Let me get something out of the way: this is not a review for everyone. The Treble Clef Audio TCA‑M loudspeaker will have many readers shaking their heads in disbelief the minute they learn the price: from $103,900/pair in the United States and €93,000/pair in Europe. Nor is this review for those fixated on traditional passive loudspeakers or those who might shudder at the TCA‑M’s unconventional appearance. The TCA‑M isn’t just expensive; it’s an active design that’s audaciously sculptural in appearance and, therefore, divisive in more than one way.
But if you’re not put off by the TCA‑M’s price tag and you’re curious about what a no-compromise active loudspeaker can truly achieve and you have a zest for radical design language backed by serious engineering, this review is for you.
Description
The TCA‑M is a three-way loudspeaker system that combines proprietary acoustic engineering with visual design courtesy of the company’s founder, Ole Siig, who described its creation to me as a “passion project.” It’s built in Denmark in very limited quantities. Buyers can customize various aspects, such as the color and finish of what I call its aluminum “spine” (because it forms the backbone of the speaker); the wooden cups that surround the bass drivers; the super-sturdy base; and probably other elements, too. You can see options on the website or ask directly for quotes, but if you go custom, the price is likely to increase.
But you can’t customize the elements that affect the sound; driver-wise, you’ll always get a 1.1″ ring-radiator tweeter from Denmark’s Scan-Speak, a 5″ midrange driver also from Scan-Speak, and, nowadays, two 12″ woofers from Acoustic Elegance, which is based in the United States. I say “nowadays” because the 12″ woofers constitute a change from the TCA‑M’s original design, which employed Acoustic Elegance 10″ drivers. That’s how my review pair was configured and why I used the word “original” in this review’s title. According to Siig, the woofer-size upgrade didn’t change the loudspeaker’s voicing, only its bass-output capability (i.e., how loudly the speaker can play), which means newer models with the 12-inchers can play louder than the original version I’m writing about. That said, I’ll point out now that my review pair played loud enough. Siig also said that bass extension wasn’t affected—the TCA‑M has always been rated down to 16Hz when played in a room.
A digital signal processing (DSP) engine built into the solid-aluminum base handles crossover duties and frequency-response tailoring. The TCA‑M can accept line-level analog a balanced input (XLR). Analog signals are digitized by a dual-range, 32-bit floating-point analog-to-digital converter (ADC). This arrangement provides for an exceptionally high signal-to-noise ratio, high dynamic range, and precise conversion accuracy, Siig says. Digital connectivity options comprise AES/EBU (XLR), coaxial S/PDIF (RCA), or ethernet (RJ45) via Dante, a networking platform for delivering lossless audio over multiple channels. The digital stream gets divided into three frequency ranges, with steep crossover slopes at 2400Hz for the midrange to the tweeter and 200Hz for the woofers to the midrange. Since all crossover manipulation is done digitally, it’s not only possible to meld the drivers’ outputs in terms of amplitude response but also to time-align the drivers without penalty—this can’t be done easily, or without compromise, with a traditional passive-loudspeaker design.
Also built into the base are separate power amplifiers from Pascal, another Danish company—one for each frequency range, with a total output power of 1500W. The active design means you don’t need external amplification, but it does mean you have to plug each TCA‑M into the wall. And your analog or digital source needs to have its own volume control, since there’s no way to control volume on the TCA‑M itself. Nor is streaming built in. This isn’t a knock against the TCA‑M—it’s just to say it’s been designed as a serious audiophile active speaker, not an all-in-one lifestyle solution.
It’s hard to say for sure, but I suspect the most common use case will involve the analog input, because it’s quite easy to find an analog preamplifier (with or without built-in streaming), since this type of component is so common. That’s how I used the TCA‑M review pair for this writeup. Less common are preamplifiers with a digital output configured with a volume control, though they’re out there. In the future, I plan to revisit the TCA‑M review pair using one or more of the digital inputs.
Also on the base, but on the top, dead-center near the front, is a small touchscreen that allows for input-type selection, gain adjustment (to accommodate varying analog-source levels), and equalization-curve selection to match the speaker to room size and acoustics. The TCA‑M has several pre-programmed curves—Flat, TCA‑M, TCA‑M Large, TCA‑M Small, Toole (after famous loudspeaker researcher Dr. Floyd Toole), and Harman (after the company Harman Industries, where Toole worked for about two decades and continued his research), with an option to program more.
