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Reductionism. On the very first page of Sven Boenicke's—unpublished—speaker cookbook it specifies that he may only use drivers which require the absolute minimum in filter parts to play nice. He's not averse to using very costly tweaks from Bybee, Marigo, Stein & Co. or deep cryo. But he's adamant that only the most minimalist xover leaves the signal sufficiently unmolested to be acceptable. Hence 1st-order exclusively. If that means buying more exotic drivers and into a lengthy match-making process to identify the ideal mates whilst burying all others in the reject cemetery, that's the price to pay. Depending on allowable final budget it could even mean ultra-premium Duelund parts.

The same good book also conjectures on human bone being the most ideal enclosure material by duplicating what encases our ear/brain. In the real world solid wood becomes Sven's substitute of choice. Cherry is a favorite. Aluminium, glass and MDF are tromsig. Verkehrt. All wrong. As the photo showed, preferred bass loading is the undamped multi-folded rear line. The W5 brief wanted too compact a box to accommodate an effective labyrinth. Hence something closer to a bass reflex became the more practical means to extend bass response. A cabinet shop provides him with precision-machined clamshell halves, Sven does the rest. His penchant for different had me curious what goes on inside the W5 and what drivers survived his selection process. A look at his Studio 12 3-way (the front driver is a coax) drives home family genetics. Whilst the B models introducing his bent baffles had been conceptualized as lower-cost alternatives to the solid-wood models, actual production costs had eclipsed all estimates. The W5 was thus predestined to be carved from solid stock like the SLS [left] again.

On August 23 this story expanded. "Would you be interested to review Swiss-made Holborne components? Henceforth Meinrad Müller and I will be sharing my showroom in Basel for a permanent collaboration. It's a really nice match. If so, would you also be interested in visiting us and do a report or whatever you please?" I'd been in fact introduced to Holborne by their US importer during Munich HighEnd earlier this year. I'd committed to their purist tube-hybrid DC-coupled integrated but not heard back. So I accepted Sven's invite for a behind-the-scenes addition to this assignment.

I also learnt that over the last two months he'd taken his tyke into various systems and determined that he wanted a slightly different mix of direct and reflective sound. Less Peerless mid/woofer, more Fountek aluminium widebander. The new filter hinge had moved down to 600Hz like the very best Mark & Daniel two-ways with 5-octave AMTs and he was waiting for filter parts. Readers hip to how much overlap a 6dB/octave slope creates appreciate that the Fountek driver makes it well past 200Hz before its contribution becomes inaudible. So strike all notions of calling it a big tweeter. Sven reports that its on-axis linearity is superior even to that of the fantastic Tangband widebanders in his SLS and B models. The flat honeycomb membranes meanwhile counter with broader off-axis response. In the extreme nearfield milieu of the single-seat desktop that's not a factor of course.

The 14cm/5.5" Peerless SLS series mid/woofer loads into its 2.7 liter bass reflex enclosure with a minimum impedance of 6.3Ω at 200Hz. That driver's resonant frequency is a usefully low 47.4Hz whilst installation depth is 67mm to clear the W5's narrow profile.

As the cutaway renderings show, the FE85 Fountek loads into a sealed chamber with bullet-shaped rear wall whilst the Peerless encounters a short line of constant rectangular cross section. That line runs the depth of the enclosure but with a strategic down/up curvature to increase the operative length of this solid-wood port with smooth end flare.
Sven tried massive steel rods between the walls to experiment with mechanical damping but their added mass acted as an accumulator for kinetic energy to sound worse, hence the round recesses didn't become part of final production.

"The W5 gets MKP caps and air coils and metal-oxide resistors but of course no Duelund-style parts. Those also would not physically fit. I'm still considering offering the W5 with an external filter box with all my usual take-no-prisoners tuning stuff plus the very highest-quality crossover parts - just because this speaker design has truly crazy potential."

Crazy potential? Check your pulse. Nothing. Audiophile brainwashing conditions us. We correlate premium speaker things with big - lots of drivers, man-sized enclosures, floor-crushing weight. This box is tiny, its driver are just two and even on cone surface there's nothing to write home about. Surely our designer talked tall. Crazy potential indeed. For a flea symphony perhaps. But if we check our prejudices at the door, we might just admit that the point-source ideal favors small closely spaced drivers; and that if two such quality drivers emit sufficient SPL for our needs and cover ~55Hz to 20kHz, an active sub can easily flesh out the bass to make a complete presentation. The key qualifier is 'sufficient SPL'. Here hifi is full of bad intel about what those are and what type of power one needs to achieve them. This assignment would thus be perfect to blow some holes into related assumptions.