Hardware Reviews



When Prism Sound launched their first consumer product the Callia DAC they chose Mark Knopfler’s British Grove studios to do it in. The venue has more than its fair share of ATC monitors (they have the big ones of course) but the character of all ATC speakers is much the same, warts-and-all detail resolution of the neutral flavour. Many speaker manufacturers profess to designing high resolution, low colouration products with as flat and neutral a response as they can manage – although thus far it has not been possible to produce a totally even response from an acoustic transducer. But there are a lot of tuning decisions made during the voicing stage of a loudspeaker and this is where character usually creeps in. At ATC they seem to avoid this and as a result their loudspeakers can be sometimes be less than flattering. I have found myself thinking why does this sound so dull before making a change to the source or amplification and discovering that I was hearing limitations further back in the chain. This much was apparent at British Grove where some of the music they played sounded incredibly real and vibrant, with wide bandwidth and superb dynamics, whereas other material was quite the opposite, heavily compressed and surprisingly bright in one case. This was mostly music that had been commercially released and in some instances proved extremely successful, all the ATCs were doing was letting you hear what was on the recording.

All speakers are at the mercy of their ancillaries but many manage to smooth over shortcomings by providing a bit of sparkle in the upper mid or some selective boosting of bass frequencies. And of course by blurring detail at other frequencies; not many are transparent across the band and many produce nearly as much colour as actual signal. Music is a forgiving medium, you don’t have to hear everything perfectly in order to enjoy it, otherwise the sound in cars for instance would be intolerable, and Bluetooth speakers, don’t get me started!


ATC SH25 76S tweeter



I don’t get the impression that ATC goes in for flattery in sound, it goes against the company’s pro audio ethos, their speakers are ultimately made for people who want to hear the good and the bad in a recording so that they can do something about it one way or the other. The SCM19A is ATC’s latest model and the least expensive active floorstander in the range. It stands just under a meter high without spikes and carries a 182 Watt power pack on its back. This breaks down to 150 watts for the six inch mid/bass driver and 32 Watts for the 25mm soft dome tweeter, both drive units are made in house and the bigger unit is an SL or super linear type with a large, integral soft dome in its centre and a massive motor system behind. The crossover is an active electronic type and connection is made via an XLR socket in the amplifier.

To cater for EU regs there is a cross brace that bolts to the base and extends the footprint out to enhance stability, although the high mass and relatively compact nature make it quite a hard speaker to topple without this. The on/off switch is next to the mains inlet on the back but there is no indication as to its status, suffice to say that when it’s on you can play music, which is nice! The styling is typically bluff, real wood veneer or matt black or white, Trevor Butler of this parish found the cherry pair I tried a little bit imposing, but he’s not a fan of veneer finishes it seems. There is no port on the SCM19A because it’s a sealed box, which is the case with a lot of ATCs, it’s an approach that reduces sensitivity but generally confers lower bass distortion, and when you have active drive sensitivity isn’t really an issue.

And the active drive is a fundamental part of this speaker’s appeal, it confers and ease of power that is very hard to achieve with passive speakers. By taking the crossover out from between amplifier and drive unit you instantly make the amplifier’s life easier, giving it a far better chance of controlling the voice coil and thus reducing distortion. An advantage that is more obvious at higher levels where control becomes more of an issue in conventional systems. The SCM19A therefore sounds like it has huge headroom, that no dynamic peaks will be restricted and that you can play at high volumes without the distortion that makes the experience uncomfortable. But it’s not all about power, it’s also about articulation, this speaker can reveal an awful lot of detail even at sensible levels, and for the most part that is what I appreciate and to which these comments refer.



atc scm19a back panel



Bass is particularly pleasing, it has almost as much subtlety as the mids and highs, so even quiet bass notes are fully realised, have depth and shape. This means that the music as a whole is more complete, the lower octaves may not extend as far as a bigger active but they are far cleaner than most passives, almost regardless of how much power you throw at them.

