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Whilst Jefferson had sat in the sweet spot giving the final setup a critical ear, I'd sat off axis pretty much in front of the right speaker. There I noticed an occasional strange phenomenon. Certain tones would suddenly and very distinctly jump out of that ribbon tweeter. Think of how rippling water catches the occasional sun ray just so to cast off a brief glinty flash. Such micro bursts of dislocated energy would here and there arise like X marks the spot. This clearly identified the tweeter as sound source whereas I otherwise just heard coherent normal sound not assigned to specific drivers.
Peerless Vifa mid/woofer with Titanium voice coil,
coated natural wood-fibre 'pentacone' diaphragm
and butyl rubber surround
Once I'd explained it and Jefferson traded seats, he heard it too. Had it been a dome tweeter, I'd have blamed a grain of dust in the voice coil. But Jefferson was at a total loss to explain cause without his test gear. He didn't think it was mechanical in nature. And he'd never heard an Aurum Cantus do that before. We swapped amps to eliminate their cause and crossed channels. Yes, the right tweeter did act up a bit but only very occasionally and only when hit by just the right frequency. Jefferson would thus return a week later with a broken-in replacement. This would give me an unexpected opportunity to photograph it and the extracted tweeter horn plus sneak a glance at the speaker's innards.


On a vaguely related subject, upon delivery Jefferson had volunteered that the white paint finish of my loaner wasn't yet up to par. He disliked its coarse texture and wanted to transition to proper smooth lacquer instead. I'd simply requested white if it were at all possible. Since this was the very first pair where they'd tried out white to find it attractive and worthy of becoming a stock option, it's what he brought. And in our digs white really did look swell. When he picked up the pair at the conclusion of my assignment, he'd bring a proper white sample for me to inspect. Perfectly played.

I find live music's meatiness and tonal substance much diluted by hifi. To compensate a bit I'd either want a full-bandwidth omni like my HRS-120 German Physiks; or speakers deliberately tweaked for tone like Boenicke and soundkaos. But in our world of imperfections, specialization doesn't come free. It's very common to emphasize tone—Zu do this too—only to diminish the visual aspects of razor-sharp focus, discrete layering and so-called imaging holography. Which are hifi artifacts to begin with but there can be good reason for wanting them. During a concert our eyes fill in the gaps. We not only hear the bass guitar plucks, we see the player pop his strings. Without the latter for playback, many speakers exceed reality to add back certain quasi visual aspects. Usually this gives up meatiness in trade. That's the Horizon. It moves visual and transient exactitude up, tonal voluptuousness and substance down. That's no criticism, just a general flavour indicator. Though generalizations are false by definition, the Horizon acts closer to most ceramic-driver speakers than those fitted with paper membranes. One reason is its unusual transient fidelity. The other is its hornloaded ribbon which contributes a subliminally metallic edge.
the Job's very good-sounding Exicon power Mosfets
Even so—and this surprised me a bit—it worked really well on the Job225. Here it generated strong colour intensity which was a bit glossier than with the SIT monos. In hindsight this shouldn't have surprised. Jefferson is Goldmund's most important European retailer after all. He voiced his speakers with their 3MHz Telos amplifier circuits and the Job is a baby Goldmund. Preceded by my tubed Nagra preamp, I'd sign off on the combination without question. Considering how much more approachable this amp is over its Goldmund equivalent (that does get two power trafos and a flashier chassis), that's meaningful for a €12'500/pr speaker whose most direct competitor on overall concept as the Apertura Onira offers a more sophisticated enclosure yet only demands €8'775/pr. That predicts little about actual performance but does speak to value perception.*
There I'd expect that this standard rectangular MDF box with some unusual fascia detailing for grill retention and three good but non-exotic drivers plus bolt-on metal plinth might encounter issues. That's twice so given the brand's relative newness.


Add that retailer embrace to demo Grand Cru could be stymied by perceptions of unfair competition with the maker's deeper margins and knowing that Jefferson Hifi travel well outside their location to service customers.


That's of course exactly what a good retailer should do to add value to the transaction. In this case it could simply hinder Grand Cru Audio's ability to take on central Europe. But that gets us beyond discussions of sonic merit into areas each potential customer will decide for themselves.
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* I saw Jefferson's schematic. With 38 crossover junctions of which many use multiple parts to combine into the desired values (there are 23 junctions for the ribbon and 15 for the mid/woofers), a single not pair of filter networks takes one full day to assemble. None of its values are standard, hence the many combinant parts. All coils are sourced oversized and then wound back by hand. All parts are very stringently measured, matched and rejected if not to tolerance. The tweeter leg even includes a low-pass above 30kHz to eliminate the ultrasonic bands where phase begins to rotate. The tweeter high-pass and mid/woofer low-pass use compound or progressive slopes starting at 6dB/octave at the transition frequency then accelerating to 12dB and finally 24dB roll-offs. By comparison Jefferson believes that the Onira crossover consists of just 8 parts. He explained that this major offset in raw parts accounts for their difference in price. But since the crossover is internal and potted, it's invisible. As such it's not something that registers on value apparent to the eye. It reminds us to never judge a book by its cover.

Keeping our focus on performance, the Horizon proves that for utmost amplitude and impedance linearity a complex filter network is very much required. Whether a textbook 1st-order filter's most minimal parts count makes up for its far lower precision without further response corrections by adding more 'immediacy' is another discussion. One could certainly compare different designs by ear. Determining precise cause for one's observations is simply a different matter. If it did indeed sound better on certain aspects, would our imaginary 1st-order speaker be better because of its simpler filter; different cabinet and drivers; the interaction between it and our particular amp; its internal hookup wiring; how it played our room; and to what extent for each? All I'll say on this subject is that relative to amplifier friendliness or apparent ease of load behaviour, there's no doubt in my mind. Jefferson's complex filter posed no audible issues for my micro-power transistor amps by way of comparing their performance to that of a DC-coupled low-output impedance amp of more than 10 times their power. I'm familiar with the 'more parts = higher reactivity' argument. In this case I simply wouldn't know how to pin it on anything. To be argumentative, I might instead propose that the big electrolytic power supply capacitors, coupling caps and miles of transformer wires in valve amps are sonically far more detrimental than whatever exactly is in the Horizon. But those are academic disputes best left to the forums.