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ATC SCM50 ASLT Loudspeaker

ATC SCM50 ASLT Loudspeaker

Audiophiles and active loudspeakers have had, shall we say, an uneasy relationship over the years. The squabble goes something like this: Active speakers (defined here as speakers equipped with on-board amplifiers and electronic crossovers) are the outsiders, creations of and for the recording studio—only pros need apply. The argument continues that while active designs tout tonal accuracy, they are just as often described as amusical and clinical-sounding beasts geared to play all day and night at ear-splitting levels.

Some of these generalizations contain seeds of truth, but many are mere clichés from a bygone era. Really, the only serious gripe that is still valid is that the “active” approach is antithetical to the audiophile norm—a culture of discrete-component system-building, with the freedom to choose any product in the electronics chain and not be wedded to it for life.

However, time, tastes, and technology have narrowed, if not mended, the great divide between the passive and active camps. Today, for example, there are countless hybrid models with powered bass transducers (Vandersteen, MartinLogan, GoldenEar). Wireless and DSP have also opened up fully active options for designers (Linn, Dali, Elac, KEF, Dynaudio). And I don’t need to remind anyone about the popularity of powered/DSP subwoofers, right? Suddenly plugging a loudspeaker into a wall outlet doesn’t seem like such an act of heresy.

One certainly doesn’t need to convince ATC of England of this. The company has been in this game since its founding in 1974. Acoustic Transducer Company (ATC for short) actually began by concentrating its efforts on the design and in-house manufacture of custom transducers for the pro-sound market. By the end of that decade it had started producing professional active monitors, adding electronics and amp packs soon thereafter, and then, finally, consumer-oriented products.

The SCM50 ASLT (active super linear tower) reviewed here has a particularly long and distinguished lineage within ATC, one that dates back to the mid-1980s. The original SCM50A came into being as the result of a request by Danish Radio for a compact monitor speaker for its broadcast trucks. Subsequently adopted by recording studios, it has steadily evolved with the passage of time. I’ve encountered ATC in recording studios as recently as a few years ago when I visited the late Doug Sax at The Mastering Lab.

The SCM50 ASLT is a three-way floorstander that tops out at around 40″ in height and a foot in width, and thanks to its amp-packs extends rearward a full 18″. For ATC-watchers, this model is the tower version of the famed SCM50 ASL Pro Monitor, which still graces many a studio today. The look is that of a traditional British loudspeaker—boxy, understated, yet handsomely brutish. The midrange and tweeter drivers are vertically offset relative to the woofer, reducing the effects of cabinet diffraction and permitting the user to orient the speaker according to taste—drivers inboard tend to pinpoint images and add depth to the musical stage, while outboard adds a bit more width. As described by Ben Lilly, Engineering Applications/Sales Manager, “The cabinet is braced and damped with 18mm MDF. Damping panels are a multi-layer bitumen-type product glued and stapled to the cabinet’s inner face. The baffle is 25mm thick. We use a thicker, heavier, more inert front baffle on many of our products because this panel faces the listener—panel resonances from this area are more audible.” There’s no scrimping on cabinet fasteners, either. The baffle is secured with fourteen Allen-type bolts, the woofer alone uses eight more. Should you wish to disguise these details, the grille frame is cleverly designed to snuggle around the edges of the projecting front baffle for low diffraction. Standard finishes include satin cherry, oak, walnut, and black ash. I found the overall fit and finish excellent—it speaks to solidity and permanence.

This is a tri-amplified loudspeaker that delivers 200W to the woofer, 100W to the midrange, and 50W to the tweeter. The Class AB MOSFET amplifiers mounted on the rear panel are augmented with a bank of heat sinks and large grab handles. The SCM50 accepts only balanced XLR inputs and the included power cords are detachable. In operation, the amps are dead silent.

The heart of every loudspeaker is its transducers. To ensure that heart is beating, ATC doesn’t leave its designs to third-party manufacturers. Each driver is a bespoke ATC unit, engineered and manufactured in its venerable factory in Stroud, England. Most recently, and after many years of development, ATC introduced its own 1″ soft-dome tweeter, model SH25-76S S. It’s a non-ferrofluid, double-suspension design in a shallow waveguide. The 9″ woofer is one of ATC’s top-drawer Super Linear models, purposefully engineered to reduce eddy currents and lower harmonic distortion. Easily the jewel in the crown of ATC transducers is the 75mm soft-dome midrange, model SM75-150S. Developed in the 1980s, it’s a dual-suspension design for better diaphragm control, greater heat dissipation, and higher power handling. Equipped with a huge three-inch voice coil, it’s renowned for its power handling and lack of compression. Per ATC practice it uses a short coil operating in a long magnetic gap (aka, it is underhung). This particular model is the pro “S” or super-version, which offers a larger magnet for increased sensitivity (92dB/1W/1m), extended upper-mid response, and lower distortion. To further extend response it is mounted in a “phase correction flange.” Like every driver in the ATC family, it is a massively built transducer that tips the scales at nearly twenty pounds—yes, you read that correctly. For one driver. The crossover is a fourth-order Linkwitz-Riley type, with hinge points at 380Hz and 3.5kHz.

