Acora Acoustics SRB Loudspeaker

As a breed, high-end speaker designers tend to be passionate about their own particular design predilections. Andrew Jones wouldn’t dream of building a speaker that lacked coincident drivers. Daryl Wilson is adamant about the importance of inter-driver timing. Magico’s Alon Wolf will build a ported enclosure when hell freezes over.

Valerio Cora, founder and designer of Acora Acoustics, the relative newcomer who has already made major waves in the industry, is equally passionate. In his case, the object of his fervor is stone. Indeed, Cora’s obsession with the use of stone for speaker cabinets goes beyond mere philosophy. For him, the preference for stone is personal.

Cora spent three months in Italy every year until he was 18 years old as part of a family whose business was stonework and machining. His father served as his mentor, teaching him the intricacies of various stones: their characteristics, how to work with them, how to select the best. Cora knows the material intimately because, in a very real sense, stone is in his blood. 

But Cora is a scientist by training, so if you ask him why he chose stone—specifically granite—for his flagship SR speaker series enclosures, he won’t regale you with tales of his youth. Instead, he’ll dispassionately explain why “it’s simply the best material to make a speaker out of.” Why? “It’s stable. It’s inert. It’s rigid. It doesn’t bend, deflect, or compress. It holds the drivers precisely in place, with no movement, and it doesn’t allow the rear wave to interact with the front wave. Granite doesn’t allow sound waves to penetrate through it or contribute any sound waves of its own.”

Ask him his feelings toward other common speaker materials and you’ll get a terse response. Wood? “Not sufficiently stiff or dense. Too compressive. Not airtight.” Aluminum? “Better, but still more elastic and less dense than granite.” One knock Cora has against virtually all non-stone enclosures is that they require bracing to achieve adequate stiffness. In his book, bracing is bad because “sound waves from the back of the drivers reflect off the bracing and come back to the front of the drivers.” Consequently, Acora speakers eschew bracing altogether. Besides being sonically deleterious, bracing is superfluous in a speaker made of granite.   

Nor is Cora any more complaisant when it comes to other aspects of speaker design. For instance, all Acora speakers are 2-way. The reason? “It’s nearly impossible to achieve phase coherence with a 3-way passive crossover. You always have to make more compromises than with a 2-way.” Nor are Acora speakers

time-aligned in the vein of a Wilson, Vandersteen, or Rockport. Like Magico’s Wolf, Cora feels that “time-aligning drivers creates compromises that outweigh the benefits. Also, it’s physically impossible to be time aligned at all frequencies. But we employ a sloped baffle to achieve a phase-coherent alignment between the drivers.” How about first-order crossovers, then? “No. Too much driver overlap between drivers—up to six octaves at the crossover frequencies.” And as for sealed enclosures, “I prefer the bass extension of ported designs.”

Cora is equally picky about his drivers. For example, he doesn’t use diamond-coated tweeters, saying, “Maybe in the future. Right now, they don’t meet my sonic target. Remember, if you’re coating something, you’re adding weight to it.”

Nowhere will you find more evidence of Cora’s uncompromising exactitude than on the matter of granite color. The SR Series speakers are, like a Model T Ford, available in any color you’d like so long as it’s black. That seems draconian, but, as always, Cora has reasons grounded in knowledge. “Different colors of granite have different densities, all lower than black. Veins of color are actually cracks that have been fused together by mother nature. This results in a weaker structure with different resonant properties. Black doesn’t have any of these problems.” 

And so it is that for Acora’s entry-level speaker in the top SR Series, the $18,750 SRB, Val Cora built a 2-way, ported, brace-free, stand-mounted speaker with a non-diamond-coated beryllium tweeter, a 5.9″ mid/woofer, and a modified 4th-order crossover, all handsomely enclosed in a lustrous black granite cabinet. Yet, as you’ll see, this speaker doesn’t just reflect its designer’s technical orientation; it manifests his very nature.

The Uncompromising Speaker

Just as Val Cora doesn’t compromise on his speaker designs, his SR Series speakers don’t compromise on sound quality. They tell the truth of what’s on the recording, and nothing but. They’re among the most revealing speakers I’ve ever encountered, but there’s no sugar coating. Speakers for the “As You Like It” crowd, these aren’t.

Like all ultra-revealing speakers, the SRB demands an immaculate setup. Don’t even think about cheaping out on cables or amplification. Even among expensive, reference-class options, you’ll want to choose wisely. Cardas cables, for instance, are known to be full in the bass. This is a fortuitous characteristic in many setups, but I found the Cardas Clear a might too fulsome for the Acoras, which, despite their size, are by no means bass shy. I was happier with my standard Empirical Design speaker cables, which are more neutral.

And while I got generally good results with my CH Precision I1 integrated amp, I could not eradicate a persistent shrillness in the lower treble. This is not a characteristic of the amp nor, as I was to learn, of the speaker; rather, it was a less than ideal pairing.

