The Fifth Element #85 Page 2

The SL mid/woofer, which debuted in 1998, was designed by ATC's founder, managing director, and head of engineering, Billy Woodman, who is also responsible for completing the industrial-design makeover. The speaker's tweeter and crossover are the work of R&D/transducer engineer Richard Newman.

The SCM19 v.2 measures 17.1" high by 10.3" wide by 11.7" D, and weighs 39 lbs. It's a handsome, solid, extremely hefty speaker available in satin-finished Cherry or Black Ash veneers. On the rear panel are two pairs of uninsulated binding posts for biwiring (jumpers provided). The SCM19s arrived packed in sturdy double boxes (one speaker per box: they're heavy) with molded packing blocks, cloth drawstring bags to protect the veneers, and an owner's manual. They're warrantied for six years.


ATC states that the SCM19 v.2's frequency response is 54Hz–22kHz, –6dB; its sensitivity is a lowish 85dB/W/m, its nominal impedance 8 ohms. They also claim a maximum SPL capability of 108dB; a flat impedance curve that presents an easy load to amplifiers (they recommend 75–300Wpc); that the woofer's motor assembly weighs 20 lbs; and that the drivers are pair-matched to ±0.5dB.

Why Sealed?
In a wide-ranging phone conversation, Ben Lilly, ATC's manager of R&D, explained the company's different-drummer approach to speaker-cabinet design. Whether an enclosure is vented or sealed, the primary goal is the same: to minimize distortion. Lilly said that it perhaps would be easier to explain why ATC's four entry-level SCM models are not vented than why the larger ones are.

A smaller loudspeaker will have a smaller, lighter woofer, whose lower mass will give it a higher resonant frequency. Because ATC tunes the port in their vented speakers to the resonant frequency of the drive-unit, were they to put a small driver in a ported cabinet, the result, in Lilly's words, would be "a huge lack of control over the drive-unit below the port-tuning frequency."

Using the SCM19's 6" mid/woofer as an example, Lilly said, "A port would offer control down to 35 or 30Hz, but you still have program material below that, which can cause significant motion of the drive-unit and generate distortion." Therefore, ATC uses vented enclosures only in designs whose woofers of sufficient size and weight to have a resonant frequency low enough that the port can control the woofer and avoid any overexcursions in the bottom octave.

At some point in my conversation with Lilly, a light bulb went on over my head. I had finally learned why the BBC LS3/5a and its descendants are sealed-box designs: The LS3/5a's 4" mid/woofer is too small, and therefore too light, to allow its bass to be controlled by a port.

The SCM19 v.2 decisively strode ahead of the SCM7 v.3 in seven-league boots in two areas: resolution and bass extension. The SCM7 had no distortion that I was aware of, but the SL driver in the SCM19 was so much more revealing that it was not funny. Hand in hand with that was much more bass impact than I ever would have imagined possible from a glance at ATC's published specs of these speakers' –6dB points: 60Hz for the SCM7, yet only 54Hz for the more-than-twice-as-expensive SCM19. That was not what it sounded or felt like.

After sending the SCM7s on to John Atkinson to be measured, I borrowed a pair of 11-ohm Spendor LS3/5a minimonitors (ca 1991), for a refresher listen. Therefore, my immediate comparison was not of the SCM19 v.2 with the SCM7 but with an older speaker with similar aspirations. Compared to the vintage LS3/5a, and to my memories of the ATC SCM7, the SCM19 exhibited an arresting increase in resolving power.

One of the first things I listened to was the CD version of the Cypress String Quartet's recording of Beethoven's Quartet 12, Op.127 (3 CDs, Cypress 5637890958). It was spellbinding. If you want to hear evidence that we live in a golden age of string-quartet playing, buy the single CD that includes this work. The slow movement of Op.127—and, later, Alexandre Thauraud's CD of encores, Autograph (CD, Erato 34137; highlighted in my April 2014 column), caused me to sum up: "industrial-strength beauty."

