A Ground Breaking Investigative series! *
Dispersion of speaker drivers and crossover frequencies in speakers is bothering me a lot lately. It really bugs me that in expensive speakers 6 inch drivers and a growing number of larger drivers are very often crossed over in the 2.5KHz range. It's a general rule that a drivers dispersion pattern narrows to about 90 degrees at the frequency where the diameter is equal to one wavelength. For 2.5KHz , that means 5.4 inches. Sure, if you sit in an anechoic chamber, with the speakers facing you, who cares? In a normal room, dispersion patterns play a large role in how you hear those esoterically named things like "soundstage" or "space" around instruments. With uneven responses to dispersion over the drivers spectrum the instruments will seem to "displace" within the space depending on the instruments frequency output. With regard to center cones, waveguides and alternative materials with different breakup modes - while they may help, a quick look at the in depth measurements from Stereophile among other sources will show you that with oversize drivers there is, in the end, a bad dispersion range. Same trouble for all of those 1" dome tweeters, no matter how fancy the waveguide or materials, etc, once past 10KHz things are going to get lossy on the sides real quick. If you're living in a anechoic chamber, who cares? I'm not living in one. Having some frequencies dispersed at 120 degrees or more and others at radically different dispersion angles equals overall room disparities. So, don't just blame your room for "room" problems, your speaker is often just as much to blame.
So why the big move towards two way speakers with even larger mid/woofers, real big midranges, and no super tweeters?? Dynamics is the quick answer. Louder. Cheaper is the second answer, two drivers, instead of three or four. Cheaper. Don't get me wrong, there are many great speakers out there with just such disparities that sound fantastic. They need just the right room.
*Well, just a silly rant actually.