TAD Grand Evolution One loudspeaker

Review samples of some new high-end audio products do not grow on trees. They are more like dray horses trouping from one destination to another. After the US premiere of the Technical Audio Devices (TAD) Grand Evolution One (TAD-GE1), a floorstanding speaker from TAD’s Evolution series, at the 2023 Capital Audio Fest, the review pair came to stay with me in Upstate New York for a couple of months before traveling on to the 2024 Florida Audio Expo for another public appearance. After that, they returned to John Atkinson for measuring—then off again on another journey.

The TAD Labs GE1 is a three-way, three-driver design. Up top is TAD’s proprietary Coherent Source Transducer (CST), a 5½” coaxial tweeter/midrange driver. Two matched 7″ woofers fill out the middle of the front panel. On the back are two pairs of speaker taps connected (at the moment) with high-quality jumper cables; those who biwire or biamp are cared for. The GE1 is a bass-reflex speaker; its port fires down. The footers are the usual spiked cones; a set of metal discs is thoughtfully included for those who wish to protect their hardwood floors.

The cabinet stands just shy of 49″ tall, constructed out of 40mm-thick MDF panels and 18mm birch plywood bracing. The visual aesthetic is similar to that of a fine grand piano: sides and back finished in shiny black lacquer, the front kitted out in very handsome, glossy-finished olive wood, similar to the inside rims of some high-end pianos. The cabinet edges are smoothly contoured. The cabinets sit atop an attached combo port/plate (more on this in a moment). Including this platform, each speaker weighs 140lb. This is not a compact speaker, but it is hardly overwhelming in scale. The Grand Evolution One is handsome, with a good shot at a Best of Breed ribbon for its shiny coat alone. The physical appearance and bespoke build quality would enhance any interior decor.

The new TAD GE1 obviously shares technology genes with earlier TAD speakers Stereophile has reviewed, including the CE1TX standmount reviews reviewed by Herb Reichert recently, the Compact Reference reviewed by John Atkinson in 2012, and two earlier members of the Evolution family, the Evolution One and the Compact Evolution One. The TAD Labs Grand Evolution One is priced at $65,000/pair.

From control rooms to living rooms

There’s a dialectic at work in the audio world, one of several, or many. Some companies primarily design for, and sell to, the pro-audio market, including monitoring equipment for studios. Others conceptualize, manufacture, and market wares exclusively for home audio. A few manufacturers, from boutique garage outfits to large international corporations, walk on both sides of the street. Pioneer Electronics in Japan is an example of the latter: In 1978, Pioneer, which had long been associated with affordable hi-fi products, spun off Technical Audio Devices Laboratories (TAD Labs), which focused initially on loudspeakers and drivers meant for use in studios; TAD products were (and continue to be) built in Japan. CEO Shinji Tarutani and Head of Design Toru Nagatani have been with both companies for many years.

TAD’s mission expanded when Pioneer hired loudspeaker designer Andrew Jones, who previously worked with KEF, to design products intended for consumers. The first model Jones designed for TAD, in collaboration with Nagatani, was the big Model One. That model featured a coaxial midrange/beryllium tweeter driver. Although Jones has since moved on, current TAD loudspeakers are variations on this theme. The current US distributor for TAD Labs is Pro Audio Design (hence “TAD via PAD”), headed by Dave Malekpour. Dave has a long history in pro-side design including Augspurger studio monitors, which have utilized TAD drivers.

During a long Zoom conversation, Malekpour shared his views about the back and forth between consumer and pro audio. “What we want in a studio monitor is very different than what we want in a playback monitor. In a studio monitor, we want something that is going to show us all the warts, especially in the midrange where the vocals are. In a hi-fi speaker, we generally want something a little softer in the midrange: We want to show off the music. For example, the Yamaha NS-10 monitors are still widely respected by engineers, but they aren’t something you listen to for pleasure. The design brief for the GE1 was to make a gorgeous loudspeaker—gorgeous looking and gorgeous sounding.”

Coincidences

One of the most prominent technical features of TAD loudspeakers is the use of their own “coincident” drivers. “Coincident” refers to the specific way TAD designs work; the tweeter is nestled snugly within the larger midrange such that the tweeter doesn’t block the center area of the midrange cone. TAD did not invent this approach; that history stretches back to the 1940s, to the development of the Altec Lansing Duplex, which dominated the studio-monitor market in the US. Tannoy’s “Dual Concentric” drivers played a similar role in Europe. When properly engineered, concentric drivers can generate highly coherent, in-phase sound originating from a single point in space, over an extended frequency range.

