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While upon delivery Sven had intuitively opted for the midrange-in orientation—it did seem most appropriate to me too—further reflections had me realize that this had all the midrange output travel to the opposing wall for its first reflection. That meant quite a distance. Worse, facing the speakers straight out set up an endless ping pong between the side walls. Toe-in meanwhile produced zigzag reflections meandering down the rear of the room. By the time that energy arrived back at the ear (there are 8 meters of open space behind the speakers) it was sufficiently delayed in time. Whatever bandwidth was reproduced by tweeters and midrange combined—quite a lot with a first-order filter—had the reflected portions arrive outside the 'summed signal' window where the brain still combines arrival times as a singular event. Instead those reflections now registered as discrete echoes to smear the tweeter contributions of the same signal.

What I wanted were faster first reflections. Swapping the speakers was the solution. Completely contrarious to at least my own first assumptions, I now deliberately put the speakers within a CD case length from the sidewalls. I obviously made sure that this distance was equal for the left and right channel. I then toed the speakers in most severely for a nearfield seat location. This gave me a near instantaneous first reflection while the severity of the toe-in placed its ricochet location about halfway between speaker and seat. Bingo. This instantly curbed the overly resonant midband and worked like the proverbial charm. The brain tease was overcoming the belief that such close wall proximity would be disastrous. Au contraire absolut!


I also experimented with different main amplifiers. My 8wpc Yamamoto A-09S 300B amp worked very well but given the general sound's already increased girth, I soon settled on the FirstWatt F5—a bit more incisive and crisp than the sweeter J2 stable mate—as my favorite. This and the Stello Ai500 in bypass mode became the default amplification.

Conclusion: The SLS is a very trick combination of desirable performance attributes which are packaged into a radically narrow while tall profile. Bandwidth for most folks is truly full range. The SLS also is a social animal due to the amazing off-axis response of its flat aluminum tweeters which generously broadens the sweet spot; and by sounding nearly as good from behind which makes these ideal party speakers if set up against opened French doors facing a patio or yard or sitting halfway in an open space where both sides of the room are occupied by an audience.


Driver integration is high which is to say, seamless to the ear. SPL potential even in a sizeable room seems well padded (applying civilized standards). The make-or-break issue really is familiarity with live music. Perversely, this rules out many audiophiles. If one applies highly damped and directional hifi standards of laser-beam holography—not what live music sounds like but exactly what many playback setups are dialed for—then the SLS's pronounced interactions with the room will seem a bit resonant at first.

This adds richness and vibrancy to the sounds. It also animates the space between them as living matter. And that's clearly not the inky-black absence or silence many audiophiles view as the most appropriate canvas on which to superimpose their music. This heightened reverberant action counters what one generally pursues with 'eliminating the room' efforts. Those might include damping/absorption devices, extreme nearfield setups and controlled directivity loudspeakers.


To be clear, the zone of contention here is not the treble. That radiates directly like the norm. Neither is it the bass which always behaves omni at lower frequencies no matter which way the woofer faces. No, the zone of contention is the midband where voices and solo instruments live. Instead of cut and dry, they all sound fluffier, somewhat bigger and enveloped by faint echo. Call it soft reverb and there you are. The extent thereof can be massaged by setup. Whether the effect will seem desirable and more realistic or an artifact which one should eradicate at any cost determines whether you'll love or hate the SLS. It's really that simple.

During the rein of the Mirage speaker brand, the bipolar speaker company experimented with controlled 30% versus 70% weighting between the outputs of their front- and rear-firing drivers. The SLS concept provides no control to alter its direct/ambient balance. Whatever your setup geometry erects by way of reflective surfaces—your only relevant choice is whether the midranges fire inward or outward—determines arrival times and how first and later reflections are spaced and delayed.


Another special feature of the SLS's radiation pattern is being able to link up with the ambient field by sitting in the nearfield. It's not fully immersive surround sound by any stretch but definitely crosses the line between listener over here, sound over there (as though the twain should never mix and mingle).

In matters of tonal balance, the listener has the kind of control ordinarily only afforded by amplified subwoofers with variable outputs and adjustable filters. Unlike most subwoofers however, SLS bass is in stereo and remotely controlled. The remote usefulness should not be underestimated. Sometimes mood and material ask for a slightly goosed LF response. At other times one wants linearity or even tread softly. With the included black box, all that is just a few clicks away - and from the comfort of the seat. And just as iTunes or similar music server access make going back to loading individual CDs seem antediluvian, so does remotely trimmable bass output and compensation contouring ingratiate themselves quickly. Then you wonder how you ever did without.


