7/23/2023 0 Comments Kef ls50 meta surround systemFigure 5 details the CEA 2034 results.ĬEA 2034 defines the listening window as an average response of nine frequency response curves within the 10º vertical and 30º horizontal angular range. At these same frequencies, the system is quite even from left to right as seen in the horizontal mapping. Of course, your room influence will compensate for some of this difference and, accounting for the CEA 2034 vertical listening window, fall well within 10º. This would indicate a perceptual difference in low frequency, say kick drum or bass, from sitting on axis to standing and at 3 meters. The frequency response is almost identical to the horizontal radiation map with the exception of an asymmetrical loss between 100Hz and 180Hz and at -100º. As the head moves up, we are going up and over the cabinet, and conversely down underneath the cabinet and to the back at 180 degrees. Here we are examining the vertical cross-section from the perspective of the left side of the cabinet. The vertical contour map below bears this out (Figure 4). The beauty of a coaxial system is the symmetry from horizontal to vertical. With the ports open, an additional 1dB to 2dB in gain is encountered at 40Hz. Again, this analysis is based upon the ports being closed on the system. Another slight dip in response is encountered from 250Hz down to 150Hz where the pressure level recovers and then drops off gradually to 40Hz. This should result in an even and relatively wide listening widow though the vocal region. The radiation pattern is good up to 30 degrees off- axis and to a 6dB down point. At 3kHz, a 2dB to 3dB dip in frequency response is encountered but this recovers at 1.5kHz. As it moves right (or up in the graphic), it is experiencing the frequency response and radiation around the right side of the speaker.Īs a co-axial system, frequency response on-axis is very good from 18kHz down to 3kHz and for a 40 degrees angle. As the head moves to the left (or down), it is moving to the left around the speaker until the point it reaches the -180º position on the X-axis and behind the speaker. The unwrapped horizontal contour map is an examination of the frequency to radiation strength in a “top-down” fashion (Figure 3). Even 30º offaxis, the frequency response holds together very well.įigure 4: Unwrapped vertical contour balloon, 3m. This might result in a slight reduction in definition, but considering the -1dB to -2dB in level, and the increase at 4kHz, sibilance doesn’t suffer greatly.Įxamining the off-axis frequency response curves at 15º this co-axial system holds together admirably (Figure 2). Taken as a whole, the complete frequency response exhibits a 2dB variation throughout most of the range, with a dip that spans 1.75 octaves, from 1kHz to 3.5kHz. Another peak is then encountered at 16kHz where the device rolls off to its measurement limitations. At 3.5kHz, we see a 3dB rise ending at 10kHz, where the frequency response gradually descends 2.5dB ending at 11kHz. Please note the Y-axis, 5dB scale, which translates into a 2dB range of unsmoothed deviation within these frequencies. Horizontal On- and Off-Axis Frequency MeasurementsĮxamining the frequency curve on-axis, the LS50 has an impressively smooth response from 135Hz up to 3kHz. Figure 2: Horizontal sensitivity is measured on-axis at 15º, 30º, 45º, and 60º (no smoothing).
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