LABORATORY TEST RESULTS
Newport Test Labs measured the in-room frequency response of the Krix Acoustix Mk2 as being 58Hz to 40kHz ±3dB (as shown in Graph 1) which is an excellent result. However, if you look carefully at the graph you can see that the 58Hz –3dB limit came about due to a tiny dip at this frequency and that the response actually rises a little below 58Hz and then extends down to around 48Hz before again dropping to –3dB again.
As you can see, the overall response is balanced, so that within the ±3dB allowed variations in response, there is no spectral skewing to favour one frequency band over another. The response does roll-off slowly above 10kHz, but does so only very slightly. There are minor discontinuities in the response around 1–1.5kHz and between 2.5kHz and 4.5kHz, but the variations are in the order of ±1dB, so are really of academic interest only, as they would not affect the sound quality.
The protective grille has been well-designed, and is almost totally acoustically transparent, but you can see from Graph 2 that the response of the Acoustix Mk2 is slightly flatter without it. However, even with the grille fitted, the high-frequency response still fits within the ±3dB specification save for two small suck-outs that are well above the limit of human hearing, at around 28kHz and above 35kHz, so I would recommend listening with the grilles fitted at all times.
Graph 4 shows the low-frequency response of the Krix Acoustix Mk2 via a near-field technique that simulates the response that would be obtained in an anechoic chamber (so not an in-room response). You can see that the bass/midrange drivers roll off quite rapidly below 100Hz and the ports’ output peaks at 51Hz. The ports’ output rolls off slowly to 500Hz. There is a little unwanted output from it up around 1.5kHz, but it’s more than 20dB down, so of no concern.
The measurements prove the Krix Acoustix Mk2 to be a very well-designed loudspeaker
Krix puts the nominal impedance of the Acoustix Mk2 at 8Ω, but looking at Newport Test Labs’ measurement (the red trace on Graph 4), I’d put it at 6Ω. And whereas Krix claims a minimum impedance of 4.3Ω, it looks to me more like 4.5Ω (at 200Hz) from the trace. The position of the ‘saddle’ between the two resonant peaks suggests that there will be little usable output from these speakers below 52Hz. There is a small discontinuity in the impedance trace at around 4–5kHz that was present on both loudspeakers and corresponds with the tiny lift in the frequency response that’s visible on Graph 1 and is possibly indicative of a minor resonance.
Newport Test Labs measured the sensitivity of the Krix Acoustix Mk2 as being 86.5dBSPL at one metre, for a 2.83Veq input. This is almost 3dB shy of Krix’s specification of 89dBSPL. Newport Test Labs’ measurement methodology is tough on small speakers, so 86.5dB would be a ‘worst-case’ scenario, but conversely, I think the Krix’s 89dBSPL spec looks a bit optimistic. That said, 86.5dB is a very good result for a small speaker.
Overall, the measurements Newport Test Labs made of the Krix Acoustix Mk2 prove it to be a very well-designed loudspeaker.
Readers should note that the results mentioned in the report, tabulated in performance charts and/or displayed using graphs and/or photographs should be construed as applying only to the specific sample tested.