You can also specify if the speaker is to reproduce the left or right channel when used with a digital source; for analog hookup that’s irrelevant, since channel allocation is determined by which output jack on the source component the speaker is connected to. When connecting digitally via AES/EBU or S/PDIF, only one speaker gets connected to the preamp—the other connects to its partner with a digital umbilical that Treble Clef Audio provides. Dante hookup requires two ethernet cables.
Although the drivers, amplifiers, and DSP engine aren’t made by Treble Clef Audio, every other part is custom for the TCA‑M and is either made at the Treble Clef Audio factory or at local suppliers, which undoubtedly accounts for some of the TCA‑M’s high price. The DSP programming, acoustical design, and other innovations, while not radically different from some other loudspeakers I’ve seen, are all courtesy of Siig.
One of Siig’s acoustic-design goals was to provide as unobstructed a wave launch from each driver as possible, which is why there’s no traditional box-like enclosure. Instead, the TCA‑M has the spine I mentioned before, in the shape of a treble clef. The drivers attach to the spine, and the spine is anchored in the base. This is not just for looks—it has sonic benefits. On some side areas of the spine, clear acrylic pieces are attached that fill in openings. Those probably don’t provide any acoustical benefit, but they do enhance the appearance.
Both the tweeter and the midrange have grilles for protection, though the tweeter’s grille is a permanently affixed metal mesh, and the midrange’s grille has cloth on a round wood frame with magnets for attaching it to the frame of the driver. The best listening is with the midrange’s grille off, though.
Those two drivers are attached to tapered tubes. These have no front edges to create diffraction as the drivers’ soundwaves propagate. The midrange’s tube does a little more, though—its inside is hollowed out, with three stages of internal damping to absorb the cone’s rearward radiation so it doesn’t bounce back and interfere with the driver’s frontward radiation. This isn’t a new invention: tapered-tube loading was originally developed by Laurence Dickie when he designed Bowers & Wilkins’s legendary Nautilus loudspeaker.
The rearward radiation of the woofers’ cones gets dealt with differently, using a form of loading that Siig calls a Folded Dipole. He has patented this design, which can be considered a hallmark of the TCA‑M.
It’s hard to see in photos, but the woofers face each other, placed mere inches apart. There’s a large slot in the front from which the air vents when their cones move. But two aspects of the design are less obvious. Between the two woofer cones is a single metal ball, placed there to take up a precise amount of air space so that Siig’s Folded Dipole bass system works properly. More importantly, the ball is also there to mechanically connect the two woofers’ heavy magnet systems into a single force-canceling arrangement. This eliminates physical vibration and resonances from the two opposing diaphragms. Around back, each cup in which each woofer is placed has a slot, so the rear output of the waves from the woofers is routed out the back of the speaker.
All told, then, the TCA‑M delivers the full output of the woofer cones into the room, as opposed to losing all or most of their rear output, as happens with a woofer (or woofers) working in a traditional sealed or vented enclosure. Siig expressed pride in this aspect of the design, which preserves all the acoustical energy produced by the TCA‑M’s woofers. He said this is vital to the speaker’s performance. So are the slots that direct the sound forwards and rearwards. Because these soundwaves are out of phase (i.e., opposite to each other), they create an acoustic null (i.e., cancellation) to the speaker’s sides, which Siig told me makes the speaker more room-friendly by diminishing bass modes. More on that below.
I could go on about the appearance and construction of the TCA‑M, but last fall we visited the company and subsequently produced two videos that are now available on our YouTube channel—“Treble Clef Audio’s TCA‑M Loudspeaker—Danish, Active, Expensive, and Dazzlingly Original” and “How the Treble Clef TCA‑M Was Designed for Sound—and Became a Sculpture Too.” These videos convey the unique aspects of the speaker better than words can.
