Phrases like high fidelity and perfectionist audio suggest a central norm to which all things audio should aspire. Not a bad idea, in some ways, but if you look at the wide variety of loudspeakers out there that people love, from the old-school Auditorium 23s to the high-tech KEFs and Vivids, it can be hard to figure out what they all have in common.
While I like the idea of objective standards, I also like that high-end audio has room for a variety of approaches—specific aural embodiments of excellence—each striking its own balance between personal (sometimes idiosyncratic) vision and eternal verities, including scientific verities. Getting the technology right matters, but there’s plenty of room for creativity.
Alta Audio’s Hestia Titanium loudspeaker ($32,000/pair), which I had in my home during late summer and early fall of 2017, is a fine example of a loudspeaker for which one designer used some interesting technology and a bit of innovation in the service of his personal vision of sound.
Hestia who?
Hestia is a goddess from Greek mythology, first-born sister to such better-known deities as Hades, Poseidon, Hera, and Zeus. Hestia’s father, the Titan Cronus, ate his children as they were born—all but Zeus, who later overthrew the Titans and forced Cronus to disgorge Zeus’s siblings. Hestia was the last cookie to be tossed, so she is, metaphorically, Cronus’s oldest and youngest child. She gave up her place in the Olympian Pantheon to Dionysus, god of wine, ritual madness, religious ecstasy, etc., so that she could tend the hearth. Hestia is, above all, grounded, rooted in the verities. She is central.
The loudspeaker named for her, the Hestia Titanium, designed by Alta CEO Michael Levy, is imposing but not huge: 53¾” tall and 135 lbs. The solid parts—baffle and bass cabinet—are wrought from a seemingly inert, multilayer epoxy material called DampHard. They come in one color, basic black, with a piano-like gloss.
The name Titanium comes from the metal, known for its light weight, strength, and stiffness—the metal itself was named for the Titans overthrown by Zeus. In audio, titanium is commonly used in tweeters, but the titanium in the Hestia is found in the drivers’ coil bobbins, aka formers—the cylinders the coils’ wire is coiled around to generate the magnetic fields that bounce the cones and make music. Formers need to be stiff and light, hence titanium. They also need to not get too hot. Morel, the company that makes the woofer and upper-midrange driver used in the Hestia, claims that eddy currents form less readily in titanium than in aluminum, another common bobbin material, because of titanium’s lower conductivity: more efficiency means less generation of heat. The physicist in me isn’t convinced, but in any case, Morel says that titanium formers make a driver sound “crisper.”
Those drivers are mounted in what Levy calls a Dipolito configuration—a play on words meant to convey that the Hestia’s driver arrangement has much in common with the well-known d’Appolito configuration, and that its open-baffle-mounted midrange drivers act as dipoles.
Levy told me that dipole speakers, including open-baffle designs, “have the advantage that their rear wave mimics a coherent soundwave moving in one direction, because it is in reverse phase to the front output and emanates from the same position. I have always liked the huge soundstage that you get because of that.” (footnote 1).
In a conventional d’Appolito design, symmetric midrange drivers offset each other’s destructive interference with the tweeter off axis, ensuring smoother vertical dispersion near the crossover frequency. The Hestia’s Dipolito topology riffs on that theme, placing one 6″ upper-midrange driver above the tweeter—a “specially modified version of [Serbian manufacturer] RAAL’s OEM ribbon,” Levy said—and two 7″ lower-midrange drivers sourced from Dayton Audio below it, the bottom pair matching the top one in frequency response and output, he told me. The advantage over the standard d’Appolito configuration, Levy said, is that the large combined surface area of two 7″ cones permits smoother, better matching to the 10″ woofer near the low-frequency crossover.
Levy believes—and my listening to the Hestia mostly supports this—that frequencies from the midrange down establish the acoustical context within which precise aural images are spun. “Since our brains always work toward maximum efficiency,” he told me, “they use the mid-frequencies to define the space, and the higher frequencies to detail what is in it. The lowest frequencies, which are both heard and felt, are used for sizing.” The Hestia’s asymmetrical crossover “brings in the tweeter at 24dB/octave while gently rolling off the midrange at 6dB/octave from approximately 2.25kHz, and was ear-tuned to meld the space-defining part of our hearing with the positioning, detail, and sizing part of our hearing.” The Hestia’s transmission-line woofer “uses a symmetrical 12dB/octave crossover at approximately 165Hz, and gives the bass information for us to hear and feel the size and weight of the source of the sound.”
