The Fifth Element #83 Page 2

When first set up, the ATC SCM7 v.3s sounded to me like promising speakers that definitely needed breaking in. Between lots of listening to the Archiv boxed set, sifting through a treasure trove of Mobile Fidelity Sound Lab SACD reissues, and keeping up with new releases, as well as daily thwackings with Ayre Acoustics' Irrational! But Efficacious System Enhancement CD Version 1.2, over the course of weeks, the SCM7's treble blended better with the midrange, and the sound as a whole opened up and calmed down. All of my substantive comments refer to the end state the SCM7 reached.

It was immediately apparent from the first application (at a moderately but not insanely high volume) of the Irrational! But Efficacious disc's "Full Glide Tone," which begins at 5Hz (!), that the SCM7 was, for its size, bombproof. The woofer's excursions at subsonic frequencies were just plain huge. And while no sound emerged, the lack of sounds of distress or mechanical noises was most impressive.

The woofer behaved as you might hope a 5" woofer with a magnet structure the size of its cone and a motor weighing 7 lbs would. A DIY speaker-designer friend witnessed one administration of the "Full Glide Tone" and spontaneously exclaimed his amazement at the robustness of the woofer's excursion, and at how low (especially for a sealed-box design), the woofer began to actually make sound.


The SCM7 deftly handled the "Channel Identification" and "Channel Phasing" tracks of Stereophile's Test CD 2 (Stereophile STPH004-2). Image specificity was excellent, and the difference between the in- and out-of-phase segments was as great as I've ever heard. I do have to call the SCM7's reproduction of JA's low electric-bass notes "respectable" rather than "convincing," and nowhere near flat at 41Hz, the frequency of the instrument's low open-E string. On the bass guitar tracks, the larger woofer, larger cabinet, and ported design of the Opera Callas that I reviewed in August 2013 carried the day. (I relied on aural memory; the Callases were shipped to JA before the SCM7s arrived.) However, the higher-frequency reaches of the "Full Glide Tone" indicated that the SCM7 had a noticeably more extended top end than the Callas.

The SCM7 offered pinpoint imaging. "Easy to Love," from Ella Fitzgerald's The Cole Porter Songbook, Volume Two (CD, Verve 821 990-2), was a prime example—and if you think that judging imaging with a monaural recording is cheating, then Esa-Pekka Salonen and the Philharmonia Orchestra's live recording of Schoenberg's Gurrelieder was just as impressive (SACD/CD, Signum SIGCD173). There were also excellent retrieval of detail in the frequency and time domains (the acoustic guitar in the title track of Joni Mitchell's Court and Spark [gold CD, DCC GZS 1025]); low distortion (the mechanical noises made by the ancient pipe organ played by Helmut Walcha in the Archiv set were quite apparent), and, overall a naturally musical sound. I listened to Roxy Music's Avalon (CD, Virgin 8 47460 2) straight through, three times in a row.

Especially rewarding was track 1 of Stile Antico's The Phoenix Rising (SACD/CD, Harmonia Mundi 807572), William Byrd's Ave verum corpus, precisely because the SCM7's lack of extension below the midbass was a nonissue with this recording of a cappella choral singing, allowing the ATCs to "romp like the mind of God."

When he measured the ATC SCM11, JA mentioned that "its measured behavior suggests it will work better when listened to fairly close," by which he was specifically referring to the SCM11's non-aggressive treble response and its lack of high-treble dispersion. As chancy a proposition as it may be to judge a new speaker against memories of the sound of a different speaker of the same family, I did get the impression that ATC's new, in-house–made tweeter was more extended and more linear in response than the tweeter I'd heard in the SCM11—or that the SCM11's crossover voicing had made it sound that way.

You can't have everything in a speaker that costs only $1500/pair. Obviously, a sealed-box speaker with a 5" woofer won't get anywhere near flat response at 41Hz (low E on an electric bass) or 32Hz (low C on a pipe organ) or 27.5Hz (low A on a piano). Furthermore, while the updated SCM7 has impressively low distortion—actually, it had no distortion that I could hear, which I attribute to the robustness of its woofer—it didn't match the resolving power of much more expensive two-way loudspeakers such as Vivid's Oval V1.5, which I wrote about in my October 2010 column. The V1.5 similarly lacks audible distortion but also sounds more transparent, with greater resolution of fine detail. At $7600/pair—five times the price of the ATC—it should.

The ATC SMC7 v.3 is an extremely competitive entry in the British Shoebox Monitor sweepstakes. That it's made in the UK by a company known for making professional monitors, and has first-class fit'n'finish and addictively engaging musicality, are strong arguments in its favor. I didn't have on hand a pair of KEF LS50s with which to compare the SCM7s. However, from what I recall of the sound of Harbeth's P3ESR—over which I exclaimed "Gloriosky!" in October 2005—the SCM7 v.3 was as listenable and enjoyable. While the Harbeth retains a bit of the LS3/5A's midrange sweetness, the updated SCM7 seems designed to be a thoroughly modern mini monitor. And the ATC costs $700 less per pair.

Well done, indeed, and highly recommended. I look forward to the arrival of ATC's SCM19.

Plangent Processes offered me a review set of their high-resolution downloads of all the studio albums by the Grateful Dead, later chosen as the December 2013 "Recording of the Month." I downloaded both 24-bit/192kHz Apple Lossless and 24/96 FLAC versions. Played via Amarra, they sound stunning.

The Dead were one of my youthful musical enthusiasms, once I heard their two-LP set, Live/Dead, sometime in 1970. I then applauded their move into folk/Americana territory with Workingman's Dead. I heard them in concert—including, apparently, their last gig before they finished putting together all the pieces of their legendary PA system, the Wall of Sound.

