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Naturally, any open-baffle dipole creates significant figure-8 cancellations from out-of-phase rear radiations wrapping around the baffle. Those effects operate at wavelengths longer than the baffles are wide. Make no mistake, this speaker does produce prodigious LF energy coming off the woofer cones. But a substantial portion of it vanishes in thin air before reaching the listener. Without for all practical intents and purposes a front wall, the Veena in my 13-meter long room had noticeably less output below 35Hz than my monopole Tango R reference. Yet stepping behind the speaker proved the woofers to be working hard indeed. Hence the woofer amp includes an inbuilt 'rev limiter'. It avoids possible overdrive. (There's also a strategic notch filter on the Lowthers to flatten their ca. 4kHz peak). In his room, Claus Jäckle reports measurable flat bass extension to 30Hz. Obviously, this will vary in unpredictable ways from space to space. Mine swallowed up some extension to miss the good-to-20Hz definition. Still, the reach of Renaud Garcia-Fons' giant 5-string upright bass was well served. Main losses occurred with synthesized bass and ultra-low drums.

Jäckle's woofer amp is a very clever design. It all starts with a complex multi-tasking input transformer. First, it provides galvanic decoupling by not presenting a ground reference to the speaker terminals. This avoids ground loops with the main amplifier. It also enables safe connection to a permanently bridged amp like Crayon Audio's CFA-1 whose terminals carry 12VDC regardless of polarity. Second, this transformer provides about 10dB of step-up gain. This is customized further via secondaries tapped from the already mentioned 3-position rear switch. Third, it acts as phase splitter for
the two halves of the floating-ground Circlotron amplifier. Fourth, the selected transformer secondaries couple directly to the gates of the output buffer Mosfets.

The bass amplifier thus becomes a single-stage impedance compensating circuit with passive transformer gain. It's a beautifully purist approach.

Upon delivery, minor assembly is required to bolt the small plinths to their upright frames. Now we encounter a number of peculiarities. First, this plinth has no provisions for spikes or bumpers; no leveling or stabilization features. Should your floor not be perfectly even or slope somewhat, you must reach for your audiophile tool box. To avoid floor wobble and lateral offset, I had to float the plinths atop three wooden discs each. Then one speaker needed shimming up to stand straight. Still, the combination of tall baffle, minimal footprint and lightweight plinth creates a propensity for rocking. The slightest finger push on the baffle incurs movement that takes five seconds to settle visibly, hence longer still to return to full mechanical inertia. Believers in the sanctity of stable wavelaunch platforms will cry foul. Or, they might invoke Jamo's massive cast-iron base and rear brace for how to properly rigidify open baffles. Others will counter that the perfect equality of opposing forces cancels out mechanically to not set off any movement. Of those, some might still prefer a more
confidence-inspiring solution à la Jamo. One could of course improvise and weigh down those plinths with external mass. But should one condone having to improve upon a €15,000 speaker to behave properly? No. Nor would cosmetics gain from any such self-help tweaks.

Not that the cosmetics aren't already compromised. As a reviewer, I'm a consumer by proxy. I find it inexplicable that today's speakers ship without rear covers. Driver motors, mounting bolts and hookup wiring as well as unfinished Plywood and painted cross braces are all in plain view. Granted, very few actual owners will place the Veena quite as far into a room as my current setup mandates. They could be spared a routine viewing of the speakers' entrails. Still, I find it impossible to argue that this design is cosmetically finished. Were I a buyer, I'd insist on a perforated metal grill to match the front. At the very least, a black cloth cover. It'd also keep pesky house pets and inquisitive fingers at bay.

Incidentally, those four series/parallel configured woofers are Spanish Beyma issue as fancied also by Tommy Hǿrning who augments his Lowthers with massively paralleled and isobarically paired woofers [left]. Claus Jäckle selected his Beyma woofers not for high voltage sensitivity. The passive transformer gain handles the matching to the Lowther. He selected this woofer model for its 0.45Q factor. It allows open-baffle use.

Claus Jäckle explained that very few commercial woofers are suited for such applications. They're designed instead for conventional sealed or ported boxes. His open-baffle dream started after hearing a pro woofer without a box. The quality of its bass haunted him forever after. What was to eventually become the Veena was literally built up from his obsession with dipole bass.

Photo compliments of Audio Exotics in Hong Kong

During the 1-year design process, Jäckle had of course compared various Lowthers for suitability. Their catalogue is quite deep after all. Interestingly, he didn't find the dearer variants to offer sufficient performance advantages to justify their far higher pricing. From his perspective, Lowther the brand then also offers other advantages like long-term availability and consistency. Jäckle investigated competing widebanders only to find them bedeviled by unacceptable variabilities or short-lived production cycles. Designing a speaker around a particular widebander only to see it discontinued a few years later could be a nightmare if one is not looking to release new models every two years. With Lowthers having been around unchanged for decades, they offer stability on a number of fronts.

As the above image shows, the Veena is curved in the front, flat in the back and angled on the sides. The actual driver mount baffle is recessed behind the front panel. That panel is a sandwich affair of multiple veneer layers. A central vertical slot for the drivers is covered behind a non-removable perf metal grill. Down at the base, the heat-sinked amplifier modules are not mirror-imaged. Hence both speakers sport the power IEC and backlit mains rocker on the left, the 3-position bass gain knob and single-wire terminals on the right.

What is theoretically appealing about open-baffle speakers? First, the bass cancellation between freely mixing front and rear waves creates null zones at the speaker's sides. Those nulls mostly eliminate the sidewalls as contributors to the usual room-mode issues in the bass. (Naturally, the floor-to-ceiling and front/back-wall polarities continue to operate). Two, the absence of a box eliminates box talk. That's short-hand for the various colorations whereby enclosure resonances dirty up the sound. Three, half the speaker's radiated acoustic energy isn't killed by absorption. Hence such a speaker doesn't suffer the same SPL loss over distance as conventional monopoles do. The Veena's specified 98dB in-room sensitivity already includes this 3dB rear boost. The bigger the listening space, the less obvious this ambient gain will be of course. I'm very familiar with where my preamp's master volume sits for my 91dB Tango R. The Veenas did not act like 98dB. That's because my room's lack of early front wall reflections diluted the audible impact of the rear-wave gain. An effective 95dB or somewhat lower rating even seemed rather more realistic for my scenario.

Claus Jäckle also explained how contrary to popular lore, the impulse response of open-baffle bass is superior to sealed boxes. A woofer properly designed for open-baffle use does not require the compressed-air spring action of a sealed box as restorative force. This, as earlier, admits that very few commercial woofers today actually lend themselves to OB schemes. Finally, a dipole speaker relies on a copasetic mix of reflective and absorptive room qualities. Too reflective a room can compound resonance issues. Placement experimentation is vital then and perhaps more than conventional speakers, dipoles should first be tested in their intended final location before committing to them indefinitely.

Once the above had published, we received Claus Jäckle's e-mails and the conclusion of the review was terminated.
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