There are times when I think that I can hear the limitations of the power amplifiers, when a veiled greyness creeps into the sound that I associate with more affordable electronics. But then when I change something in the source it’s gone and I realise that I’m hearing what’s being produced further back in the chain. The listening was done with a Townshend Allegri passive controller via a Music First transformer adapter to get the XLR connection. It might have been better to use a preamplifier with balanced output but the Allegri is very hard to beat.

I tried a number of sources including an Innuous Zenith MkII (a rather good SSD equipped music server for under £2k), this delivered Radiohead’s Moon Shaped Pool in highly articulate fashion, revealing the intensity of the song ‘Burn the Witch’ and the undercurrents running through ‘Daydreaming’. There is always something interesting to latch onto with this speaker, you can listen right into the mix and pick out what’s going on while at the same time enjoying the music’s drive and solidity. Imaging is surprisingly good on this album considering the absence of much in the way of a natural acoustic; it infers that placing three dimensional sounds in a room is not the exclusive domain of purist recordings. I really enjoyed the Radiohead, it’s hardly audiophile fodder but it’s clean, reasonably dynamic and works well at higher levels. A cleaner sounding album is Lumen Drones’ debut on ECM, an unlikely example of Velvet Underground inspired Norwegian post rock complete with Hardanger fiddle, that reveals the crystalline nature of its recording thanks to a near silent ‘noise floor’.



SB75 150SL 1



Placement wise I found that the SCM19A worked well closer to the wall than average – that sealed cabinet means the majority of the bass comes from the main driver and benefits from a bit of rear wall enforcement. The imaging works well once you find the right spot and give the speakers a toe in toward the listening position. This lets you hear the assured nature of great playing as found on this occasion from the fretless bass, Spanish guitar, piano and electric guitar on Bugge Wesseltoft’s OK World, the instruments being rendered with depth and presence, their dynamic excursions given free rein by the ATC’s plentiful headroom. I love the speed of tabla playing they reveal on the track Sharanagati, and when the drums and bass kick in, a real pressure wave hits you. Music is a physical and an emotional experience, and you need a bit of muscle to deliver it in full.

Every change you make to the music and to the system is reflected in the results, a Rockna Wavedream DAC helped the speakers to disappear from the aural picture, a trick enhanced by Townshend Seismic Platforms used to isolate them from the wooden floor. Playing classics like Astral Weeks (Van Morrison) you can hear all the string overdubs in the context of a musical flow that is absolutely transcendent. The digital version of this remarkable album can sound thin on occasions but the SCM19A avoids that by pulling out the plucked double bass line that is the key to the rhythms that underpin tracks like ‘The Way Young Lovers Do’.

I could go on but hopefully the crux has been communicated, this ATC like its range mates is not designed to elaborate on the signal, it exists to let you hear it like it is. In this respect it sounds more like a studio monitor than your average domestic loudspeaker and what this does is focus on the playing, singing and performance rather than the sound. So ATCs are speakers for music junkies, especially those who like their music at the same sort of sound pressure levels enjoyed by many musicians. They are a blank canvas at the mercy of the signal, get that right and you have an unusually good loudspeaker, one that will keep you enthralled to the end of every album.


Drivers: HF ATC 25mm dual suspension Tweeter, Mid/LF ATC 150mm SL

Matched Response: +/- 0.5dB

Frequency Response (-6dB): 54Hz-22kHz

Dispersion: ±80° Coherent Horizontal, ±10° Coherent Vertical

Max SPL: 108dB

Crossover Frequency: 2.5kHz

Connectors: Male XLR

Input sensitivity: 1V

Filters: 2nd Order critically damped with phase compensation

Overload Protection: Active FET momentary gain reduction

Fault Protection: DC fault protection and thermal trip. Fault indication on rear panel mounted LED

Amplifier Output: 150W LF, 32W HF

Dimensions (HxWxD): 980 x 370 x 344mm 

Weight: 31kg
Finishes: black ash, cherry, black, white

Price when tested:
Manufacturer Details:

ATC Loudspeaker Technology
T +44 (0)1285 760561


floorstanding active loudspeaker


Jason Kennedy

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