For the GE1’s Coherent Source Transducer, a proprietary vapor-deposition technique was used to fabricate the beryllium tweeter diaphragm, which is nestled in the center of that 5½” magnesium midrange cone. According to TAD’s specifications, this dual driver, which is isolated in its own cabinet chamber, covers frequencies from the upper bass to the ultrasonic, 250Hz–100kHz.

“The CST driver, being a point-source, has more controlled dispersion than with a domed tweeter,” Malekpour said. “When you listen to the speaker, no matter where you place it, you feel like it’s aimed at you. The phase response is very even. For the listener, what that means is: smooth. No frequency holes. The big issue with a dual-concentric–type driver is the positioning. The two elements, the midrange and the tweeter, are timed by their positioning. The response is exceptionally linear.”

Apart from Tannoy, which still makes concentric-driver speakers, a few other consumer-focused companies take a similar approach. Probably the most prominent is KEF, with its Uni-Q driver array. France’s Cabasse is another; the Cabasse La Sphère loudspeaker uses a four-way concentric driver. And then there’s Fyne, which was founded by several Tannoy veterans.

Considering those sonic benefits, particularly in soundstage and image detail, why don’t all loudspeakers use concentric drivers? Because there are tradeoffs. With coincident drivers, the main challenge is modulation distortion. Diffraction and unwanted reflections are also problems, especially at high SPLs, and magnetic field interactions in the motor can also cause problems. TAD’s CST driver deals with the magnetic interactions by employing a nonferrous conductive ring to cancel the influence of the magnetic flux from one driver on the other. It deals with the acoustical issues by putting the tweeter behind the midrange, time-aligning them to minimize interactions, and setting the crossover point to the lower-frequency driver so that such “modulation distortion” remains below the threshold of detection.

Appealing to the bass

Speaking of crossover points: The specified crossover frequencies for the GE1’s are 250Hz and 1.8kHz. Below 250Hz, that matched pair of 7″ woofers kicks in. TAD, which seems to enjoy creating acronyms and initialisms for their design elements, calls this driver the MACS II (Multi-layered Aramid Composite Shell Second Generation) diaphragm woofer (footnote 1).

The GE1’s bass performance is augmented by acoustic tubing directed down to the reflex port that exits to the floor platform. TAD has a term for this as well: AFAST (Acoustic Filter Assisted System Tuning). In technical notes, TAD describes it this way: “Multiple acoustic tubes with acoustic resistance added to their end surfaces are buried inside the enclosure to effectively suppress standing waves.” When the audio wave exits the cabinet via the port, it encounters two hefty chunks of diecast aluminum, which TAD terms Bidirectional Aero-Dynamic Port (or ADP). These flared metal blocks, which are mounted on a 15mm-thick aluminum base plate, force the port’s output to the front and the rear, blocking it to the sides.

What do these two features accomplish? “It’s not a transmission line, but what is happening there is they take the energy inside the cabinet and push it into the port,” Malekpour said. “It’s almost a funneling system from compression into a horn-loaded port. This filters out some of the potential for noise and gives you a very linear low-frequency exit. The bi-directional movement of energy reduces cabinet motion, and you can also get the speaker closer to a wall than with a rear-firing only port design.” TAD’s low-end frequency response specification for the GE1 is 27Hz. I note my colleague Ken Micallef ‘s comment when he heard this very pair of GE1’s at the 2023 Capital Audiofest. He called it “the deepest, most extended, room-filling and brain-frying low-end I’ve heard outside a recording studio.”

Is this impressive package easy to drive? The published sensitivity is a middling 88dB/2.83V/m, with a nominal impedance of 4 ohms. “They do like power,” Malekpour said. “They are not a highly sensitive, superefficient speaker. I like it when the amplifiers have some headroom.” In my auditions, I used my VPI analog front end, Bricasti digital, and McIntosh amplification, all familiar from everday listening and several previous reviews.

Rooms of one’s own

Both TAD Grand Evolution Ones arrived strapped to a single wooden pallet, packed in two single-layer cardboard boxes. When I asked about the lightweight packaging, I was told that these boxes were meant for one-time use and that more serious crating was in the works. TAD, apparently, is catching up with increasing demand for their products as their distribution in the US expands after a fallow period.

I trundled the speakers in their boxes into the front hall of our house and unpacked them there before hauling them to the large Victorian double parlor that holds my Downstairs System. I wanted to hear how a substantial three-way floorstander would perform there, replacing the smaller, two-way standmount Harbeths normally placed on either side of a fireplace.

Footnote 1: You can think of aramid as generic Kevlar.

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Technical Devices Laboratories, Inc.
Bunkyo Green Ct. 2-28-8, Honkomagome
Bunkyo-ku, Tokyo 113-0021
Japan
info@padhifi.com
(781) 982-2600
padhifi.com

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