For a few analyses, I
took the horizontal measurements from the LXmini and scanned them. I cannot exclude small errors during scanning, but on the whole the frequency responses should be correct. The 15° frequency response below 500Hz seems to have been affected by ambient noise, have treated this frequency range as 0°.
Unfortunately, there are no vertical measurements, which would certainly have been particularly interesting due to the driver positioning.
For all comparisons, especially with those based on NFS measurements (from Amir or Erin), please note that the LXmini measurements are heavily smoothed and therefore appear much smoother.
So, first the frequency responses from 0° to 90°, as they are also shown on Linkwitz's website.
Then the frequency responses are normalized to the on-axis frequency response.
Up to 1 kHz there are no conspicuous characteristics. It behaves as would be expected from a sealed speaker. The low influence of the cabinet has a positive effect; the radiation is very even up to 1 kHz.
When the Seas full range driver (crossover 900Hz) takes over, the radiation narrows down considerably. This is the transition from monopole to dipole.
Now let's look at the directivity of the speaker +-90° and estimate the horizontal constant coverage.
To do this, we look at the sonogram normalized to the on-axis FR and the -6dB limit:
Above 1 kHz, the radiation narrows considerably in several steps. If you consider the -6dB limit above 2kHz, you get a constant coverage of about +-40° (80°). It is therefore a narrow, rather than wide, radiating speaker. This is similar to the radiation behavior of a small horn.
Where's the magic in that?
It becomes "special" when you look at the directivity +-180°. For this purpose, we look at the horizontal normalized sonogram (+-180°)
Now you can see a narrow side lobe that forms behind the loudspeaker (look at the respective edges of the diagram at +180° and -180°) and that possesses appreciable sound pressure level in the range 1.2-5kHz.
If we look at power response and directivity index in the
horizontal plane, the graph is choppy, but smooth on average. In part, erratic changes are included, which is actually not desired.
Update: But with the help of DSP, you should be able to compensate for some of this.
For comparison, with a "normal" speaker this would look something like this (only horizontal FR's too):
Seas FU10RB full range speaker used
I only know a review in
Hobby-Hifi 2012-3 about the Seas FU10RB full range speaker.
The most striking thing is a resonance around 1.5 kHz, which can be seen in the impedance measurement and in the CSD in the review. Probably a cone or/and surround resonance.
This resonance causes a peak in harmonic distortion with 5% HD2 around 1.5kHz@90dB. This is unpleasant, but only affects a narrow frequency range.
The frequency response is linear for a full-range driver and has only minor breakup resonances in the high frequencies. Rather early sound pressure level drop in the high frequencies >10kHz.