Time coherence - how important and what speakers?

Roy,
I have read the entire thread again (whew), and I have a few questions:

1) the detractors of time coherent designs almost always mention: dispersion characteristics, smoothness of power response, distortion,wave interference, off-axis lobing, and compression. I think you touched on wave interference and off axis lobing, how about the rest? Can a 1st order crossover based speaker be good in these areas or are they mutually exclusive? Can a 1st order crossover based speaker compete with the best 4th order based speakers in these parameters?

2) someone in this thread mentioned that crossovers, 1st order and others, can be implemented in series or parallel. Can you talk a bit about the pro's and con's of either implementation in a 1st order crossover?

Thanks. This is one of the best threads on the Gon! My audio wish, lol, would involve getting other knowledgeable people like yourself involved in this thread. Here is my dream team, in no particular order:

1) Roger Sanders
2) Richard Vandersteen and/or Pat McGinty
3) Alvert Von Schweikert
4) Joe D'Appolito or Floyd Toole

Now THAT would be a discussion. Who can make this happen? Maybe we can collectively e-mail these individuals to encourage a dialog to help eductate the supporters of this wonderful hobby???? I would pay to see/read it :)

Dolphin ... add John Bau (Spica) to that list.

Dolphin..also add Jim Winey of Maggie fame...hey...have to have a planar guy in a speaker discussion...even if his products are "out of phase"!

hello, perhaps this is somewhat of an off topic question, concerning crossovers I have been under the impression that a 4th order linkwitz-riley electronic crossover was a far superior choice for auido production/reproduction of music, especially due to phase and time matching between adjacent drivers. For an excellent source of info on this: http://www.rane.com/note107.html I realise that the thread has been mainly about less complex systems, such as a simple pair of commercially available speakers, or the same with a sub/s. But even a 5 way crossed over system comprised of 2 stacks of loaded cabs is really nothing but a complex 5 way speaker system. Any comments will be well appreciated, thanks

4th order LR does have the benefits described. It should be noted that your particular link seems to be talking mainly about ACTIVE crossovers, meaning (typically) op-amp based electronic filters placed upstream of the power amps. This is an absolute piece of cake compared to designing proper passive crossovers, but very few speakers on the market go this route as it requires an amp for every driver, and makes the overall package pretty spendy. ATC does a great job at this, but their market share is pretty low overall because most people want to be able to mix-n-match their amps and speakers (I'm not saying this is a better approach, quite the opposite, merely that it's what most people seem to want). Implementing an ACCURATE 4th order L-R in a passive crossover with real-world drivers and all their problems is a giant headache, to say the least. Lots of manufacturers will claim to be using this type, and they are in a theoretical sense, but in fact the end result isn't a truly accurate 4th order L-R due to the frequency response/ impedance/ phase variations in the drivers themselves. They can sometimes come close, but the end result is never ideal like it can be when using op-amps. This is why active crossovers are such a piece of cake by comparison.