Crossovers, why so few options?

Because so few people need one. Almost all speakers have entirely adequate crossovers built into them and these incorporate custom features that tailor them for their specific drivers and enclosure(s).

Kal

The problem is that no "off-the-shelf" active crossover is really suitable for any serious loudspeaker. The crossover must be customized to the the specific speaker system in order to account for amplitude/phase issues in and out of each driver's pass-band. This means that a great deal of flexibility is required in the filters and, more critically, more sophistication is required of the user. The former can be bought but the latter demands some learning and experience.

So, in principle, using an active crossover (and not a passive inbuilt one) can afford real advantages but this is most easily realized with speakers that are designed and marketed that way.

Kal

??? Why didn't you say so??!! That's an easy one.

The reason is that such are built into most subs and into all preamp/processors. The need for an external crossover is quite limited today.

Kal

Well, this little pond is not representative of the audio world at large. Consequently, the volume demand for this type of product is limited. Some reasonable suggestions have been made. The SMS-1 is one but it is limited to only 80Hz for HP. Consider also the Parasound P7 preamp with adjustable crossover. For more complex/sophisticated installations, there are the pro and DIY markets.

Kal

Eldartford wrote: "Kal...The passive crossover elements which address driver characteristics can be retained while the basic HI/LO filtering is done at line level."

Not really a good idea. Have you considered the consequences of cascaded filters? Makes everything much more complex and difficult.

Kal