Since Cora voices and exhibits his speakers primarily with tubed gear, I thought it sensible to borrow some to see what would happen. And because the speakers thrive on neutral associated equipment, I sought out two tubed components that JV had recently highlighted as some of the most neutral such products he’d encountered: the Audio Research Reference 160S stereo power amp and Reference 6SE linestage. A call went out to Dave Gordon at ARC, and before I knew it, my friends at JS Audio in Bethesda, Maryland, had provided me samples of these luscious components. The ARC duo worked wonders on the shrillness I’d previously encountered.

When it comes to placing the SRB, some exactitude is required. You’ll want to give these speakers a wide stance, with plenty of distance between them and only a touch of toe-in. That said, the speakers are surprisingly versatile when it comes to distance from the wall behind them. That is, they’re equally amenable to being well out from that wall or in a room that forces them closer to it.

Of course, you’ll need stands—and not just any stands. Acora makes two that are specifically designed for the SRB. In my view, using these, as opposed to generics, is mandatory. To perform as intended, the SRBs need to be tightly coupled to the floor. The Acora stands do that.

The two models are the steel-and-granite SRS-M ($3125) and the significantly heavier, all-granite SRS-G ($6250). Normally, I would have gone for the full-granite option, since Cora told me in no uncertain terms that it sounds better. However, the all-granite stands have a slightly broader base than the metal versions, and that would have conflicted with my media console. This review, then, is based on the speakers being placed atop the SRS-M stands. It’s nice to know that, space and budget permitting, even better sound can be wrung from the SRS by using the SRS-G stands.

After you get all this sorted out, you’ll want to run in the speakers for a long spell before considering them broken in. Anything less than 200 hours, and you’ll hear a paucity in the treble. Don’t worry; it goes away.

Once everything is right, the little SRB dazzles with amazing feats. Play a good piano recording—I typically use Michael Wolff’s 2am—and you’ll marvel at how much slop you’ve been hearing from other speakers. Listen to any good jazz-bass recording and you won’t believe the deep, powerful, punchy, detailed lows you’re getting from such a compact design.

This low-end resolution extends to pop recordings, as well. On Kacey Musgrave’s “Slow Burn,” there’s an extremely subtle bass line that accompanies the guitar through the opening verse. I never heard it before I had the SRBs in my system. That’s the sort of musically meaningful material the SRBs unearth. Indeed, try them with any familiar recording and I dare you not to hear some detail—or be better able to distinguish and follow an obscured musical line—that had previously gone unnoticed.

You’ll also get a more than credible 3-D soundstage, even when the speakers are less than a foot from the wall behind them. As for imaging, it’s as superb as you’d expect from a well-sorted, two-way mini-monitor with an enclosure that’s literally hard as a rock.

Vocals? You’re going to hear every element of the singer’s instrument. Try Satchmo on “St. James Infirmary.” Everything that makes him singular, from tone to style to subtle inflections, is laid bare. Or put on Tracy Chapman having her inimitable way with a live rendition of “Stand by Me.” Her uniqueness and prowess are overwhelming.

The SRB is also very good at something that eludes many speakers, even those that are otherwise of reference caliber: dynamic tracking. I’m not referring to the ability to play soft and loud, or to transition fleetly from one to the other, though the SRB absolutely does those things, too. What I mean is a speaker’s ability to maintain coherence and tonal balance through varying dynamics. The SRB—and all Acora speakers, in my experience—do this to a fare-thee-well.

At the same time, the SRB’s uncompromising nature means that it’s not for everyone. If there are problems with a recording, you’re going to hear them. For instance, Led Zeppelin’s “Black Dog,” no matter the version, is unremittingly thin. The SRB does nothing to hide this fact. Mind you, the Acora doesn’t exaggerate flaws in source material; it just doesn’t disguise or compensate for them.

Which makes it worth noting that the SR Series is not the only model line Acora offers. The company recently introduced the QR Series. Each QR model is identical to its SR counterpart save that it’s made of quartz rather than granite. You can even get them in colors other than black! Those are compromises, true, but Cora was sanguine about them because the QR Series is more forgiving yet retains 95% of the SR’s sound quality. QR models are also 20% less expensive than their granite counterparts.    

Which one is right for you? If you’re willing to give up that 5% of the SRB’s performance for a more forgiving presentation, the QRB could have your name on it. But if it’s uncompromising performance you seek from a compact, stand-mounted speaker—the ultimate in resolution, dynamics, imaging, and musically relevant detail—the Acora SRB should be on your must-audition list.

Specs & Pricing

Type: 2-way bass-reflex standmount
Drivers: 5.9″ sandwich paper cone midrange/woofer, 1″ beryllium dome tweeter
Enclosure: High-polish, natural black granite
Crossover frequency: 3.3kHz
Impedance: 8 ohms
Recommended amplifier power: 10W–150W
Sensitivity: 86.5dB/1W/1m
Frequency response: 43Hz–35KHz
Dimensions: 9″ x 13″ x 11″
Weight: 58 lbs. each without stands
Price: $18,750/pr.

ACORA ACOUSTICS
165 Milner Ave,
Scarborough, ON
Canada
M1S 4G7
acoraacoustics.com
(647) 812-3933