ATC SIA2-100 Amplifier / SCM7 Loudspeaker System Review

Posted on 25th March, 2020

ATC SIA2-100 Amplifier / SCM7 Loudspeaker System Review

Jay Garrett auditions a small system from Great Britain with a serious sound…



£2,500 / £875 respectively

The Acoustic Transducer Company has been designing loudspeaker drivers since 1974 when founder Billy Woodman started manufacturing custom units with the debut of the 12-inch PA75-314. A soft-domed midrange driver landed in 1976, and ATC's first speaker systems followed a decade later, with Pink Floyd and Supertramp being notable early adopters. Then in 1996, the company announced its first electronics, thus making ATC a one-stop-shop.

This potted history lesson also underlines the fact that ATC could be seen as the middle child, coming into the world between venerable Brit brands Spendor (1969) and Harbeth (1977). Where these two have since cemented their names in the domestic arena, ATC has concentrated more on professional audio. Having attempted a career in music performance, I have enjoyed many an ATC-monitored studio – most recently Mark Knopfler's British Grove operation, as a member of the press and not a muso, I must add. It is perhaps understandable then that owners of ATC loudspeakers include T Bone Burnett, Enya, Diana Krall, Lenny Kravitz, Ziggy Marley, Paul Reed Smith, Sting and Roger Waters, to name but a few…


ATC SIA2-100 review

Although not particularly well known for its electronics, the company has a good reputation all the same – with an accent on ruggedness and reliability. The £2,500 SIA-2100 is a compact integrated amplifier, claimed to put out 100W RMS per channel into 8 ohms. It's an oddly sized package, measuring a somewhat idiosyncratic 113x315x315mm (HxWxD); this puts it neither in the half- nor full-sized camps. 

ATC SIA2-100 review

This form factor combines with the asymmetrical fascia to give a quirky but not unattractive look. Its front panel sports a standby button, a smooth-turning volume control, 3.5mm stereo input port, letterbox display and 6.3mm headphone socket that sits at the end of its own amp and discrete output stage. Before we flip the unit around, let us pause for a moment to gaze upon the amplifier's arced airflow vents. I love it when designers add touches such as this. Yes, they could've had a pair of parallel grids which would have been easier and cheaper to tool, but no. This was their vision, and it stayed.

ATC SIA2-100 review

Inside is an AKM 32-bit DAC for digital sources, which is a somewhat leftfield choice and – if I may say – a good one. It supports sampling rates up to 24-bit/192kHz via the coaxial digital input, while USB does 32/384 and DSD256 with a Windows machine running the latest driver. Mac OS X users don't need to download a driver, but their output is limited to DSD128, according to the company. In addition to this, there are two sets of analogue line inputs, banana-friendly speaker terminals and a set of analogue line outs. 


ATC SCM7 review

ATC continues to offer both professional and consumer lines of loudspeakers, the latter kicking off with the entry-level £875 SCM7 passive standmounter you see here. The number refers to its cabinet volume in litres, so it's understandably compact at 300x174x215mm (HxWxD) – and feels about as solid as anything of this size can be. Its laminated, curved-sided cabinets look stylish no matter whether you choose cherry or black ash veneer, satin black or white. The woodwork, we're told, is of a heavily braced construction for rigidity and damping. 

ATC SCM7 review

Its two drive units are flush-mounted to the SCM7's baffle with the 25mm soft-dome tweeter sporting an alloy waveguide to control dispersion. The 125mm mid/bass unit has an integrated version of the company's famous soft mid-range dome. Both drivers are of ATC's own design, of course, with the tweeter build and flat wire coil winding taken care of in-house. Additionally, the larger driver has a substantial optimised motor assembly, says the company. This, along with all that internal bracing, means this pocket-rocket tips the scales at a hefty 7.5kg.

Completing this loudspeaker's aesthetic is the all-metal, hex-mesh grille which, on our black ash review pair, is an attractively contrasting grey. It attaches via concealed magnets and oddly – in this reviewer's opinion – looks better on than off. On the rear panel are two pairs of non-insulated binding posts for bi-wiring, with jumpers already fitted for those of us using a single pair of speaker cables.

