabinet that is exceptionally rigid and stays that way over time. On the cabinet interiors, YG uses its proprietary ‘FocusedElimination™‘ technology to reduce resonance while at the same time minimising mechanical or friction losses (the design is said to provide the critical damping advantages of a sealed enclosure with the freedom-of-driver motion benefits of a vented enclosure).
Crossover boards are of ultra heavy-duty construction, so that the board’s circuit traces are not ‘printed’, but rather machined into the ultra-thick pure copper layers on the face sides of each board. Many components used in the crossovers are top-shelf units from manufacturers such as Mundorf, but in certain critical areas—most notably large, in-the-signal path inductors—YG chooses to make its own components. Thus, the firm builds ‘ToroAir™’ CNC-wound toroidal air-core inductors for its mid-range and high-frequency crossover, and—in a first for the Sonja XV—uses its own all-new ‘ViseCoil™’ CNC-wound low-frequency inductors, which are encased in beefy, vise-like milled enclosures said to “eliminate vibration and tighten tolerances.” YG provide a brief video showing how its ViseCoil inductors dramatically outperform even the most costly of available third-party inductors.
The Sonja XV’s bass, mid-bass, and midrange drivers feature the firm’s signature ‘BilletCore™’ driver technology, where each driver diaphragm is precision machined from a thick, blank billet of aircraft-grade aluminium. According to YG’s Yoav Geva, this construction technique, which at first blush seems almost gratuitously extreme, actually yields diaphragms whose dimensions are more tightly controlled and whose molecular structure is more relaxed and free from incipient microscopic stress cracks or ‘crazing’ structures than diaphragms made from metal stampings or from composite materials. Thus, there’s real, serious method to the BilletCore ‘madness’, with the benefit that the drivers performs better when first manufactured and maintain as-new performance indefinitely over time (other diaphragm construction methods, says YG, are prone to gradual performance degradation over).
The tweeter user in the Sonja XV is entirely new and might be the single greatest contributor to the speaker’s overall performance. YG calls its new driver a ‘BilletDome™’ tweeter, which is perhaps a bit misleading in that the tweeter is actually a hybrid creation using a resonance-free fabric dome diaphragm reinforced from the back side by a minimalist, precision machined, ultra lightweight (30 milligram) aluminium support frame—or ‘airframe’, as YG would have it. The intent is that the BilletDome tweeter will have the smooth, non-ringing character for which fabric soft-dome tweeters are known, yet will also have the stiffness and strength to survive ultra high-G-force acceleration. (YG points out that real-world high frequency musical material sometimes requires acceleration of well over 1000+ Gs.) YG claims that its new tweeter thus resolves the “age-old debate of hard versus soft (domes), by combining the best of both.” Like other YG tweeters, the BilletDome tweeter uses a motor magnet system created through the firm’s ‘ForgeCore™’ system—an approach where the magnet assembly is CNC machined to include what YG calls “sophisticated 3D geometries” said to reduce distortion and foster a sonic sense of smoothness and ease.
Finally, like all YG speakers, the Sonja XV was designed through use of proprietary Yoav Geva-designed CAD software, which YG calls ‘DualCoherent™’ technology, whose defining characteristic is that it allows simultaneous optimisation of both the loudspeaker’s frequency and phase response. Accordingly, YG specifies that the Sonja XV offers frequency response from below 20 Hz to above 40 kHz, with frequency response deviations of ± 1dB “in the audible band” and ± 5° relative phase “throughout the entire overlap”.
No matter how impressive this technical description might sound, replete as it is with its many trademarked names for the various technologies incorporated in the design, nothing can fully prepare the listener for actually hearing the Sonja XV in play.
Several qualities stand out. First, as expected, the speaker offers exceptionally even and neutral tonal balance with extremely wide-range frequency response. Second, given the 10 drivers sharing the workload per channel, the Sonja XV exhibits a quality of relaxed dynamic ease, no matter how demanding the musical material at hand may be and no matter how loudly (within reason and the natural desire to avoid volume-induced hearing damage) you might choose to play the speaker. Third, the speaker offer better main tower-to-woofer tower integration than any competing multi-tower design I have ever heard. Even when listening intently for any tower-to-tower discrepancies or discontinuities, I found there simply weren’t any. In fact, if anything the bass response of the Sonja XV sounded noticeably quicker, deeper, and better defined than in even the finest single-tower speakers I’ve heard in the past.
