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As the French Goldmund importer/distributor whose amps like Spectral champion very wide bandwidth, extended response could be vitally important to Torno to minimize HF phase shift, hence his fondness of ribbons. This sketch shows how internal triangulation breaks up some of the parallel walls all usual rectangular box speakers exhibit. These angled window-pane braces create some inside loading and also stiffen the enclosure side panels. The solid middle brace then subdivides the interior to give each mid/woofer its own dedicated chamber to play in.


The 38-parts potted filter network divides into high/low-pass sections behind the tweeter and near the terminals respectively. It was designed to "work best at 30-40cm front-wall proximity as a reasonable domestic distance." The port flares combat turbulence and chuffing to decompress their 18cm drivers with 3.2cm voice coils. The asymmetrical baffle geometry mandates mirror-imaged production to complicate manufacture over identical units.


On the sticker for a compact 3-driver box from a French hifi retailer, a Gallic forum poster opined that the price was rather high given that the brand itself had little global traction. He felt that made it a riskier buy than giving his money to one of the well-established broadly distributed speaker houses where resell value—given typical audiophile buy/sell cycles—was far more of a sure thing. As usual, I'll take the fifth and focus solely on performance and whether that seems commensurate with competition I'm familiar with. On that front but still from a tech perspective, very flat frequency response as is promised here does tend to require complex filters. Jim Thiel was another designer who stood the 'keep it simple' 1st-order filter mantra on its head by using many more than just textbook parts to achieve high linearity.


That more parts would combine into an easier amplifier load than fewer bits must directly relate to impedance and phase stabilization. Again, that's a very interesting subject which proposes—rightly if you ask me—that an intrinsic part of a speaker's performance and thus sound is how little or much it stresses out the amplifier driving it. It's a more holistic view on how hifi systems actually work.


To learn more about the Grand Cru brand and the Horizon project in particular meant chatting with Jefferson Torno via his store partner and translator Nicolas Gillett. As it turned out, they had a mere 45min. drive to Basel before traversing the north/south axis of Switzerland to hit our digs in the Lavaux region of Lac Leman. Crossing customs with shiny speakers in their car trunk simply took a good hour of waiting in a lane behind massive lorries.


Googling would chance upon this Iris speaker model which can be seen referenced as both Tanagra and Grand Cru to reiterate that one brand morphed into the other. The hornloaded ribbon tweeter certainly previewed what became the Horizon. The upper photo of a Paris hifi show exhibit shows mighty Telos 350 Goldmund mono amplifiers driving these two-ways. The Absolue Créations cabling would seem nearly obligatory given the speakers' internal hookup wiring.

The beginnings of Grand Cru Audio date back to Jefferson working with Christian Yvon of French Apertura speaker brand. Today Yvon still helms Apertura*. As his former distributor, Jefferson split off as Tanagra Audio which eventually led to Grand Cru (a former Apertura model was actually called Tanagra to explain why a brand of that name would be short-lived to avoid confusion). The Iris was a quasi precursor of the Horizon. More specifically it'll be a direct pater familias to a forthcoming smaller Grand Cru that'll 'behead' the upper Peerless mid/woofer of the Horizon to turn into a floorstanding Essentiel. Grand Cru speakers are fully built in Italy by Joseph Szall's FinAudio facilities.

Szall of course is not only the designer of the Capriccio Continuo brand but also the brains behind ATD drivers whose unique mid/woofer with his 'elliptical crossover'** showed up in the original Magico Mini and remains in use with Volent Audio; as well as consultant to brands like Sonus faber. Jefferson mentioned how the Italians had never seen a crossover as complex as his but did a superb job assembling it to very tight tolerances.
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* Today's Apertura Onira and Enigma flagship suggest ongoing parallels between these brands as a shared preference for narrow enclosures, ribbon tweeters, two-way circuits and complex networks. Christian Yvon describes his progressive types as dual resonant intermodulation minimization or multi-elliptic Cauer filters which use independently adjustable ripple behaviour in the pass and stop bands. A triple transition slope begins at 6dB, progresses to 12dB then 24dB/octave for a stabilized rejection ratio of nearly -40dB. Prior to Apertura Yvon co-designed with Georges Bernard the Goldmund Dialogue, Apologue and Epilogue speakers.
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** Joseph Szall's descriptions of his own 'Transfert 0' filters with an "elliptical multi-slope transfer function" create yet further connections.

As a self-professed pure autodidact, Jefferson claims to not only have read all the usual technical books on speaker design. He dove just as deeply into various research papers on exactly how—scientists believe—human hearing works. This led to his conviction that linear phase and proper time domain behaviour are far more important than the mainstream acknowledges. Working in hifi retail for three decades and delivering/setting up systems all over France into Switzerland and Benelux also gave him a first-hand perspective of interfacing directly with the end user. That differs from the majority of designers whose actual clients are the dealers and distributors who pay their bills. Their interaction with end users is far more indirect. Amongst other benefits Jefferson called this intimate customer connection responsible for burning out his original focus on just pleasing himself. He now designs what his customers want and need and feels that this shift has made him a better designer. Another benefit was/is hearing many competing products in all manner of installations to observe specific shortcomings. He'd love to carry more brands in his store but has a really hard time finding any he can get sonically behind.

Grand Cru measurements are always taken at both 1m and 3m to verify actual behaviour at standard listening distances. The Horizon's port tuning is claimed to behave halfway between conventional ports and sealed loading. Jefferson's preference for ports was being able to use bigger magnets on his mid/woofers. That's due to the ports' decompression of the trapped inner air. And bigger motors translate directly to higher control. His preference for front-firing ports was to get their output in phase with the drivers, not for the usual reasons. The tweeter horn's asymmetry is a direct - er, reflection on minimizing sidewall reflections. Hence he set up his speakers with their narrower horn flares facing out (i.e. opposite to the earlier show photo). The depth of the solid-wood horn also locks in physical time alignment by setting the ribbon's acoustic center in the same vertical axis as the mid/woofers without requiring an indented baffle.

The R&D phase of the Horizon project spanned nearly two years and four prototypes. One of the last gremlins to be ironed out was a small measured response wrinkle ~200Hz. The precise placement of the two ports—the upper one closer to its driver, the lower one farther away at a very specific height from the floor—plus obviously their lengths and diameter are the result of much software modeling, then measurement and listening confirmation. Though Jefferson admits that they're physically less robust than their competitors, Eichmann terminals were de rigueur for their superior performance. At the time of his late April visit, the first 20 Horizon pairs had sold. An order for the next 50 had already been placed with Italy. Grand Cru were readying themselves to take business beyond the French borders. Hence also the solicitation for this review. The brand was desirous to go global.