What those videos and the pictures accompanying this article can’t convey is how substantial of a speaker the TCA‑M is. Each speaker stands a hair over 53″ tall and weighs about 200 pounds, thanks to the beefy woofers and thick, solid-aluminum construction of the spine and base. Pictures and videos can also make the TCA‑M look dainty, as if it could be pushed over fairly easily. In fact, I found that the heavy base and the structure’s strength make the TCA‑M more stable than many box-type speakers. While the TCA‑M has a skeletal look, it’s something of a beast.
It’s also quite durable, something I can’t say about box-type speakers with, say, a high-gloss finish, which can be damaged easily. The aluminum pieces are pretty much dent-proof. The Nextel coating that’s standard for the base provides a suede-like finish that can withstand some abuse. I suppose you could mark up the wood pieces, but since they have an artisanal look, I’m pretty sure they’re much easier to repair than a high-gloss painted finish would be.
The photos and videos also don’t convey how a pair of TCA‑Ms actually looks in a room. Undoubtedly, the design is polarizing and, therefore, will have its detractors, especially people who can’t wrap their heads around not having some sort of box-type enclosure. But not everyone wants a pair of boxes in their room. I’ve had the Treble Clef speakers in my living room, which measures about 16′ × 18′, for months. They’ve been placed prominently, and the reaction among family and guests has been 80% positive, with most of them seeing the speakers as much as art pieces as sound producers. Unlike some speakers that have inhabited my living room, my wife hasn’t been itching for them to leave, which says something.
Setup
The TCA‑M review pair arrived during a snowy time in January. Thankfully, each speaker came well packed in a large wooden crate that kept snow out and made setup relatively easy. I recruited Chris Chitaroni and Jorden Guth from our video team to help. We brought the crates to my front door one at a time, undid the clips that held the crate walls in place, carefully removed each crate wall so it didn’t slam against the cloth-protected speaker, undid the locking mechanism at the base of the speaker that kept it from moving around in the crate, and rolled the speaker out. Each speaker arrives with casters inserted into the base that you replace with thick aluminum footers once you have the speaker where you want it to be. With this arrangement, installing these large speakers can be accomplished by a single person; but with the inclement weather, I was glad to have Chris and Jorden helping me.
We placed the TCA‑Ms in pretty much the same positions other speakers have occupied along one of the 16′ walls in my living room. I only shifted them around slightly afterwards. They ended up 8.5′ apart, tweeter to tweeter, with 20″ to the wall behind. Treble Clef Audio supplies all the necessary cables to connect the speakers to an analog or digital source and to the wall outlets, so I used their XLR-terminated interconnects from Pig Hog and their power cords, which have Neutrik connectors on the speaker end.
As mentioned, I went strictly analog for this setup, but over time used two streaming preamps: first a Simaudio Moon 791 and later an Eversolo DMP‑A10. The sonic results were similar with streamed digital playback. The DMP‑A10 doesn’t have a phono stage but the 791 does, so I used my Denon DP-3000NE turntable only with the Moon 791.
Sound
Siig had recommended that I first focus on the three TCA‑M equalization curves, so I started with the one suited for the largest rooms: TCA‑M Large. It only took playing a couple of familiar tracks to realize that these speakers could generate extremely deep bass. But the speakers were also overloading the room so badly that the bass was obscuring the midrange and highs. This was obvious on bass-heavy tracks, but also on tracks with decent-but-not-overwhelming bass, such as Bruce Cockburn’s “Pacing the Cage,” from The Charity of Night (16-bit/44.1kHz FLAC, True North Records / Tidal), a song I often use for equipment reviews. Rob Wasserman’s bass was being reproduced too loudly and was obscuring Cockburn’s vocal and guitar.
I next tried TCA‑M Small, which noticeably diminished bass output, both in terms of extension and level, allowing the frequencies above the bass region to pop more. As a result, Cockburn’s voice and guitar were more apparent. Wasserman’s bass was still noticeable but no longer the center of attention. I could have lived with this setting, but of course there’s straight-up TCA‑M, which I found lands pretty much in the middle. With this setting, bass extension was as deep as it was with TCA‑M Large, but the volume level in the bass region wasn’t as high, so that bass was better balanced with the midrange and highs. Those frequencies did not pop as much as with TCA‑M Small, but I appreciated the deeper bass I was now hearing. Not only that, the TCA‑Ms went deeper than any speakers I’ve had in that room, including the Arendal 1528 Tower 8s, a pair of very large passive floorstanders, each with four 8″ woofers, which were set up in pretty much the same locations. As a result, Treble Clef Audio’s claim that the TCA‑M can produce bass right to the bottom of the audioband (20Hz) in a room is credible. This is also proof that active speakers can bend the rules in ways passive speakers simply can’t, particularly in the bass.
