Estelon XB Diamond Mk.2 loudspeaker

I remember, at High End Munich 2019, setting eyes on one of the most attractive loudspeakers I'd ever seen, in the color that, as I now know, Estelon calls Ocean Mystery. I remember it as a passive demo, no music playing, seen through glass; whether that memory is strictly accurate I don't know. Memories are funny things.

That speaker was about as tall as an average-sized woman and weighed twice as much (not that I lifted it, or attempted to). Its cabinet seemed to carve out the least possible space while encompassing all its parts—nothing spare, nothing wasted. With black drivers contrasting that blue metallic paint, and those sensuous curves, it reminded me of nothing so much as an elegant sports car. I wanted to climb inside and take it for a spin on the nearby autobahn—or, better, the Pacific Coast Highway. That speaker was the Estelon Forza.

Michael Fremer reviewed the Forza a couple of years later; in fact it was exactly a year ago, in the November 2021 issue. He described the Forza's low bass as "prodigious" and "well-controlled." Its soundstage, he wrote, wasn't the largest he'd ever heard (footnote 1), but it was "ultrastable," populated by precise images. He concluded: "The Estelon Forza is a costly, well-engineered, striking-looking, exciting-sounding loudspeaker that, with the right associated equipment, is capable of delivering spectacular sonic performances."

I finally heard the Forza earlier this year, at AXPONA 2022, driven by Krell's KSA i400 amplifier. In a big room, with EDM music (Cristoph?), I felt the Forza's bass pressing against my chest, a musical massage. Yet, the Forza was delicate with delicate music. Frank Sinatra sounded lovely and pure, if also much larger than life. I was only in that room for a few minutes, but I was as impressed by what I heard as by what I saw.

So, when Aldo Filippelli, Estelon's VP of sales and business development for the Americas, proposed I review an Estelon loudspeaker a bit further down the line—the Forza is second from the top of Estelon's lineup, behind only the Extreme—I accepted the offer eagerly.


The Estelon XB Diamond Mk II
The Estelon XB Diamond Mk II ($58,000/pair in standard finishes, $65,200/pair in Red Rocket, as equipped) is the second speaker in the Classic series, after the X Diamond. The XB and the XC come in standard, non-Diamond versions, but the X is available only in Diamond. The difference between the standard and Diamond versions? You could probably guess: The Diamond models have a diamond tweeter.

Estelon's marketing emphasizes synergy, but a set of specific technologies distinguishes the speakers from the crowd. Most obvious is its heavy, shapely, composite-marble enclosure, presumably bits of marble in an epoxy matrix. Such materials are usually inert, with excellent internal damping due to their complex microstructure: In such materials, vibrations can't travel far without encountering some vibration-damping microbarrier. What's more, it's a material that can be molded to virtually any shape, inside and out. Curved surfaces and irregularly shaped spaces can reduce diffraction and spread the frequency of airspace resonances (respectively).

Hard materials, though, due to their very hardness, couple poorly to the air inside, avoiding cabinet resonances but leaving the resonances that exist in the air inside—and there are always airspace resonances—to vibrate with full force. That is why the airspaces in the XB Diamond are lined with "different natural and synthetic dampening materials," which are "strategically and scientifically placed" to "create the best [damping] effects at different frequencies." (This and most other quotes in this review are from a technical document shared with me by Estelon.)

There's a certain design perfection, a lovely symmetry, about three-way speakers like the XB Diamond, with a tweeter, a midrange, a woofer—one driver for each frequency range—plus a port. (In contrast to the sealed-box Forza—although I hesitate to use the word "box" to describe the Forza—the XB is a bass-reflex design.) Design each driver well and match them optimally, with well-designed, well-suited crossover filters in between, and it's possible to make a loudspeaker of simplicity and elegance. Whether Estelon has achieved that remains to be seen, but the ingredients are there.

Estelon uses Accuton drivers, designed by Accuton engineers to Estelon's specifications: an 8.7" woofer with a ceramic-sandwich diaphragm, a 6.25" ceramic-diaphragm midrange—technically a midwoofer—and the previously mentioned diamond tweeter, which has an inverted (concave) dome onto which diamond dust—Estelon says nearly a carat of the stuff—has been vapor-deposited on an ultrathin, inverted aluminum diaphragm. Estelon claims that, as a result of the dome's high ratio of stiffness to weight, the first breakup is "close to 100kHz" (footnote 2), which should keep any audible consequences of that breakup well above the audible range. The tweeter is mounted inside its own subchamber, absorbing the back wave and isolating it from any midrange interference. Estelon goes on to note that "A similar version of the Accuton diamond tweeter can also be found in the dashboard of the supercar Bugatti Chiron," a claim I may need to verify first-hand (footnote 3).


