Hi @capslock,Excuse me if this has been addressed before. How does this graph square with the a 330 Hz (some older data sheets say 400 Hz crossover frequency as specified by KEF?
This looks more like a 190 Hz -6 dB point = XO frequency to me.
Edit: I wondered if with the measurement below being nearfield the far field would look different due to baffle step. However, with its 20 cm baffle width, the drop from baffle step would start at a much higher frequency than either 190 or 330 Hz. I would also assume this was measured with the crossover in place, but it looks like the regular closed box 12 dB/oct drop off of a MF driver in a sealed compartment. Very confusing!
Bonus question: why is the XO frequency all over the place with R3, R5, R7 and R11, with no correlation to LF size or overall speaker size?
View attachment 419958
Nearfield measurements are useful for isolating the effects of each individual driver, but they aren't quite correct in the crossover region. This is because many drive units will be sounding simultaneously, and the measurement will only be in the nearfield for one of those drive units. Our crossover specifications are based on sectional, anechoic farfield data. For the R11 Meta, this can be seen below.
This shows the true response of the drive units, including positional and radiative information (drive location and baffle step etc.), that the nearfields don't capture.
Nearfield measurement has become standard practice in measurement-based reviews, as it does show the behaviour of an individual driver without messing around with the crossover.
On the other point about the difference in crossover points, I can't comment from my own experience, as I didn't design this range. However, a lower LF/MF crossover point for the larger speaker makes sense to me. This would be due to the large LF "source size" - the drive units are more spread out. This gives a narrower radiation than for a closer spacing of drive units. Therefore to give a smooth transition to the midrange, the LFs must be crossed over lower than if the drivers were tighter positioned. This is why blade is so good, the drive units are close together, so we can cross substantially higher, while still getting the correct directivity profile.