With bass output balanced for my room and preferences, I could get a better measure of the TCA‑M’s sonic signature. My assessment might surprise some people, because its wild appearance doesn’t translate into a wild sound—though it does have some defining characteristics I’ll get to. Rather, from the lowest lows to the highest highs that it reproduces, I’d call the TCA‑M a neutral transducer, which means it doesn’t favor one part of the frequency range over the others.
For example, when I played “Dreams” from Fleetwood Mac’s Rumours (Warner Bros. BSK 3010), which is one of my regular test LPs, I heard Mick Fleetwood’s drum sounds thunder in the room with, I believe, every bit of low-frequency energy that the album has in its grooves—but no more. Stevie Nicks’s vocal, which I’ve always believed to be mixed just a touch too low in level, sounded exactly that way through the TCA‑Ms. In other words, the speakers weren’t adding or subtracting anything. What was also noteworthy was the way I could distinguish Fleetwood’s drums from John McVie’s bass, with the word “articulate” springing to mind as I tried to describe what I was hearing.
Later, to validate my long-term listening impressions about the bass presentation and its relation to the frequencies above, I streamed “Birds” from Dominique Fils-Aimé’s Nameless (24/88.2 FLAC, Ensoul Records / Qobuz). This track has been overplayed in audiophile circles—I haven’t been able to attend a hi-fi show in years without hearing it being played over and over in several rooms. But it’s exceptionally well recorded and still a good way to test your stereo system, since Fils-Aimé’s singing voice sounds completely lifelike and the bass has both weight and extension. Re-listening confirmed to me that in my room, the TCA‑M setting was the correct one, as the bass on this track sounded both deep and powerful, but in perfect balance with the midrange and highs. Notwithstanding Treble Clef’s claim that the TCA‑M’s unique bass implementation reduces room interaction, I could hear subtle modes; the design doesn’t completely eliminate mode-type issues. However, I believe these subtle modes could be tamed with judicious equalization specific to those frequencies, something the TCA‑M’s DSP engine supports. I plan to experiment with this in the future.
With “Birds,” “Dreams,” “Pacing the Cage,” and other tracks I listened to over the months that the speakers were here, two other strengths emerged: openness and imaging.
Openness has to do with how well a speaker projects sound into the room. In a good stereo setup, the sound will obviously emerge from the two speakers, but there should be no telltale signs that draw your attention to the speakers themselves; that’s usually a sign of unwanted resonances or distortion. The TCA‑M provides that openness—sound springs out of it—which no doubt has a lot to do with its skeletal, diffraction-reducing design and the absence of enclosure-based resonances.
Imaging has to do with the precision of aural images of the musicians on the soundstage, providing of course that this is a characteristic of the recording itself. Precise imaging might seem at odds with openness—you’d think an open-sounding speaker would have diffuse imaging—but when playing “Birds,” the TCA‑Ms rendered Fils-Aimé’s voice rock-solid in the center, without spreading out laterally to the speakers themselves. Ditto for Cockburn’s on “Pacing the Cage” and Nicks’s on “Dreams.”
Another good example is what I experienced when playing “Spanish Steps,” the instrumental opening track from Van Morrison’s Poetic Champions Compose (16/44.1 FLAC, Mercury Records / Qobuz). The openness I described was apparent again, with Morrison’s sax placed solidly at the front-center of the soundstage, completely divorced from the speakers. Just as importantly, the instruments surrounding the sax were floating freely in the soundstage, clearly focused left-to-right and front-to-back, displaying the good sense of stage depth in this recording.
And while the bass is not something I often comment on with this track (unless it’s to criticize its inherent lack of extension in the recording), when played through the TCA‑Ms, it sounded so tight and immediate that I sat right up the first time I heard it—and then played it again and again to make sure I wasn’t imagining something, which says a lot about Siig’s unique bass implementation.
