![metric halo fuzzmeasure metric halo fuzzmeasure](https://www.kimlengaudio.com/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/3/_/3_1_20.jpg)
![metric halo fuzzmeasure metric halo fuzzmeasure](https://www.scvdistribution.co.uk/files/MH_2882_2D.png)
The crossover frequencies are close to those specified, and all the acoustic crossover slopes appear to be fourth-order. The port is tuned to a low 26Hz, this revealed by the notch in the woofers' response at that frequency, though its output peaks rather more broadly than I expected. The magenta trace in this graph is the lower-midrange unit's response, measured in the nearfield below 400Hz, and, in the farfield, on the tweeter axis above that frequency the black trace is the coaxial Uni-Q tweeter's farfield response, again taken on the tweeter axis. The traces in fig.3 show the summed output of the ports (green trace), the summed output of the twin woofers (red), and that of the lower-midrange unit (blue), all measured in the nearfield. The cast-aluminum high-frequency enclosure was completely inert.įig.2 KEF Reference 207/2, cumulative spectral-decay plot calculated from the output of an accelerometer fastened to the center of the main cabinet's sidewall (MLS driving voltage to speaker, 7.55V measurement bandwidth, 2kHz). Given how difficult it is to minimize panel resonances in large speakers, KEF has obviously paid careful attention to the 207/2's cabinet construction. In fact, the only mode I could find was on the center of the curved sidewall at 223Hz (fig.2), but even this is well down in level.
#Metric halo fuzzmeasure free#
The impedance traces are free from the small discontinuities that would indicate the presence of panel resonances. Something that will be a factor, if the KEF is used with a tube amplifier having a fairly high source impedance, is that the impedance peak in the presence region will tend to make the speaker sound a little bright with such an amp.įig.1 KEF Reference 207/2, electrical impedance (solid) and phase (dashed). Certainly the phase angle is generally low, meaning that the speaker should not be that hard to drive, even with its 4 ohms impedance magnitude over much of the audioband. The absence of the usual double impedance hump in the bass implies that KEF has used some sort of conjugate network at low frequencies in order to make the speaker resemble a resistive load. But also like the earlier version, the 207/2's impedance averages 4 ohms throughout the bass and lower midrange, with a drop to 3.5 ohms in the high treble (fig.1). Like the original KEF Reference 207, the Reference 207/2 has a voltage sensitivity that is significantly higher than average, at an estimated 91dB(B)2.83V/m, as specified.