The SCM19 v.2's nearly-best-in-class resolving power (Vivid Audio's four-times-as-expensive Oval B1 still pips it there, I think) shone on my longest-serving test track, "Easy to Love," from Ella Fitzgerald's The Cole Porter Songbook, Volume Two (CD, Verve 821 990-2). The pulsing of her vibrato as the last word of the song trails off was as present and full as never before. But credit for that must be shared with Parasound's Halo CD 1 used as a transport, Grace Design's phenomenal m905 DAC-linestage, and ATC's own P1, a 150Wpc stereo power amplifier ($3499), for which I have no room left to discuss this month—as well as with a wealth of power accessories from Shunyata Research and cables from Cardas.

Another sit-up-straight moment came at the end of Holst's The Planets, in the venerable and, in my opinion, never artistically surpassed 1970 recording by William Steinberg and the Boston Symphony, which I first heard ages ago from the foil-jacket LP, which I still possess. Or rather, it still possesses me. I also have it on a 1987 Deutsche Grammophon Galleria CD (419 475-2), now available only as an MP3. DG currently offers this recording coupled with a well-regarded Steinberg-BSO performance of Strauss's Also sprach Zarathustra, for all of 12 bucks (DG Originals 463 627-2). It was not, however, Steinberg's justly fêted Mars that stiffened my spine, but the quiet of the final movement, Neptune, with the women of the New England Conservatory Chorus. I heard subtle low-level detail in the orchestration that I never have before. (HDtracks offers a 24-bit/96kHz download of this recording that I have yet to hear.)

Other standout listening experiences included Sir Adrian Boult and the London Philharmonic's recording of Vaughan Williams's Tallis Fantasia and A London Symphony (CD, EMI CDC 7 47213 2); Knut Nystedt's Immortal Nystedt. with Øystein Fevang and Ensemble 96 (SACD/CD, 2L 2L-029-SACD); pianist Alan Feinberg's Basically Bull (CD, Steinway & Sons 30019); and Elvis Costello's All This Useless Beauty (CD, Warner Bros. 46198-2).

To sum up
ATC's SCM19 v.2 delivers bass extension, detail, fullness, and presence to such greater extents than its smaller sibling, the SCM7, that I consider the $2200/pair more it costs to be more than fully justified. Indeed, I consider the larger speaker to be so much the better value at $3699/pair that I fear that for many listeners, buying the SCM7 would be a false economy. The SCM19 might be all the speaker most people will ever need. Well done. Highly recommended.

Riedel Microfiber Stemware Drying Cloth Riedel, an Austrian maker of glassware established in 1756, specializes in stemware for drinking wine ( Riedel pioneered the controversial notion that different types of wine should be served in glasses of widely varying sizes and shapes. Riedel's Burgundy Grand Cru glass (which in theory can hold 37 ounces) is in the collection of the Museum of Modern Art, in New York City. That capacity figure is rather misleading, because nearly all wineglasses are designed to be filled only halfway or even less, so that the wine's bouquet can develop. (Small glasses for Port are one exception.)


Tiring of the way general-purpose dishcloths and tea towels leave smudges on wineglasses, I searched for a drying cloth designed for stemware. It didn't take me long to learn that Riedel sells a high-tech solution: a micro-microfiber cloth made in China. I bought one, and was so impressed by the resulting sparkle of my glassware that I bought two more as gifts for friends.

Riedel's drying cloth comes with detailed instructions and cautions, necessary because the cloth absorbs water so well that it quickly becomes very "grippy." Therefore, you should never hold a wineglass by its foot and attempt to dry its bowl by turning the foot with one hand while holding the cloth against the bowl with the other—it could easily shatter the stem.

One evening, about to play a CD, I noticed that it was smeared with fingerprints. I carefully washed the disc with Dawn dishwashing liquid, thoroughly rinsed it in running lukewarm water—and then, on a whim, dried it with radial motions of the Riedel drying cloth. I was amazed at how it made the CD's data surface shine. For about $12 from vendors on eBay or Amazon, this is the best CD-drying cloth ever.


