The design of a perfect loudspeaker is a search for the holy grail, a mystical journey towards the unknown, and in the end hoping for some serendipity to be involved.
With the development of the new KAD K7 active digital loudspeaker system, the acoustical design became the highest priority and resulted in a fully symmetrical driver unit positioning across the acoustical axis of the speaker. A major benefit of symmetry is that it solves some of the physical limits of multi-unit speaker systems with non-coincident driver units (not physically placed in same acoustical axis). Best known limitation is the "lobbing" phenomenon that occurs when physically separated speaker units radiate sound at the same frequency, "lobbing" can be observed by the listener as mild to severe variations in sound level when moving through the space in front of the speakers.
Dr. D'Appolito has demonstrated many years ago that symmetrically placed speaker units in so called MTM (mid, tweeter, mid) configuration are able to compensate for off-axis lobbing effects that impact the sound stage at the listening position. In effect MTM speaker configurations in combination with carefully selected filter characteristics can almost completely eliminate unwanted lobbing effects in the radiating sphere of a loudspeaker.
With the KAD K7 speaker system we even went a bit further than the basic MTM configuration and applied a fully symmetrical WMTMW (W= woofer, M= mid, T= tweeter) speaker unit configuration which is able to optimize the sound beaming effect down to the lower bass regions of the speaker. The benefit of the WMTMW configuration is that it helps minimizing ground and ceiling "bounce" (unwanted reflections), because it narrows the height of the vertical sound beam while opening up a wider horizontal sound stage free from "lobbing" effects.
The KAD K7 speaker system, with WMTMW configured driver units plus carefully designed active filter characteristics, effectively creates a "sweet-zone" in the listening position where a constant level of musical sound quality can be experienced. With the KAD K7 speaker system, the usual narrow "sweet-spot" we know so well from standard speakers has turned into a significantly wider "sweet-zone", without the need for experimental positioning to find the right amount of toe-in for each speaker.
What is the best position to place low frequency driver units in your loudspeaker? Front mounted? Rear mounted? Side mounted? None of the above actually, they should be placed in the wall of your room of course. Well, that seems a bit unpractical, doesn't it?
In order to obtain a cardioid-like radiation pattern in the KAD K7 it was essential to create similar but time delayed acoustical energy able to add and subtract under the laws of superposition. When front and back firing speakers are in a "half λ" phase (physical distance D + electronic delay δ) and inverse relationship, the energy sent towards the front wall may turn to zero, whereas the acoustic energy directed towards the listening position will be maximized (up to 3 dB gain). So, now with minimized sound pressure levels reflecting off the front wall, it is possible to position your cardioid-like KAD K7's with much more freedom as before, the KAD K7 loudspeaker system in effect has become "position agnostic".