Do aftermerket crossovers improve sound?

The simple and straight forward answer is yes. Speaker manufacturers neglect the internals of speakers when they are trying to keep costs down. They know the 90% of people aren't even going to look inside.

Even if you just replaced the critical parts on the xover, it would be a great improvement. When I upgrade xovers, I focus on the high and mid parts, a lot less to be gained from the low portion of the circuit. Furthermore, I typically just swap out for like values, and only on ocassion, do I bypass caps.

Bottom line, it's right up there with the best money you'll spend on audio.

Give Bill Legall of Millersound a call to see what he can do for you;he is one of the most regarded people in the industry for speaker repair and crossover redesign.

Shadorne amazes me how much folks pay for cheap transducers and poor measuring crossover parts. As long as it has the right brand name or had a + review fancy veneered of coarse. I see many 15k loudspeakers with $50 tweeters. In our KCS 17K model we offer fostex amk2 a $1550 tweeter set. Our capacitors cost more than most all parts used in out competitors loudspeakers. But your right many folks do not buy on quality of design and parts just on validation. There loss.

Ya, you could go active but that would require multiple amps or a multi-channel amp (Accuphase and Ayre come to mind) and the 802's are not an easy load.

http://home.netvigator.com/~goneill/bw.htm

Too late...

http://cgi.ebay.com.au/Accuphase-F5-crossover-350%2F2.5KHz-for-JBL-B&W-801-802-_W0QQitemZ220557442619QQ

Northcreek claim that B&W use a ferrite core inductor in the crossover. B&W have indeed been cutting corners in order to keep costs down. Most manufacturers will cut cost on drivers and internal parts (the bits you do not see) in order to increase margins and spend more on veneer and external aesthetics (what you see & are willing to pay mor for).

Since most people hear what they see - this works eminently well.

It is well known that ferrite core inductors are non-linear and can even saturate - they are found in many speakers but a large expensive air core inductor is definitely preferred for high end applications where linearity is important.

Better still - get an active speaker and get rid of the crossover capacitor non-linearity and power losses too. A passive crossover is a bad idea unless you don't mind the power losses and distortion that it introduces.