Are first order crossovers best?

I'm only guessing here. Perhaps because some cables purport to maintain absolute phase better than others. Only single driver and 1st order cross-over speakers maintain absolute phase. Of course the skeptic might say that sellers feel the need to provide a reason for all the cable options and a means to qualify their suggestions.

Unsound you're partly correct on the 1st order=correct phase. Until recently I thought all 1st order crossover speakers maintained correct phase.To my dismay there's a couple of imposters in the group.Sonus Fabers and some Dynaudio speakers have their tweeters and midrange drivers wired in/out of phase or the bass drivers are wired in/out of phase.The drivers in these speakers aren't all wired in positive polarity together.

I think that's one of those things that boil down to a matter of taste. Most people in audio are trying to build a system that serves their music, and gets out of the way. Some people are disturbed by phase errors or certain types of distortion, and some consider these acceptable trade-offs.

I personally prefer time and phase coherent speakers, although I have none in-house right now. I was raised on Vandersteens, and these kind of speakers just seem to serve the music better over the long haul. Of course there are only a few companies making this kind of speaker, now that Meadowlark is gone. The parameters that are needed to make a first-order speaker go are more limiting to a designer than than say fourth-order ones.

No crossover is the best.. Even an Active vs. passive all together is better. But for your question, I think most of the speakers with first orders do for some reason sound more natural and effortless vs. other slopes.

I started a thread on this a while back which turned into a sometimes heated and very informative discussion. I'm no computer whiz so I don't know how to locate the thread and provide you with the link. But I bet someone, perhaps yourself Blindjim, can locate it and I would recommend you do. I heard from everybody from Jeff Joseph of Joseph Audio (who uses very steep 4 order filters) to the guy from Green Mountain Audio (can't remember his name but a proponent of first order designs). Also, check out Richard Hardesty's "Audio Perfectionist". He adheres to the first order mantra. After much reading and reflection I came to the conclusion that you need to design the crossover to work with the drivers you have selected and the overall design. This is much more important than phase coherence. Can even the best drivers operate far outside their natural frequency response limits in a 6db slope design--I have my doubts. Should all drivers be shut down radically so they operate within a fairly narrow range of frequencies--I don't think so either. I am of the opinion that the dogmatic approach (i.e. must use first order, must use 4th order) doesn't make a lot of sense. Rather, the crossover should be tailored and tuned specifically to complement other aspects of the design (intended use, drivers, bass loading, etc.). Of course I'm no expert and you should read some of the literature out there for yourself to form an opinion.