Admittedly I felt an instant familiarity with these speakers. Truth be told, I’ve owned ATC passive two-ways like the SCM20SL for years. Also, I recently reviewed the excellent    SCM19A, an active two-way floorstander. Sonically, there is a signature design philosophy that ATC and its founder Billy Woodman have hewed to since the firm’s inception. It begins with the “instrument of the orchestra,” the piano. For a product to reproduce a piano’s full range of expressiveness and sustain, of harmonic authenticity and dynamic explosiveness, it must be capable of a very high level of musical truth. A pianist himself, Woodman (and his team) use the sound of a piano to weigh every ATC design.

The SCM50’s character is underscored by three key properties: One, midrange presence and immediacy; two, midband speed that borders on electrostatic territory; and three, a staggeringly wide dynamic envelope that easily puts electrostats and most cone loudspeakers of this size and spec to shame. In tonal balance, the SCM50 is an exemplar of ease and neutrality across the octaves. This is a no-nonsense speaker, not subject to hyperbole in any frequency range. Its drivers integrate smoothly, speaking with a single authoritative voice, each driver in step with the other. The soft-dome tweeter, especially, deserves kudos for its ease, extension, and openness—a profound improvement over the drier, whiter, third-party tweeters that ATC had to outsource in years past. Transient behavior is smooth rather than underlined and exposed for effect. Bass response plummets effortlessly and aggressively into the mid-thirty-cycle range in my room. Some might opt for more extension but few will be disappointed with the quality that this response represents. Low-frequency musicality is stunning—a combination of pitch control and effortless slam that are hallmarks of ATC’s active products. The SCM50’s woofer has an enviable ability to resolve textures and timbral colors, capably rendering the skins of bass drums, or the flutter of tom-toms, or the dark voicing of orchestral bass viols as bows are dragged across their strings. Where the SCM50 really grabs attention is its talent at holding onto the decay of bass notes. Many speakers are uneven in response or subject to dropouts in the upper-bass and midbass regions. Music reproduction suffers amplitude ups and downs, depending on the pitch of the note and the involvement of the port. Just listen to the acoustic bass in either Harry Connick, Jr.’s cover of the classic “A Nightingale Sang in Berkeley Square” or Dave Brubeck’s “Take Five.” In both instances, the ATC treats each change in pitch with timbral and textural consistency—and does so with an output that doesn’t rise then precipitously fall off. If you really want to hear Paul McCartney’s bravura chops on electric bass guitar listen to “Dear Prudence” aboard the SCM50. The sheer musicality and weight of Paul’s bass playing is fully captured by the level of linearity and midbass dynamics that this speaker produces.

The midrange, with its extended frequency bandwidth, provides the thrills and dynamic thrust that I’ve come to expect from this potent 75mm dome. As I listened to the Manhattan Jazz Quintet playing “Autumn Leaves,” I found images leaping from the speaker like a cat pouncing on a meal. When the trumpet solo kicked in, it was as if the SCM50 had been hiding a can or two of propellant inside its enclosure, just for igniting dynamics.

The SCM50 has an almost eerie immediacy that seems to glean the intent of the musician before his bow touches the string or a note escapes his lips. And piano reproduction is, in a word, breathtaking with an extended range of soundboard weight and resolution that reaches all the way back to the touch of the player’s fingertips.

It would be easy to peg the midrange dome as the only hero of this story, but it’s equally about the inter-driver transfer of the signal—just how well the tweeter and woofer gel playing above and below the midrange. If all the drivers were not equally up to the task, then the transparency of the midrange dome would be unrealized.

Parenthetically, I also had to rethink the issue of dynamic compression on some of my treasured recordings. Turns out it wasn’t always the recording to blame. With the SCM50, keep in touch with your preamp’s volume knob; one of those vinyl albums may shock you with what’s been heretofore hidden in the grooves.

Vocals are fluent, at times almost voluptuous, in their weight and harmonic bloom. Diana Krall’s “I’m Confessing’ That I Love You” is ripe with inflections and a smoky sensuality that wraps itself around your ears. Inner dynamics—the way a singer uses the microphone to capture the intimacy and emotion of a song, moving in towards the mike or farther away to massage micro-dynamics—are equally well expressed. After listening to Mary Travers during PP&M’s “All My Trials,” on an Audio Fidelity SACD, I had to sit back and ponder the eerie reality of what I’d just heard from this fifty-year old minimalist recording. The fly-on-the-wall, “you are there” moments that this track offered were nothing short of a time-machine trip.