ATC SCM7 review

ATC states that the SCM7's frequency response is 60Hz–22kHz at -6dB points. Being an infinite baffle design, and a small one at that, it doesn't come as a complete surprise to see a low quoted 84dB/W/m sensitivity, albeit with an 8 ohm nominal impedance. The manufacturer says that this loudspeaker presents a flat impedance curve, which is an easy load for amplifiers putting out between 75 and 300W per channel. Note then that you'll need a muscular solid-state amp to drive it, so 3W parallel single-ended tube designs need not apply!

A compact system that punches way above its size, it sports incredible presence given its small stature…


I first plugged the ATC SCM7s into my reference Naim Nait XS3 integrated amplifier to get a feel for them, and immediately heard that classic British small speaker sound. It's not about seismic bass and a clinical, precise midband. Rather, rhythmic agility and tonal purity count here – and the little ATC has these in spades.

ATC ACM7 review

Listening to the panned samples and neatly separated instrumentation of the Propellerheads' Her Majesty's Secret Service, and it was easy to see how one could quickly get addicted to this dinky diamond. The guitar work was marvellously sharp and vital, with the horns cutting through in a vibrant and visceral way. Further down the scale, and the bass sounded practically indestructible. Feed this little loudspeaker with Aura by Belfast-raised DJ duo Bicep, and you'll soon have the woofer dancing in and out athletically, showing its impressive excursion.

Due to its infinite baffle design and small cabinet volume, the SCM7 cannot match larger loudspeakers in terms of punching power, but it's still a thrilling listen. Massive Attack's Angel maintained its underlying menace thanks to the grumbling sub-bass work, without losing any clarity further up. So, when the bottom-end is being tested, the rest of the mix doesn't play second fiddle.

ATC SIA2-100 review

Next, I hooked up ATC's own SIA2-100 integrated amplifier to the SCM7s, with interesting results. I heard more immediacy in the midband – the already impressive imaging was even more dialled in and focused. Indeed, the amount of goosebump-inducing detail was immediately noticeable as the opening acoustic chords of Joni Mitchell's Sisotowbell Lane filled the room. The guitar had a warm resonance and lifelike clarity, while Joni's high range vocals stayed sweet and bright without ever fatiguing the listener.

Similarly, the crisp leading edge of the piano introduction to Wuthering Heights was rendered clear as crystal before Kate Bush's unmistakable voice cut through the still. The upper register was tamed by the weight of the pianist's left hand, which was joined by the warmth of producer Andrew Powell's fretless bass work. This ATC system's sophisticated tonal balance made for an even presentation of what – on some hi-fi systems – can be a teeth-grinding experience if left to the vagaries of lesser kit. No such fear here, however!

ATC SIA2-100 review

For yours truly then, the standout feature of this system is its excellent handling of both the time and frequency domains. By this I mean it is rhythmically fast yet tonally smooth. For example, the staccato instrumentation of Human League's Don't You Want Me hit me like a series of metronomic walls thanks to Martin Rushent's production mastery and the track's chart-friendly beat. At the same time, there was a believable tonality that didn't grate or tire. Factor in the fine soundstaging – where every aspect of the multi-layered mix was placed in space perfectly – and you have a serious-sounding system.


ATC Applause AwardThe ATC SIA2-100 amplifier and SCM7 loudspeaker combination is a compact system that punches way above its weight – indeed it has incredible presence given its small stature. This dinky duo is tonally balanced, rhythmically articulate and has precise stereo imaging too. Even driven heavy-handedly with juicy bottom-laden dance grooves, you'll be hard-put to hear any complaints from the ultra-capable drive units. Instead, you will be treated to textured low-frequencies delivered with conviction and realism, a midband of clarity and focus, and smooth yet mustard-keen tweeter. Overall then, whether you choose this system because of its size, build-quality, performance, and/or country of origin, you'll not regret auditioning it one bit. Catch it if you can.


      Jay Garrett's avatar

      Jay Garrett

      StereoNET UK’s Editor, bass player, and resident rock star! Jay’s passion for gadgets and Hi-Fi is second only to being a touring musician.

      Posted in:Hi-Fi Amplifiers Integrated Amplifiers Loudspeakers Bookshelf / Standmount Applause Awards 2020
      Tags: atc 


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