But I have to finish by mentioning one song I could not fully get a handle on through the TCA‑Ms: Emmylou Harris’s “Orphan Girl” from Wrecking Ball. The album was produced by Daniel Lanois, and the best streamed version I’ve found is on Tidal and Qobuz in the Wrecking Ball (Deluxe Edition) release, in 24/44.1 FLAC.
I’ve played that version dozens of times over the past few months, and just before writing this I streamed it again to refresh my memory. As always, Harris’s voice came through with striking clarity. Above it, the jangly, high-frequency percussion floated so effortlessly in space it seemed to form a halo around the soundstage. I haven’t written much about this speaker’s tweeter performance, but suffice it to say it’s extended, clean, and free of edginess. Clearly, this is a very good tweeter, well implemented. The overall presentation was open and precise in its imaging, consistent with what I’d heard from the TCA‑Ms before.
The puzzle lies in the bass—specifically, the deep, resonant hand-drum sound from U2’s Larry Mullen Jr., which anchors the track. As I mentioned earlier, the TCA‑Ms delivered deeper bass than any other speakers I’ve had in this room, and in doing so they revealed ultra-low frequencies I hadn’t heard in this song before, just as they’d done with other songs. But unlike other speakers I’ve used in this room—such as the Arendal 1528 Tower 8s, set up in nearly identical positions—the TCA‑Ms didn’t provide the same upper-bass punch; this is something I didn’t notice with the other tracks. This difference wasn’t subtle. Through the TCA‑Ms, the track sometimes felt like a darker, weightier, alternate version of itself.
With most other songs I played, the TCA‑Ms’ greater low-end reach simply added depth; with this song, it altered the entire character of the bass. I can’t pinpoint why this particular track came across so differently. This left me wondering what the “right” presentation actually is: the heavier, more brooding version the TCA‑Ms delivered, or the punchier, more forward sound I’d grown used to with the Tower 8s and other speakers. I wonder if perhaps the TCA‑Ms’ ability to dig so deep in my room is shifting my perception of the entire bass region, but I still really don’t know.
Coincidentally, just before finishing this review, I saw Daniel Lanois in concert and later had a chance to speak with him briefly. I would have loved to ask how the bass range on this track is really supposed to sound, which is something only the people behind the recording could know. But this wasn’t the time or place for that conversation, nor would it be fair to ask Lanois to recall the sound of something he recorded 30 years ago. For now, what the most faithful rendition of this recording is remains a mystery. At least in my room, whatever Siig is doing in the bass does result in a rather distinctive sound.
Conclusion and continuation
What’s not a mystery is that Treble Clef Audio’s first (and presently only) loudspeaker is expensive, wild-looking, well-built, and technologically advanced. All that would be for naught if the speaker didn’t sound good. No fear there—it certainly does. Its strengths include true full-range sound, meaning bass down to 20Hz and highs at least up to 20kHz; a free and open sound, which, as I mentioned above, probably has a lot to do with its unique construction; neutrality through the entire audioband, provided you have the bass dialed in correctly; clarity across the whole audioband, meaning details never get obscured; and an articulate, impactful character of the bass region that deserves further investigation by yours truly and, perhaps, you—that’s if you get a chance to hear a pair.
Clearly I’m not done with the TCA‑M yet, since there are many things left to fiddle with. If you’ve read this far, you surely realize that there’s more to come.
. . . Doug Schneider
das@soundstage.com
Associated Equipment
- Streaming preamplifiers: Simaudio Moon 791, Eversolo DMP‑A10 (both with stock power cords)
- Turntable: Denon DP-3000NE with DL-103o cartridge (stock power cord and analog cable)
- Analog speaker interconnects: Pig Hog
- Speaker power cords: Treble Clef Audio supplied
- Power distributor: Shunyata Research PS8 with Venom HC power cord
- Acoustical treatments: BXI Sound Absorber panels (20), Tönnen Sound panels (2)
Treble Clef Audio TCA‑M active loudspeaker
Price (per pair): US$103,900, €93,000
Warranty: Seven years, parts and labor (with registration)
Treble Clef Audio ApS
Møllehaven 12B
4040 Jyllinge
Denmark
Website: www.TrebleClefAudio.com