The Dead were unusual for their time in paying, from 1966 on, great attention to their live sound and, later, to their studio sound; for example, they're reported to have taken the tape-recorder live feed before the PA mixing desk rather than after, by means of a custom-designed splitter (today we would probably call it a distribution amplifier). And at a time when lots of good music was being recorded in sound that ranged from so-so to just plain awful, from overuse of every effects box in the studio (listen to Quicksilver Messenger Service's studio album Fresh Air), the Dead's records, especially their studio albums, sounded, in comparison, pristine.

Even so, I was unprepared for the sonic revelation of these remasterings of the Dead's studio albums. The cliché of "a cleaned window" actually describes what I heard. Wanting to learn more, I spent more than an hour on the phone with Jamie Howarth, a principal of Plangent Processes.

Plangent is neither a hardware maker nor a software firm. The Plangent process requires not only proprietary hardware and software; it also requires esoteric expertise, and the intervention of human judgment at the critical stage of recovering the bias tone of the original analog master tape. What follows is a huge oversimplification, but . . .

The AC bias tone used by an analog tape recorder is an inaudible, steady-state, ultrasonic signal that's added to the sound being recorded. The bias tone reduces noise and distortion in part by eliminating the effect of the tape material's magnetic hysteresis.

If one wanted to set out a Grail Quest Problem in the engineering of analog tape recordings, the task of recovering a residual tone that's somewhere between 100 and 400kHz, and at a level lower than –90dB, surely takes the cake.

Plangent accomplishes this via a three-step process. The original master tape is played on a modified tape deck with a custom head stack and electronics, both with bandwidth to 500kHz, then converted to a digital signal at 192kHz. The hard drive containing those digital files is sent to Plangent's laboratory on Nantucket Island. The data are upconverted and the search for the ghost of the bias tone begins.

Once the bias tone is identified, its frequency fluctuations are mapped. Because the bias signal is assumed to be a steady tone at xkHz, any deviations in its frequency—ie, the tone's Frequency Modulation Distortion—must be the result of mechanical deviations in the tape's speed—wow and flutter—which consequently alter the pitch of the notes being played.

In reality, it's even more complicated. A fast flutter above 30Hz manifests itself as intermodulation distortion. Some tape transports also exhibit scrape flutter, wherein the tape head acts like a violin bow, the tape "singing" at a frequency proportional to its unsupported transport length and its tension, as does a violin string. None of this process takes place in real time; rendering one song can take an entire day.

To put it another way, Plangent's "Eureka!" moment was to use the ghost of the analog tape bias tone as a timing reference to enable their engineers to correct for mechanical and tape-transport problems not only in the playback deck recently used for the digital transfer, but also in the deck used in the original recording. Simply amazing. So Plangent removes two layers of grime, and, to the greatest extent possible, removes only grime, and not music—and, just as important, without adding any new artifacts. In our chats, Howarth more than once invoked Hippocrates' injunction "to do no harm."

Howarth also shared his fascinating perspective on why Ivor Tiefenbrun's original Linn Sondek turntable was thought by many audiophiles to sound more musical in comparison to the direct-drive, speed-correcting turntables of the 1970s. The Sondek was so heavily damped and its platter so heavy that it didn't introduce new chatter or jitter of its own, as did the constant speed corrections and resulting intermodulation distortions of the typical Japanese hi-tech turntables.

To demonstrate what Plangent Processes can do, the Web reprint of this column includes brief excerpts from the soundtrack of the film East of Sudan (1964).

First is the flat transfer, showing gross speed fluctuations.

Second, some progress (but also with audible processing artifacts) from software-only processing using a popular digital editing program or DAW.

Third, Plangent Processes' version.

The music, which sounds to me like Alex North of the other 2001 score, is by Laurie Johnson, who has his own Kubrick connection—he composed the music for Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb.



c1ferrari's picture

Hi John,

Thanks for the article.  Would you know if this tweeter will be retro-fittable to the Classic Series active 50's, 100's, or 150's?  If so, would it entail revision of the electronics, i.e., amps and/or crossover, to optimize for the different driver?



ATC Loudspeakers's picture

Dear Sam,

There will be retro fittable tweeter upgrade kits available for classic and tower SCM20/50/100/150 loudspeakers.

Ideally, following the change of any drive unit component (link-for-like or a different component), the response of the loudspeaker should be tested.  However, tests so far have shown that the new tweeter can be fitted with no crossover modifications and an excellent response achieved, within the +/-2dB amplitude linearity specified.

Kind Regards,

Ben Lilly

ATC Loudspeaker Technology Ltd

ATC Loudspeakers's picture

I should also add that there will be two versions of the new ATC tweeter.

1.  The SH25-76 as fitted to the Hi-Fi Passive Series (SCM7/11/19/40).  This is the standard version of the new tweeter.  This will not be available as an upgrade part for older models.

2.  The SH25-76S.  This has not yet been launched and will be the part fitted to our higher performance and/or larger more efficient models (SCM20/50/100/150).  This is the 'Super' spec part and has higher efficiency and an extended high frequency response by use of a more powerful (2.0 Tesla) motor assembly.

Kind Regards,

Ben Lilly

ATC Loudspeaker Technology Ltd

edbudzil's picture

Hi, John,
Thanks for the informative article. At AXPONA in Chicago this spring, one of the best speakers I heard was a company's first speaker, the Benchmark SMS1 Loudspeaker. Turns out this is a sealed box, you can read their design perspectives on the Benchmark webpage. Hope you'll get to hear it and maybe review it. Getting a bit off-topic here, one comment regarding the show, I think manufacturers with a broad product line are missing a huge opportunity by only showcasing their statement products (often at ridiculous volume levels). At least they should have a second "real world" room, and show potential buyers just how good complete systems in the under $5,000 range have become.