The SCM50 thrives, even gathers energy when challenged to reproduce orchestral music. Rather than constrict, lose air, or reduce inner detail as the strings and winds rise in a flurry of complexity, the ATC seems to sail through with aplomb. Similarly, its resolution doesn’t falter as it tracks the sustain and decay of instruments, whether it is a crash cymbal, an organ, or a cello. But what really took my breath away are the layering of images and the width of soundstage reproduction. Less desirous is a lack of vertical soundstaging. The midrange has a specific and direct sound energy. Consistent with its studio roots, the speaker pinpoints images in depth and width. This is a virtue, but there is also a sense of a ceiling over the acoustics of a concert hall that may take an adjustment for some listeners.

In order to discover for myself the sonic distinctions between active and passive, ATC, through its U.S. distributor Lone Mountain Audio, dispatched to me a “conversion kit,” so I could swap out the amp pack/electronic crossover for the standard SCM50 passive crossover, thus creating a near-identical version of ATC’s SCM50 PSLT (P for passive, $21,999). ATC also kindly provided me with its P2 stereo amplifier for the comparo. I managed to make the switch without incident. Minus the tri-amplifying amp pack, this was not truly an apples-to-apples comparo but it was instructive. The differences were obvious. The speaker’s tonal character didn’t change, but its presentation was a tad less self-assured. Images didn’t quite adhere to spatial positioning like they were stuck on flypaper. Soundstaging was just a tad amorphous. The upshot? Still a brilliant speaker, but I’ll take mine with an AC plug, please.

Normally, when I’ve concluded my time with a review product I’m of a somewhat mixed mind, weighing attributes and oddities, balancing the great against the not-so-great. In the matter of the ATC, its exemplary performance over so many criteria pushed any lingering issues into near-insignificance. I think you see where this is going. Yes, I bought these speakers—my review samples being a well-travelled demo pair that had seen life on the road for the better part of two years. They’ve now found a permanent home and will not only be valuable tools going forward, but splendid musical companions in the years to come. Is active for everyone? I’m sure it’s not. But for enthusiasts who are willing to open their minds just a bit, ATC might be the first call you should make.

Specs & Pricing

Driver complement: HF 25mm ATC SH25-76S, mid 75mm ATC Super Dome, LF 243mm Super Linear
Frequency response: 38Hz–25kHz
Power output: 200W LF, 100W mid, 50W HF (active version)
Max SPL: 112dB
Dimensions: 12″ x  40.2″ x 18.9″
Weight: 117.5 lbs.
Price: $28,999 (satin cherry, oak, walnut, black ash)

ATC LOUDSPEAKER TECHNOLOGY LTD.
Gypsy Lane
Aston Down
Stroud, Gloucestershire
GL6 8HR, England
atcloudspeakers.co.uk

ATC HIFI USA (U.S. Distributor)
(702) 307-2727
lonemountainaudio.com

Neil Gader

By Neil Gader

My love of music largely predates my enthusiasm for audio. I grew up Los Angeles in a house where music was constantly playing on the stereo (Altecs, if you’re interested). It ranged from my mom listening to hit Broadway musicals to my sister’s early Bob Dylan, Joan Baez, Beatles, and Stones LPs, and dad’s constant companions, Frank Sinatra and Tony Bennett. With the British Invasion, I immediately picked up a guitar and took piano lessons and have been playing ever since. Following graduation from UCLA I became a writing member of the Lehman Engel’s BMI Musical Theater Workshops in New York–working in advertising to pay the bills. I’ve co-written bunches of songs, some published, some recorded. In 1995 I co-produced an award-winning short fiction movie that did well on the international film-festival circuit. I was introduced to Harry Pearson in the early 70s by a mutual friend. At that time Harry was still working full-time for Long Island’s Newsday even as he was writing Issue 1 of TAS during his off hours. We struck up a decades-long friendship that ultimately turned into a writing gig that has proved both stimulating and rewarding. In terms of music reproduction, I find myself listening more than ever for the “little” things. Low-level resolving power, dynamic gradients, shadings, timbral color and contrasts. Listening to a lot of vocals and solo piano has always helped me recalibrate and nail down what I’m hearing. Tonal neutrality and presence are important to me but small deviations are not disqualifying. But I am quite sensitive to treble over-reach, and find dry, hyper-detailed systems intriguing but inauthentic compared with the concert-going experience. For me, true musicality conveys the cozy warmth of a room with a fireplace not the icy cold of an igloo. Currently I split my time between Santa Fe, New Mexico and Studio City, California with my wife Judi Dickerson, an acting, voice, and dialect coach, along with border collies Ivy and Alfie.

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