Crossover points are specified as 80Hz and 2.1kHz. The woofer/midrange crossover is interesting: The woofer utilizes a second-order filter on its top end, said to "complement the natural acoustic roll-off of the mid-woofer performing in an optimized closed box." If I'm reading that right, it means that the midwoofer has no electrical filter on its bottom end. (And of course, only the woofer—not the midwoofer—is reflex-loaded, hence the "optimized closed box.")

All other crossover components are second-order, too, according to that technical document—a change from the first version of the XB Diamond, which mixed second- and third-order crossovers. Second-order crossovers complicate loudspeaker design and require exceptional transducers. So why go to the trouble? "The upside and the results are more dynamic bass, more detailed and resolving of fine micro-dynamics, and allows acoustic instruments to have a more lifelike reproduction. The speaker is much more coherent, sounds faster, and more natural at the same time."

That, though, may be an oversimplification: "We design the least complex filters while still striving for correct timing, phase, and magnitude response, with minimal parts to retain the life-like nature of the music," that technical document said. "The components selection, the placement, the vibration damping, and the wiring and connection techniques will achieve the desired result. Therefore, the filter orders are more of a guideline for our goal which is the best possible sound."

Crossover components are top-notch: Mundorf SilverGold-Oil capacitors and Carbon-Silver and Supreme resistors—"all of which are measured and spec'ed to extremely tight tolerances before using in the crossover production." Internal wire is by Kubala Sosna. Connectors are by Furutech. The crossover is located in a chamber of its own, isolating it from vibrations many other crossovers are subject to.

The positioning of the drive units is unusual in that the woofer is positioned quite near the floor and the midrange driver is above the tweeter. The former feature facilitates coupling to vertical room modes (which are uniform throughout a room) and energizing the room efficiently. The curved front of the cabinet aids dispersion and aims the drivers directly at the listening position. Indeed, Estelon seems to be claiming a time-coincident design: "This means that the sound from each driver reaches the listening position at the same time, resulting in a fast and precise sound signal with incredible dynamics, tonal balance, and realistic imaging and staging." I'll be interested to see what JA's measurements show.


No gimmicks here; all these details are directly related to performance. It adds up to a sophisticated loudspeaker with details carefully considered, conceived and apparently built to high standards. It's pretty, too. A lot of money for a lot of speaker.

Speaker in the house
Each Estelon XB Diamond Mk II loudspeaker arrived in its own, very nice flight case, with wheels on one edge and several handles (spring-loaded metal plus fabric-strap loops), making them exceedingly easy to maneuver. The speakers themselves are thoughtfully packed inside those cases, also on wheels—substantial ones—which made it easy for one person to unpack, despite their substantial weight (150lb each), although an extra set of hands is recommended. If you follow the instructions, you'll end up rolling each speaker slowly down a short ramp, out of the flight case and onto your listening room floor. I managed it just fine, but get a helper if you can. Opening the upright crate containing almost $30,000 worth of speaker and making sure it descends the ramp in a controlled manner—doesn't come crashing down—is unnerving the first time you do it.

Another advantage when it comes to unpacking, setup, and repacking: All the drivers are covered by rigid cages, so there are no exposed cones or domes.

After I rolled the speakers down their ramps, I rolled them to the spots the Wilson Alexx Vs previously occupied. I kept them close to that spot for a couple of weeks, moving them forward and back and side to side in smallish steps, tweaking toe-in. I wasn't happy.

Then the XB Diamonds started talking to me. Speakers do that sometimes; it's mysterious. They don't speak in actual words, but as I listen, they tell me where to move them. It's a tangible sonic/aural force, felt by the body rather than heard. It's strong.

As soon as I started paying attention, the XB Diamonds said, "move us farther apart." I did, and the pressure lessened (footnote 4). I kept going. When I was done, the speakers were about 10' apart tweeter to tweeter—a little more—roughly a foot farther apart than the Wilsons (which were set up in my space by Wilson's Peter McGrath and Chris Forman of Innovative Audio) had been, and a little bit farther out into the room. I moved my listening chair back a little, to about 10'6" from each speaker.

Everything was better now. All of us—me and the two speakers—breathed easier.

Estelon recommends a slight toe-in—not quite straight ahead but also not straight at the listener's ears. I played around with toe-in until it seemed right; more than slight but well short of aiming at my ears. This was all very easy, because the speakers were still on wheels.

Footnote 1: He also said it might be larger in a larger room, and I think he might have been right.

Footnote 2: A similar tweeter on the Accuton website has a breakup mode just above 70kHz.

Footnote 3: Because that would involve driving a Bugatti Chiron.

Footnote 4: Some readers will be skeptical of the notion that the speakers tell me where to move them; others will know exactly what I mean.