Catch22's picture

Well done my man!

remlab's picture

Very enjoyable! And after 30 years, I finally know how to pronounce "Kloss". Hah!

Mikeymort's picture

I loved this article. When I served in the Army during the middle seventies, the barracks where I lived was filled with post exchange acquired gear. Hi wattage receivers and acoustic suspension speakers. I had large Advents and a Marantz receiver. Luckily, one of my roommates had a tubed Dynaco system with A-50 speakers. (What is aperiodic anyway?) We could listen to his system hour after hour with no listening fatigue. I have a similar system today.

John Marks's picture

And so by implication does not have a primary resonant frequency.

Specifically, an "aperiodic" loudspeaker enclosure design can be looked at either as a ported enclosure that has resistance in the port, or, a sealed box that leaks.

While the Dynaco Variovent is the most familiar application, I believe that stuffing the port in the ProAc Tablette with cocktail stirrer straws accomplished the same thing.

Thanks for the kind words. It was fun to ferret out all those old stories. BTW, I asked Winslow Burhoe, who was Edgar Villchur's research assistant on the AR4, what it was like to have Villchur as a boss, and he impishly replied, "I don't know. He was never there."

A priceless moment.


tmsorosk's picture

A very entertaining and informative article.

Well done Mark.

John Marks's picture

I'm John.

corrective_unconscious's picture

It's a coarses for hoarses thing.

ganyc's picture

Hi John,

Nice review. In this case do you think that "fullness" and "presence" equate to warmth? My only experience with ATC speakers was infrequent appearances at RMAF. I don't think I would have described what I heard as warm.



hnipen's picture

Thanks for a great history lesson John :-)

Timbo in Oz's picture

system as a resonant circuit. No?

It was able to help us build good sealed boxes, too. It is possible to build boomy/heavy bass sealed speakers.

JBTWay the KEF b110 has been used in Rb boxes, in the bass-extension stand/tower for the LS3/5A. But even that didn't go particularly deep.

It is possible to get similar results to a sealed enclosure with room-gain, (still with some cone-bounce issues,) by using a critically damped QB3 alignment or even an over-damped alignment.

IME the best kind of Rb enclosure is an 'active' or 'assisted' 5th or 6th-order alignment using an active 2nd order HP filter in the line to the power amp with a little gain. Boost |\__ This almost eliminates the distortion that is visible as cone-bounce, while also limiting motor excursion, and can provide another half octave of extension.

This idea could also help with TL designs which are damned close to Rb's when modelled.

Timothy Bailey

davip's picture

It was back in 1984 that I auditioned new loudspeakers to replace my blowsy Eagle three-ways. I left the demonstrators in the showroom flabbergasted at how the LP that I used left every other cab in their shop a hopeless, farting mess of distortion -- the darling of that year, the Linn Kan, a slate-topped and -bottomed JBE slate speaker, even the Mission 770 with its prodigious 500W bass-handling, its port asthmatically chuffing and wheezing. They regarded it as a challenge to find a speaker in their shop that would play this LP at-all without distorting, let alone sounding good too (and they kept my LP for weeks after too!)

Only one speaker cut it -- the AR18s. I've since become aware that its midband is not what one would call 'revealing', but for rock music it's ideal. Its paper-tweeter is as sweet as butter with vinyl, its one-element crossover is the simplest there is and effectively Active, and where else can you find a loudspeaker little larger than a shoe-box that can bass-lock a 100 m3 room when playing PGIV?

Thank You E.V. (and also for the suspension on which my STD 305M was based)

N.B. Regarding that LP for anyone who wants to test the bass capabilities of a speaker, it's 'Faith' by The Cure, with a six-string bass used throughout -- first track 'The Holy Hour', high-level 31Hz B-string -- that's where acoustic-suspension, sealed-cabinet, 12 db/octave roll-off comes into its own.