Evaluating a loudspeaker that would become Stereophile‘s 2011 Product of the Year, Art Dudley, at the time the magazine’s editor-at-large, wrote, “The Voxativ Ampeggio went beyond sounding good: More than once, with too many records to mention, I found myself stopping to marvel at its brilliantly good pitch certainty. In terms of being able to simply nail a note, whether in isolation or tucked within a whole string of the little bastards, I’ve heard few other speakers this accomplished. And while it’s one thing to focus on such a characteristic for a moment at a time, it’s quite another to bask in it subconsciously—and the Voxativs allowed me to do just that.”

“I’ve now encountered a single-driver dynamic speaker I could live with,” Art concluded. “In most audio reviews that’s faint praise, but in this one it’s a revelation.”

I quote Art’s review not only as an homage to the man (who has now been gone four years) and the unrivaled clarity, flow, and humor of his writing but as an introduction to a loudspeaker he would surely be reviewing if he were still with us.

Launched in 2008 by Voxativ’s Inès Adler, the Voxativ Ampeggio has now been resurrected as the Ampeggio 2024, with an optimized cabinet, a redesigned support system, and a choice of 8″ full-range drivers (the original driver was 7″). In 2011, at the time of Art’s review, a pair of Ampeggios cost $29,750. Today, the base-model Ampeggio 2024 with the paper-cone AC-1.9 driver costs $13,900/pair.

The Ampeggio 2024

Adler’s resumé is impressive. An engineer veteran of Mercedes-Benz, she holds 23 patents. Her studies in mechanical and electrical engineering and thermodynamics prepared her for her role with the team that developed the first fully electrical diesel injection system.

I first encountered the Ampeggio 2024 in 2023, at that year’s Capital Audiofest (below), powered by Voxativ’s 12Wpc, single-ended T211 integrated amplifier. I reported that the Ampeggio 2024s streaming Jacques Loussier playing his unique, jazzified Bach “breathed, tossing out music well beyond physical boundaries. The presentation had punch, precision, and presence in spades. … The Voxativs played big and generous of soul and disappeared, regardless of genre.”

Ampeggio 2024s holding court at the 2023 Capital Audiofest.

Every Voxativ loudspeaker is assembled by hand in Voxativ’s Berlin factory, by Adler and her three-person team. In addition to 14 single-driver speaker models, the company makes and sells 16 full-range drivers for DIY projects (footnote 1). Why full-range?

“A full-range driver provides the perfect point source, and without a crossover,” Adler said. “Capacitors and coils”—inductors—”work like little batteries; they keep part of the music, better to leave them out. With my experience of now 40 years in speaker and driver construction, I’m still learning and optimizing.”

Voxativ’s full-range driver is available with many variations. For the Ampeggio 2024, Voxativ offers a choice of two drivers, the AC-1.9, which, when chosen, results in a total speaker price of $13,900/pair, and the AC-4B, which raises the price of the Ampeggio 2024 almost to the level of the original Ampeggio: $26,900/pair. The AC-1.9 is made of a smooth, heavy paper known as Simili Japon. The AC-4B is available in wood or the same paper, but wood is recommended; on both drivers, the whizzer, which extends the highs, is made from Simili Japon paper. The cone is set in a diecast-aluminum frame with a surround constructed of a “special foam” made in Germany that’s said to last 10 years. “It’s absolutely resistant to humidity and the things that make surround foams break in other designs,” Adler said. “We’ve used it for 15 years with no problems.”

Like its 2011 predecessor, the Ampeggio 2024 is a back-loaded horn speaker, which means that its full-range driver fires forward into open space while the cabinet it fires from serves as an extended horn for the backwave.

What are the challenges in creating such a loudspeaker? “You need a lot of experience to implement a full-range driver in a housing,” Adler responded over email. “Because Qts and behavior between driver and housing must match. This is the biggest challenge in the construction.”

For those of you who aren’t speaker builders, Qts, or “total Q,” is the “quality factor” of a loudspeaker driver, a measure of how well damped it is or how poorly, factoring in both electrical and mechanical damping. Higher Qts equals less damping.

Qts is a primary determinant of the suitability of a driver for use in a particular loudspeaker design. A rule of thumb says that a driver with a Qts between 0.4 and 0.7 is most suitable for a sealed-box design, for example, but it depends on the specific enclosure, and exceptions are common.

What makes the two available drivers different from each other? Damping factors, sensitivity, and magnet material. The cheaper AC-1.9 driver has a ferrite magnet, a Qts of 0.66, and a sensitivity of 91dB at 60Hz and 97dB at 5kHz. The more expensive AC-4B driver uses a neodymium magnet and has a Qts of 0.40—lower Q means better damping—and is significantly more sensitive: 96dB at 60Hz and 100dB at 5kHz. In addition to aiding resolution, Adler says, the wooden cone on the AC-4B “smooths the mids and highs,” but at the expense of some low end.

“The best overall choice is the AC-1.9,” Adler suggested. “It can do female voices as well as metal music. The 4B series is the better choice for resolution enthusiasts. It’s the most well-tuned version. Higher-level drivers have more resolution in the highs, but the bass reproduction is lower. A Voxativ Bass Module is recommended when using the Ampeggio with the 4B driver.”

Both Ampeggio drivers have a phase plug made of aluminum or brass or, for an additional $295, oiled and polished birch, maple, or oak. Regardless of the material choice, the phase plug “guides the high frequency waves out of the driver center,” Adler wrote.

“The phase plugs help guide the coloration of the higher frequencies,” Adler added. Output from the AC-1.9 driver is “a little lower in the high frequencies. You can push it by using an aluminum or brass plug; the brass is a little prettier. Both are cut on CNC machines. If you have an amplifier where the coloration is more peaky, then you use a wooden plug. Customers can order what they like.” In terms of sonics, “metal is a bit more clear and cold,” Adler said. “Wood sounds smoother.” My review pair came with paper-cone AC-1.9s and wooden phase plugs.

As a single-driver speaker, the Ampeggio is, of course, crossover-free. It is connected to custom-made, pure copper binding posts via a short run of a Voxativ-made wire consisting of “eight strings of solid-core pure copper and a small string of silver, and the shield,” Adler told me over Skype.

The new 8″ drivers required a new, matching horn. The walls of the Ampeggio’s twice-folded horn cabinets are built by a small Polish piano company of 22mm MDF; the cabinets of the original Ampeggio were built in the German Schimmel piano factory, out of tonewood from Schimmel’s collection. The new 2m-long horn is 8% longer than the original, the mouth 12% bigger with optimized folding and a back chamber that’s a little bit larger. That big mouth vents toward the listener at the bottom of the cabinet.

Footnote 1: The DIY drivers become increasingly exotic as you go up the scale, ranging in price from $1999/pair to $69,000/pair for the AC-XHB, which have both field coils and neodymium magnets.

NEXT: Page 2 »

COMPANY INFO

Voxativ GmbH
Schmiedestrasse 2
15745 Wildau bei Berlin
Germany
contact@voxativ.com
+49 179 2924224
voxativ.berlin

ARTICLE CONTENTS

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The Full-Range Driver
Specifications
Associated Equipment
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