1 Review by James L. Darby ATC SCM 50ASLT Classic Tower ( Active ) in Black Ash - $20,900 With Cherry Finish as tested - $21,600.00 If you are not familiar with the ATC brand of speakers, you are probably not involved in the recording industry. ATC speakers and electronics are as common in recording, mixing and mastering studios as rainy days in Seattle. According to their website, artist 2 who use ATC speakers include Pink Floyd, Mark Knopfler, Tom Petty, the Rolling Stones to name just a few. The people who make those artists sound good are the engineers and the list there is even more impressive with names like Doug Sax, George Massenburg and Bob Ludwig among them. Sony uses ATC’s in their New York SACD studios. So does Abbey Road, Warner Brothers, Polygram and Naxos among many others. One name listed jumped out at me as a guy I had exchanged several emails with over the years. He recently won his seventh Grammy for engineering on the Telarc label. His name is Michael Bishop. So, I dropped him a line and asked if he and Telarc did indeed use ATC monitors. His answer was an enthusiastic “Yes! I use the ATC SCM- 50s quite frequently at Telarc, in studios and at home. I’m a big fan of ATC’s speakers in general. My associate, Rob Friedrich, also uses the ATC’s almost exclusively in his sessions. We have ATC’s in every post-production room and on every Telarc session”. In addition, from ATC's website is this quote: Whether at home in Cleveland or on the road, he relies on five ATC 150 midfield monitors. The highest of the high-end speakers, ATC 150s are often found in mastering studios. However, Bishop reasons that the qualities that make them ideal in a mastering studio also make them ideal in critical direct recording. 3 "The extreme resolution of the ATC 150s reveals the slightest shift in mic position or the subtle effects of changing atmospheric conditions," he explained. "At the same time, they're very musical and fun to listen to, even after long hours of tracking." Since a single ATC 150 weighs nearly 200 pounds, the fact that all five travel with him says something about their indispensability. "Stage crews are seldom happy to see us pack in with half a ton of speakers," he laughed, "but that's what I need to have to do my job properly." ATC (Acoustic Transducer Company) was founded in Britain by Australian born Billy Woodman in 1974. In an exclusive interview with him, he said that the company’s first big break was supplying the midrange driver for Super Tramp’s live touring rig in that first year. Billy studied electrical engineering in Victoria, writing his final paper on loudspeaker design. “Many of the best American jazz players gave concerts in Melbourne and it was listening to live jazz that fired my interest in loudspeaker design and high resolution audio reproduction. It is my love of music and finding the most effective engineering solutions to solve problems that drives me and keeps me enthusiastic and motivated. I am a fortunate man to have been able to work and make a living doing what I most enjoy in an industry that I love”, he told me. When I asked specifically about the design goals of the ATC 150, he replied, “We set out to design a product for the domestic market that was the sum of our experience and knowledge and which employed the most effective of modern engineering principles whilst being packaged to appeal to the audiophile as well as the music lover. The SCM50ASL is set apart from the competition because of its huge dynamic range, excellent linearity, corrected 4 phase response, very low non-linear distortion, well controlled time domain anomalies and broad and even dispersion verses frequency. In fact, when I set out to design the (smaller) SCM50 originally the aim was a turnkey loudspeaker of exceptional performance and dynamic range in a relatively small package. Most of this is also true for the tower. It is the performance of the midrange dome, the SL bass drivers and their integration through the purpose designed Ampack (built in amplifiers) that makes this product hard to beat. ATC still makes, I think, the most highly specified drive units in the world and that does differentiate us in the market”. If you did not catch it, it should be reiterated that ATC designs and makes all of their own drivers in house. As you know, most speaker makers take drivers made by other companies and design enclosures and crossovers around them. But ATC does not stop there; they also design and make their own amplifiers to drive them. Studio monitors are all about precision and Billy found early on that the only way to have total control over quality and precision was to do it themselves. The ATC SCM50SL is a three-way, self powered tower that is a little over 3’ tall, a foot wide and 18 ½” deep. Each speaker weighs a hefty 188 lbs. While the tweeter is a 25mm Neodynium soft dome, rather uniquely and of special note, the midrange is also a soft dome design; a concept developed by ATC. The woofer sizes up as about 91/2 inches. Each of these drivers has its own amplifier custom designed to match its characteristics. The top end is powered by 50 watts, the mid 100 watts and the woofer has its own amp rated at 250 watts for a total amplifier output of 400 watts per cabinet. There are several qualities that are absolutely essential for a speaker in a commercial recording studio environment. First, it has to accurate with a frequency response that is as flat as possible. The engineer has to be able to hear exactly what each instrument and vocalist sounds like with no coloration, dips or peaks. Distortion is the bane of every recording session that can and often does last 5 for 18 hours a day. Distortion causes ear fatigue and with precious, costly studio time and very tight deadlines, engineers cannot afford to have their ears and minds going south after a couple of hours. Speakers have to be built like tanks to be bulletproof. Accidents always happen like when a mic feed from the studio is left open too wide and sound comes through that would instantly trash the typical home speaker. Or that loopy guitar player who turns up his Strat without telling the booth. Check out the construction of the ATC's woofer at left. Notice the extreme number of fasteners and how close they are to each other?Check out your woffers and see how fastidiously they are mounted. This reminds of 12 bolt main on a dragster. They have to be extremely fast to deal the transients only live music can generate. And, of course, they have to be detailed. Recording sessions are all about details when you are working with effects that are measured in microseconds and a couple of microseconds too much or too little can make the difference between a recording that is too dense or spars, muddy or clean. If you were having brain surgery, you wouldn’t want your surgeon using tools he picked up at Home Depot. It’s the same with recording engineers; their tools have to be precise, perfectly balanced and antiseptically clean. As mentioned above, a very unique feature of the ATC SCM50SL’s is the large, soft-domed mid-range driver. I asked designer Billy Woodman about it; “The idea for the soft dome goes back to my days as a young engineer and student trying to find a solution to the problem of combining high 6 performance and large dynamic range. At the time, Britain was well known for producing loudspeakers of excellent acoustic performance but with limited dynamic range (Quad ESL63, Rogers LS3-5A etc.) and the US for loudspeakers that would play very loud but at the expense of acoustic performance. The ATC soft dome midrange covers a full decade of frequency, 350Hz to 3500Hz typically +/- 1.5dB, the most critical range of the human ear, and does so whilst generating very low harmonic distortion (-45dB second harmonic and -63dB third harmonic). It has a sensitivity of 1W@96dB@1M due to its light structure and high flux density magnet and is the only transducer I have encountered where the mass of the drive system equals the mass of the diaphragm assembly thus ensuring maximum power transfer. The voice coil is 75mm diameter and under-hung (3.5mm long coil in a 5.0mm magnet gap) to minimize distortion and maximize power handling capacity. The voice coil also has a double suspension to minimize diaphragm wobble modes, which cause unwanted distortion. The magnetic circuit is made of annealed pure iron to optimize flux density in the magnet gap. The dome is only 75mm diameter which guarantees broad and even dispersion verses frequency over its operating range. The dome itself is made from a fabric that is formed and onto which is applied a viscous damping medium optimized to deal with any structural resonance and time domain anomaly”. Being self powered, the ATC’s employ built in amplification called the “Ampack” previously mentioned. Woodman told me that the Ampack incorporates phase correction and momentary gain reduction to prevent clipping the amplifiers when listening to very loud music when the output stage is driven to near full output. Bulletproof. The power stage of the amplifier is of a ground source MOS FET design and operates in class AB.