The tweeter is also well behaved, though its top octave is plateaued down by 3dB compared with the region between 4 and 11kHz. Moving higher in frequency, the woofer is well behaved in its passband before crossing over to the tweeter close to the specified 2.8kHz. A slight bump visible in the upper bass will be due to the nearfield measurement technique, but the woofer alignment appears to be a touch on the overdamped side, favoring control over richness.įig.3 ATC SCM 11, acoustic crossover on tweeter axis at 50", corrected for microphone response, with nearfield responses of woofer (blue) and port (green) plotted below 350Hz and 1kHz, respectively. Fig.3, which shows the individual responses of the woofer (blue trace) and tweeter (red), confirms that the speaker's bass output is ≦dB at 53Hz. The peak of 52 ohms at 53Hz in the impedance plot suggests that this is the tuning frequency for the SCM 11's woofer, which will be the frequency at which the response lies 6dB down from the midband reference. As I've written before, all things being equal, a sealed-box design will give a more extended low-frequency performance in-room than a reflex (ported) design, due to the former's slower rolloff below resonance: 12dB/octave rather than 24dB/octave. The SCM 11 is somewhat unusual in having for its woofer a sealed-box alignment. It's possible that these modes are high enough in frequency to have no subjective consequencesJM certainly didn't remark on any midrange congestion that might have been laid at the door of this behavior.įig.2 ATC SCM 11, cumulative spectral-decay plot calculated from output of accelerometer fastened to center of side panel (MLS driving voltage to speaker, 7.55V measurement bandwidth, 2kHz). There is a slight discontinuity between 500 and 600Hz in the impedance-magnitude trace, and an investigation of the enclosure panels' vibrational behavior with an accelerometer did uncover two fairly strong resonant modes on the sidewall in this region (fig.2). Though there is a rather demanding combination of 5.5 ohms magnitude and ≤2° electrical phase angle at 3.3kHz, this shouldn't overtax well-designed amplifiers.įig.1 ATC SCM 11, electrical impedance (solid) and phase (dashed). This was probably owing to the fact that the SCM 11's impedance remains above 8 ohms for most of the audioband, with a dip to 6 ohms between 100 and 300Hz, and to 4.8 ohms in the mid-treble (fig.1). I estimated the ATC's sensitivity as being a low 82dB(B)/2.83V/mthis speaker should work best with higher-power amplifiers, though I note that JM had no drive difficulties with the Arcam Mini or Carat I57 receivers he used, and was impressed by the speaker's dynamic capabilities when he drove it with the Peachtree Nova. “For the money and putting my experience and word on the line the ATC SCM11 are at the absolute top of their class and you really would have to spend much more to even be able to stand up confidently against these awesome little speakers let alone better them.The SCM 11's voltage sensitivity is specified as a fairly low 85.0dB/2.83V/m this seemed a touch optimistic, as the ATC didn't seem to play any louder than the sample of the BBC LS3/5a that I routinely include when I'm set up to measure a bunch of loudspeakers. “ I’m stunned by their clarity, resolution, and definition across the audible band, but especially in their ability to reproduce accurate bass…” - Stereo Mojo “…I suggest that you listen to a pair of ATCs, if it’s this pair all the better because you’ll struggle to find more musical thrill power for your money elsewhere.” - HiFi Wigwam This isn’t just a step up – it’s a running leap.These are the most talented standmounters anywhere near this price.” - What Hi-Fi "Best Standmounter Award " - ATC has raised the bar it set itself. ” This is a killer product.” - Hi-Fi Choice. Stereophile 2014 Editor’s Choice Award Winner. Has heard” - The Absolute Sound, 2015 Editor’s Choice Award Winner. "A superb and superbly defined midrange, overall tonal neutrality, broad-shouldered micro- and macro-dynamics are all in evidence.
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