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Seeking "Crossover Networks For Dummies," please

Hello, Gang,
I would very much like to read a thread which is a kind of primer on speaker crossover networks. I do understand that this topic encompasses a lot of complicated material, including electronics and physics!
Still, I'd like to know more about this topic. It would help me to understand some of the opinions and controversies I've read here over the years.
What factors or "philosophy" might cause the designer to choose, say, a second order network over a first order network? I've seen people on this forum post things like, "I cannot listen to anything other than a totally time coherent and phase coherent, first order network." On the other hand, there are much loved and highly regarded speakers out there that use second order and fourth-order networks!
Anyway, I'd love to understand more about this topic.
Thanks!
rebbi
drew_eckhardt
394 posts
 
> "monotonically increasing directivity index"?

> I assume that directivity increases with frequency, but I am unsure what is meant by "monotonic" in this context. Can you shed some light?

Monotonic means that it never decreases along the way resulting in broader dispersion before narrowing again (this is an audible problem with most 2-way speakers).
martykl
3,563 posts
 
Thanks.
ngjockey
1,042 posts
 
Wiki is a good place to start and the reference links seemed unbiased.

http://en.wikipedia.org/wiki/Audio_crossover

Never understood the "time and phase coherent" argument myself when one side is 90 degrees out of phase and all the other positioning and design issues. I wouldn't presume to argue with Dunlavy and Thiel and I've heard their remarkable results but I've also heard enough to know that a complex question deserves more than simple dogma. The simplest is to keep the xovers beyond the vocal frequency range, where our ears are most sensitive and wherever those lines are drawn, but that's rarely practical and involves other compromises.

Inductors are probably the worst offenders in passive xovers and they get correspondingly bigger for lower frequency, low pass filters.
rebbi OP
1,319 posts
 
Ngjockey,

Thanks for the pointer to that Wikipedia article. It's a little over my head in places, but still taught me a lot.
orpheus10
5,988 posts
 
If dummies are smart they will leave crossovers to engineers. If you buy a speaker kit, the crossover will be contained. If you attempt to build your own speaker, you will discover how complicated crossovers are.
More to discover