Alfred & Partners
US sales agent: Aldo Filippell
(630) 484-7577

MatthewT's picture

Wish we had some locally to hear.

georgehifi's picture

Then the severe roll-off of both Wilson and these in the upper treble after 10khz, like the tweeters have been zobel'ed as they did back in the bell rigger old days of tweeters

Cheers George

John Atkinson's picture
georgehifi wrote:
Then the severe roll-off of both Wilson and these in the upper treble after 10khz, like the tweeters have been zobel'ed as they did back in the bell rigger old days of tweeters

From the in-room measurements text: "The responses of [the Estelon and Wilson] speakers gently slope down above 5kHz due to their tweeters becoming more directional as the frequency increases and to the increased absorption by the room furnishings in the treble. (What you don't want to see with a spatially averaged in-room response is a flat treble output, which will sound excessively bright/shrill.)

John Atkinson
Technical Editor, Stereophile

Anton's picture

I wonder if they have to send royalties to the KEF Muon?

They look like 60% of a Muon.

If these were in my budget, I'd lust after them, for sure.

georgehifi's picture

Yet JA the $28k KEF Blade Two Meta you measured a couple of months back are almost flat out to 20khz. No mention of them being excessively bright/shill.

Cheers George

Kal Rubinson's picture

That graph for the Blade 2 Meta is a near-field "anechoic" measurement while that for the Estelon and Wilson is "a spatially averaged in-room response." The Blade will also show some of the same roll-off if measured under those conditions.

georgehifi's picture

"That graph for the Blade 2 Meta is a near-field "anechoic" measurement while that for the Estelon and Wilson is "a spatially"

We should have consistency in the way they are measured then, when these speakers are both measured just 2 months apart from each other but in different ways, all it serves to do is confuse matters to think there's something to hide or to confuse?

Cheers George

mieswall's picture

I think measurements are consistent. In-room, spatially averaged measurements are done when loudspeakers are so big or heavy they can’t be measured in JA’s lab. Regarding the blades, you should compare them with the semi-anechoic measurements of these ones.

Anyway, it would be nice to have a detailed description about where in the room those averaged measurements were taken, distance to loudspeakers, room size, reflections and treatment, etc.

Kal Rubinson's picture

There is consistency as the near-field "anechoic" measurement is always included and that appears as Fig.3 here for the Estelon.

Glotz's picture

The measurements parameters stated are oft-repeated throughout the decades of this publication.

MBMax's picture

they sound amazing. But just. So. Very. Ugly...

georgehifi's picture

Got that right, But I'll add butt before ugly.
They look like salt and pepper shakers maybe??

Cheers George

Anton's picture

I still like it, though!

David Harper's picture

on the shortcomings of overpriced speakers. well done.

JHL's picture

...familiar with your drive-bys question if junior scientists could even begin to define over-priced in coherent terms. Of course, the same is probably true of coherent sound and probably even passable speakers, but we get the picture.

It's interesting - if numbingly boring - watching the junior scientist gang expel so much subjective, arbitrary, ignorant, and belief-based prose while at the same time exhibiting scant capacity for identifying better sound. You'd think that as a test of savviness and validity there'd be a linear relationship between walk and talk.

But there isn't. This being a bona fide high end publication, that latter at least should alert them. It won't either, but in a rational, civil world, it would. Listening with graph paper it is.

ChrisS's picture

Better now?

MhtLion's picture

Thanks for the effort and great writing technique. However, I personally do not find much value in this review. What's the point of any review without a proper comparison? Say you don't have a good basis to compare it to other speakers in the similar price range, then why don't you pass it to someone in your editorial team who has the right background? Sure, there are some value to be found on entirely subjective review. But, isn't that just as good as any review on Amazon. What makes this review 'professional'? You had or still have Alexe V. I understand Alexe is much more expensive, but only comparison you had is just casually mentioning a hotter mid-treble and that's it. The only other comparison you have is one sentence about quirky space things about Alta Audio and Audio Vector. My take on this review is either Estelon XB Diamond does not worth much if compared to other top players in the price range. Or, it was so good it put Alexe V to the shame.

JHL's picture buyer's guide not free enough for you? And if you were sorry for the offensive comment, why did you deposit it anyway?

MhtLion's picture

I paid Stereophile magazine subscription for over 6 years. Does that give me a little more right to complain? When you like something enough, I think people are bound to make a criticism time to time. Like your favorite sports team. Do you pay for anything therefore you complain?

JHL's picture

...will run comparison panel tests of all dozen and a half types of $50,000-$75,000 audio products for you.

And $10,000-$25,000 and $25,000-$50.000 and $75,000-$100,000, and...

ChrisS's picture

If you can afford the Alexe V or this Estelon, you don't need reviews.

Go listen for yourself.

georgehifi's picture
AnalogueFan's picture

What great news!

hiendmmoe's picture

Though they sound incredible and are visually stunning their cabinet material is prone to chipping.
I was helping a local dealer fit his with their spikes and when we tilted the speaker to the side the edge of one slightly nicked the floor causing a nice size chunk to chip off. I was alarmed more than he was that a $85,000. Speaker could be damaged so easily.