But finally we come to the three qualities that set the Sonja XV apart from other YG models (and from many if not most competitors, as well): extreme resolution, extreme effortlessness and smoothness (especially treble smoothness), and uncanny three-dimensionality. As I mentioned earlier, you can hear a gradual evolutionary increase in resolution as you work your way upward through YG’s model range, but with the Sonja XV resolution has taken a more than merely incremental step upward. I think this may well have to do with spreading the workload evenly across a larger number of drivers—most notably in the bass and mid-bass region—so no individual driver has to work as hard as in YG’s smaller models. The result is that extremely low level textural and transient details in music are suddenly resolved with disarming ease. It’s almost become trite to say, “Speaker XYZ reveals details I never heard before in my favourite recordings,” though this is exactly what the Sonja XV does. But what’s profoundly significant is that the Sonja XV offers these new sonic revelations across the entire audio spectrum and at such a high level that recordings seem—this is no exaggeration—quite literally transformed, essentially becoming markedly better versions of their previous selves.
Now normally declarations that a given speaker dramatically improves resolution might be followed by a consumer warning of sorts, to the effect that, “with all this newfound resolution comes a certain unforgiving amount of edginess, stridency, and pain.” This emphatically is not the case with the Sonja XV; one of its most impressive qualities, and one that is terrifically beneficial in terms of musical enjoyment, is that its impressive gains in terms of resolution are matched step-for-step with equally impressive gains in overall smoothness—especially treble smoothness. This is quite extraordinary, because it means that through the Sonja XV high frequency details simply happen—with no histrionics, no hey-look-at-me spotlighting, no edginess, and no glare. You enjoy all the high frequency information you might ever want, with no heightened stress levels or pain factor whatsoever. Well done, YG!
Put all these qualities together and the Sonja XV stands as a very big speaker that offers—quite surprisingly—better than state-of-the-art mini-monitor-grade imaging and three dimensionality, but with the ability to scale upward and downward in its presentation to match the scope of the musical material at hand. Put on something big and powerful (e.g., O’Connor’s Fanfare for the Volunteer) and the Sonja XV will transport you a to very large acoustic space filled with a dramatic orchestral performance. But put on something smaller in scale (e.g., Jen Chapin’s rendition of Stevie Wonder’s ‘Big Brother’ from ReVisions), and the Sonja XV ‘zooms in’, sonically speaking, to give an intimate, up-close-and-personal view of the vocalist and her highly simpatico trio at work.
Unlike many physically imposing speaker systems, then, the Sonja XV can play big, or small, or anything in between. All things considered, the performance of the Sonja XV is not just different in degree from the other models in YG’s range; it is different in kind because it steps up its ability to reproduce recorded music not just by a click or two, but by many clicks and all at once. The sonic and emotional effect is as deeply moving as it is enchanting.
The reality is that, absent an unexpected winning lottery ticket, I will never be able to own the Sonja XV, yet I am very glad to have heard it. In retrospect, my listening session with the Sonja XV at GT Audio & Video has come to represent a benchmark experience for me—a high water mark in terms of experiencing what’s possible when everything comes together to create moment of musical magic. It’s an experience I hope many Hi-Fi+ reader might also be able to enjoy. If you have a chance to audition YG Acoustics’ Sonja XV, by all means take it.
About the System:
The demonstration system for the Sonja XV consisted of a suite of Audionet monoblock amplifiers and front end-components, analogue audio via a Kronos Pro/Black Beauty turntable tonearm system fitted with an Airtight Opus 1 phono cartridge, digital audio (at CD and higher resolution levels) fed from a Roon server, with Kubala-Sosna Elation cables throughout. My understanding is that Bill Parish, Dick Diamond, and Joe Kubala joined forces to set up and dial-in the system, prompting Kubala to exclaim, “C’est magnifique, n’est ce pas?” Indeed it was and is.
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