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The Voxativ Ampeggio is a complete speaker. In this category and beyond the already stated reasons, that's not exactly common. Consider Feastrex for example. Their US importer's Granada speaker runs a digital crossover to augment the widebander with dual 15-inch woofers. Do you see much justification in an exorbitantly priced 'full-range' driver that requires augmentation to make proper bass? Next look at the enclosure Feastrex publishes for their 5-incher. It's a poor ported joke.


Now extend your search for wideband driver manufacturers who manufacture their own properly matched fully optimized non-DIY enclosures. You'll come up short. Jacob George of Rethm for one must deal with inherently limited drive units not of his own manufacture, then devise complex enclosures to minimize transducer compromises (and modify the actual drivers). After 10 long years, Jacob finally gave up on operating Lowthers full range. He now mates them to active bass systems instead. To purists, this defeats the whole concept. What makers of full-range drivers actually design their own advanced speaker cabinets as a cohesive whole with their drivers?

Lowther has a new range. There's Tommy Wu of JohnBlue Audio Art from Taiwan; Louis Chochos of Omega Loudspeakers - and Voxativ. This is rarer than it ought to be.


Single-driver speakers rely on their cabinets to linearize the response. There's no crossover to contour with. There's no electrical notch filter to trim presence region peakiness. Driver and enclosure must work as one without the assist of a filter network. To reiterate then, the Ampeggio's driver was designed and tuned especially for the Ampeggio cabinet - by the very same designer.


[At right, the field-coil version of the Ampeggio driver uses the same cone, voice coil, suspension and basket.]

"This is a properly engineered widebander. Do not stick it on an open baffle or in a ported box and expect optimal performance. To obtain Ampeggio's intended bass response depends absolutely on a carefully orchestrated enclosure. "


Asked about her driver's spectacular bandwidth, Inès explained that "increasing the magnetic field strength decreases the QTS Thiele Small parameters. The optimal QTS for a woofer (contingent also on its enclosure) is about 0.3. When QTS shrinks, bass becomes cleaner but amplitude reduces. If QTS increases because magnetic field strength diminishes, bass becomes huge but definition suffers. All this is standard MO for woofers. A fullrange driver works well with a QTS of 0.56 like the AC-3X.


"If the matching enclosure is properly designed, bass will be fine and lowering the QTS by driving up magnetic field strength in the voice coil gap will actually cause bass loss. Lowther's PM4 for example has a QTS of 0.227 and a resonant frequency of 70Hz (the AC-3X's is 33Hz). With that good bass is not possible but theoretically the highs are fine. The Lowther's frequency range is tilted at around 1000Hz. Other parameters influencing QTS are moving mass and suspension stiffness. Increase stiffness or moving mass and the QTS goes up. In the end, it's most important to fine-tune all of these parameters against each other to get the values you want. One starts with calculations but the rest is prototyping - endless prototyping."


The upshot is that the hunt for extreme sensitivity—without hornloading just as a function of the raw driver—eventually turns against bass extension. The AC-3X's core geometry and materials allow for a higher rating in fact than the actual 98dB specification of this speaker model. Inès strategically shaved off a few efficiency points by stiffening the suspension to optimize low bass. Excursion capability is ±8mm (Lowther's is ±1mm).


In this genre of drivers, Alnico—a contraction of aluminum, nickel and cobalt—enjoys a near mythical reputation. Because Voxativ uses an Alnico motor in one of their drivers but not the top offerings, I asked why. "I have repaired and rebuilt thousands of drive units over the last ten years. I always insert a special probe in their voice coils to measure remaining field strength in the gap. With Alnico it's invariably well below the original specification. Alnico only maintains magnetization wedged between steel plates. Fixing an Alnico core such that it cannot slip by impacts in transit or over time by even 0.1mm is critical. Otherwise field strength is seriously compromised. At the physical magnet sizes required for 2+ Gauss motors, this gets more challenging than one might think.


"In the AC-2a we have one Alnico driver because that's what some of our customers prefer. For our top drivers with max sensitivity however, the far higher and constant magnet strength of Neodymium allows for a motor size and weight reduction over Alnico without any sonic losses. With costly high-performance drivers, long-term performance invariability is key. This made Neodymium motors our choice."


Field coils too enjoy a mythical regard. "While I personally hear no advantages with Alnico, field coils are different. I simply cannot explain why. Our AC-X is my top driver and a field coil for a reason. Its sonic performance is superior to the AC-3X without altering any other parameters like the voice coil, diaphragm or suspension.


"You'll hear this for yourself once we release our pending top Wall Horn with a special version of the AC-X. About the Voxativ name, it combines the Latin vox for voice with another Latin term for future. It thus becomes Voice of the Future. The tag line for active listening which a clever advertising agency spun off is a nice secondary meaning derived from it."

Prototype Wall Horn with claimed 25Hz response
 

A distinctive Voxativ feature is directly related to price - the upscale audio furniture concept. The Ampeggio is a luxury piece of furniture dedicated to the audio arts. In a sector dominated by DIY, it sets Inès Adler's creation apart. Anyone commenting on this package cannot do so without acknowledging the build quality aspect. Or the extent to which the Schimmel collaboration has pushed the finish. Someone who considers a piano a fine furniture heirloom is bound to extend the same regard to Voxativ's Ampeggio. Those who couldn't give a shit—man cave dwellers to whom only sonics matter—would never consider allocating such a high percentage of a speaker's purchase price on finish no matter how perfect. For them the Ampeggio by design is off the reservation.


Actually, Schimmel Piano builds the entire Ampeggio speaker in their famous Braunschweig facilities. Voxativ simply dispatches hand-crafted drive units from Berlin. Order fulfillment happens through and from Braunschweig. Should we assume that a firmly established piano builder's wood craft—Schimmel is one of the few such firms remaining who offer a complete 9.5-year Master's degree—transcends the average plant pumping out doors, window frames and kitchen cabinets aside from the occasional time slots reserved for low-volume MDF speaker cabs?


Clearly the Voxativ is an expensive speaker. But there's a direct correlation with where the money went. You could argue that 13-skin lacquers and select tone woods applied by German perfectionists aren't how you wish to get invested. Fair enough. You simply cannot argue with the reality of the expense or the standard of implementation.


To summarize introductions: Voxativ is a 3-year old firm with longer roots and an accredited woman engineer in charge. The company isn't just about statement drive units. It's about statement speakers which happen to use a single driver - their own. While Voxativ drive units are available to DIYers, raw parts cost should mostly prohibit their actual use in such projects. Building ambitious drive units with little market representation—and then in not necessarily optimized implementations which would reflect poorly on the firm—is counter productive. Hoping for eventual OEM business hasn't gotten PHY's Bernard Salabert widespread exposure. His drive units to this day are used by only four very small loudspeaker companies. Seas' exotic driver range has very different resources behind it yet not even the Norwegians have launched their own line of Seas speakers to show off their widebanders as proof of concept.


Relative newcomer Voxativ now hits this scene in a very clever alliance with Schimmel Piano. Their joint project handles driver design, driver realization, in-house control and final implementation in an expertly crafted turnkey loudspeaker all in one fell swoop. That's daring and ambitious. It matters little of course if it ain't got that swing.

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