Levy doesn’t stuff his cabinets with soft, fuzzy stuff, he says, because he thinks it makes speakers sound stuffed and fuzzy.
If it sounds as if Levy put a lot of thought and work into imaging and the accurate reproduction of the performance venue, well, that was my impression, too.
Setup
My listening room is big—its largest dimensions are 30′ by 24’—but irregularly shaped and multifunction; there are limitations on where big speakers can go, and each Titanium Hesta is bigger, with more and deeper bass, than any other speakers I’ve had in this room. I had to work harder than usual to position them and mitigate the inevitable room-related problems. And because the Hestias are awkwardly shaped, this was considerable physical labor.
Acclimating new speakers to a space, or vice versa, always means moving them around, but usually the moves I make are small. I moved the 135-lb Hestia Titaniums several times by several feet or more. I even moved them from one side of the room to the other, and back again. Eventually, I decided that they sounded best not far from their starting points. From there I made smaller moves, then even smaller moves—an inch this way, another degree of toe-in—until I thought the sound was at its best.
As usual with full-range speakers, the crucial factor was bass. If the Hestias weren’t properly positioned, their bass could overwhelm: too near a wall, and I experienced room gain at the lowest frequencies. Room modes—those pesky peaks and valleys—were readily excited. Because it’s big, this room has four resonant modes below 40Hz, the lowest at 17Hz. Modes so low are beyond the reach of most speakers, but the Hestias excited them easily. However, the biggest problem in this room is a cluster of modes between 60 and 70Hz.
No matter where I put the Hestias, they carved out an impressive sonic space, but certain positions enlarged the soundstage and clarified the images. When I got it right, a vague impression of the recording venue was replaced by a detailed architectural portrait in sound. With some recordings made in churches, I imagined I could hear where the columns were. Maybe I actually could.
Toe-in mattered. I began with the Hestias toed in by perhaps 20°—definitely angled, but with the speakers’ inner side panels still easily visible from the listening seat. I settled on just a hint of toe-in, the Hestias firing almost straight ahead. Ironically, the sound felt more intimate when the Hestias were looking past me; that configuration gave what sounded like a smoother frequency response, with a bit more midrange energy.
Something about the Hestias’ sound made me sit up straighter in my listening chair. When visitors listened to them, I noticed that they tended to stand, or sit farther back in the room. I came to feel that the midrange was slightly recessed when I sat significantly below the tweeter axis. Another small, apparent irony: Sitting precisely at the level of the two 7″ lower-midrange drivers seemed to suppress the midrange. I’m eager to see if John Atkinson’s measurements support this observation (footnote 2).
As it turned out, this problem of listening height was not so easy to solve. When I sit in my listening chair, my ears are just 34″ above the floor—a solid foot below the Hestia’s tweeter axis, the sweet spot for any d’Appolito array. I needed either to raise my ears or tilt the speakers forward. My ears are attached to my head, so I preferred the second option.
Some trigonometry told me I needed to tilt the Hestias forward by about 5.5°, but the provided spikes didn’t offer that much tilt. I moved a bar stool over, but it was too tall—and who wants to listen to music while sitting on a bar stool, except at a bar? I experimented with wooden Jenga blocks under each speaker’s rear edge. Fine, but . . . Jenga blocks with $32,000/pair speakers?
Footnote 1: But can this configuration possibly work? In the Hestia Titanium variant, the outputs of the two lower-midrange drivers will interfere with each other, with that of the top midrange driver, and with that of the tweeter. The resulting four-way interference will be complex indeed. Levy told me that the crossover between the midrange and the tweeter is asymmetric, the tweeter coming in much faster than the midrange fades out. That asymmetry adds complexity. To get it all to work together to minimize off-axis tweeter/midrange cancellation would require engineering so delicate that I’m not sure it’s even possible. I don’t doubt Levy obtains some benefit from his quasi-d’Appolito design, but I’m skeptical.
Footnote 2: I’ve mentioned my skepticism about the Hestia’s Dipolito/d’Appolito riff—but even an orthodox d’Appolito configuration can have off-axis cancellation well down in the midrange. For the deep technical stuff, check out this free version of an AES paper that addresses this issue: here.
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