Interesting that on the 3 way they use a 15” cone all the way up to 1100 hz, and that they cut off that driver below 200 hz (prob to avoid IM distortion).
First of all, thanks for the response! I have seen several criticism towards coaxials as lacking in dynamic range and not the best option for content that is not strictly, music (cinema, games...). This criticism feels strange as coaxials like KEF´s have been marketed as all-terrains and even adapted to home theatres for decades.There are various ways to get mids close to tweeters to reduce lobing and control directivity: Synergy horn, coax, small mids flanking tweeter in a waveguide, as in Perlisten. They differ in detail and in execution, but they are all trying to skin the same cat. One of the major differences is with regard to horizontal beamwidth. Some like it wide, others narrower for small rooms. I would think the Perlisten approach tends to produce a wider beam; synergy approach tends to be narrower and by intention. with coax's, directivity depends on the shape of the woofer's cone.
In a 3-way this should be mostly a non-issue since the crossover will be in the hundreds of Hz, even for a smaller coax you can limit the excursion to within 1 mm or so for a high enough SPL.^ also the woofer makes environment of changing pressure for the tweeter, and the tweeter works as microphone modulating the electronic parameters for the sound its bandwidth perhaps causing some distortion. Not sure what the magnitude of such "issue" is though. Minimized with high pass filter.
The modulation has mostly to do with the excursion, and far less with the surface area. And since you need 4x the excursion for the same SPL for half the diameter, this adds up fast.Question. If I have two coax drivers and one has half the woofer cone area of the other, will the IM distortion of the larger one be lower or the same at the same Spl? If the product of cone area times excursion is equal, does that make IM equal?