Less relevant for hard-boiled 'philes perhaps is that the cosmetics of the SLS can go places many conventional box speaker cannot. While the sideways artillery is admittedly unclothed, the tweeters are grilled for both protection and to look properly dressed. I expect significantly lower spousal resistance to letting the SLS have the run of the house or picking a truly prime spot. When everything is said and done, the only good speaker is one you can actually live with, not just dream about or hide in a spare bedroom that's otherwise inappropriate for good sound or social participation.

What sets the SLS apart from most so-called lifestyle speakers is its undeniably serious—one might even say tweaky—focus on audiophile performance. Some quite esoteric stuff here isn't optional or for the few freaks so inclined but standard and built in. How many other performance-oriented speaker models can you name that pay tribute to lifestyle and worry about Bybee purifiers, solid-core silver hookup wiring, low-mass binding posts, Marigo tuning dots and the lot?


Where opinion will diverge is on the suitability of the cheap low-pass filter box. You're obviously free to get serious. After hearing the results 'as is' though, you might just admit—even if only to yourself lest you lose audiophile face—that given its limited bandwidth, it's actually quite sufficient. The final but perhaps most significant bonus of the choices Sven Boenicke made is that with the SLS, one indulges in the kind of generous fluid wet tone which one usually expects from good valves but here already gets with—good but not expensive—transistors. To my way of thinking, that's big. It has SLS also stand for sweetly luscious sound. Having reviewed one of Boenicke's bigger speakers earlier (the W20 SE currently under redevelopment), I feel that this one does more. And while it's certainly far from affordable, it's actually a lot less costly. The quality of the treble, while not as outrageous as the big model's Raal ribbon, nevertheless is a quite close second. I predict we'll see these Tangband units pop up elsewhere soon. As concerns the sidefiring woofers, they clearly energized my room far more evenly than my usual triple-paralleled front-firing array. This is the third time in recent memory that dipole or omni bass had proven to be far less problematic and easier to integrate than conventional solutions.

I'm told that another three review loaner pairs are presently making the rounds. We should soon have additional reports on how the SLS integrates into various listening spaces - and learn whether it ingratiated itself with their owners like my pair did with me. The SLS is a prime specimen of a speaker that captures the feel of a live ambiance better than most conventional speakers I know. That one can move it about without breaking a sweat is merely one of a number of bonuses. In toto, this is a really fine achievement and additionally very artisanal in its employ of solid wood that's been cleverly crafted into a musical instrument by Swiss wood sculptors.


The biggest mistake one is bound to make with the SLS is to not take it serious. "Cute", "different" and "artsy fartsy" are predictable reactions but far too convenient write-offs at that. In fact, this Swiss stick insect is as accomplished a performer as my reference ASI Tango R. The difference is a shift of gestalt, from highly finessed exactitude to a more reverberant live ambiance. While not as radical as Raal's pure omni Eternity—Raal ribbon users Siltech and Crystal Cable have shown their own full-bandwidth omni prototypes—Sven Boenicke's SLS avoids their greater unpredictability of room interactions. But it's still a quite radical speaker that reflects a high degree of original thinking and execution which are in the service of performance rather than difference for difference's sake. I enjoyed my time with the SLS so much—and how it stimulated thoughts about what is realistic sound—that I've acquired the review pair.


I'm far from decided yet on the thought process which the SLS kicked off. It'll take more experimenting and further switching back and forth between more conventional speakers (and the attendant switching in the brain as it were). Getting challenged in matters of perception and surrounding beliefs always is a good thing. Now I'll be able to investigate this intriguing subject at far greater lengths any time I'm so inclined. If I learn anything useful at a later juncture, I'll pen a brief followup...
Quality of packing: Light crate contains both speakers.
Reusability of packing: A few times.
Ease of unpacking/repacking: The speaker is quite lightweight and one of the easiest to move full-range performers I've encountered in a very long time.
Condition of component received: Flawless.
Human interactions: The young owner and designer is a true enthusiast and very responsive.
Pricing: On the face of it quite stiff but once performance enters the equation, perfectly competitive. The looks here really fool you. This is a perfectly serious proposition however, not just a slick industrial design but otherwise sissy.
Final comments & suggestions: By design this speaker demands bi-amping, i.e. two stereo or four mono amps. While theory suggests that it'll work best with sufficient breathing space around it, it's actually tailor-made for both sitting close and standing very close to sidewalls. Because it is so easy to move and quite unobtrusive, it could even lend itself to temporary 'free air' placement in spaces that wouldn't tolerate it permanently. Outside listening sessions then, the SLS would easily store behind a screen, in a closet or tuck behind a tall plant. Moving speakers about usually is no fun. The SLS however is perfectly mobile and could enable applications which are otherwise not possible.
Boenicke website
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