Why not go crossover-less?

A well-accepted and desirable configuration! Most active speakers work exactgly that way.

Kal

But you lose flexibility, you have to chose the drivers and then design the crossover for them. You will not be able to use other speakers without modifying the crossover. This is why this approach, despite advantages, has never taken hold. Most audiophiles middle name is change and this renders it very difficult.

For bass xovers, particularly hi-pass, it really helps and usually adds flexibility but it also means biamping, one way or another. The payoff for mid/treble xover isn't as significant because the passive components are much smaller.

Could the following be another reason the cross-over is placed in the speaker? When the x-over is placed in the line stage is it more likely that errors will be more pronounced because of the amplification of any errors? We are hearing improvements to our systems when changing the speaker caps, which obviously means the caps are contributing their sonic signature. Will there ever be a sonic-less cap? Can line-stage cross-overs be made that influence the sound less?
I found the speaker that'll stay with me for a very long time, I also found which amp I will use to drive them. If a dedicated cross-over was to be designed knowing the input impedence of the amp and output of the preamp could the line stage cross-over outdo the other approach the speaker cross-over way?

A crossover in the line stage means using at least 2 amps, you can't feed 2 signals to the same amp.

I planned on using two amps, same name less power.

Could the following be another reason the cross-over is placed in the speaker? When the x-over is placed in the line stage is it more likely that errors will be more pronounced because of the amplification of any errors?

No, the signal gets amplified as well, so any "error" introduced by a crossover that is in front of the amplifier will remain in the same proportion to the signal after amplification.

I found the speaker that'll stay with me for a very long time, I also found which amp I will use to drive them. If a dedicated cross-over was to be designed knowing the input impedence of the amp and output of the preamp could the line stage cross-over outdo the other approach the speaker cross-over way?

It sounds like you are referring to a passive line-level crossover. That MIGHT be within reason for a speaker requiring a simple first order crossover network (6db/octave), or perhaps even a second order network (12db/octave). However, anything higher order or more complex than that is likely to result in excessive signal loss. There would also likely be an unreasonable degree of sensitivity to cable parameters.

And more fundamentally, who is going to create this dedicated design? There are at least three, and perhaps four parties involved (if the preamp and power amp are manufactured by separate companies): The speaker designer, the amplifier designer, the preamplifier designer, and the user. The only party likely to have a complete understanding of the crossover requirements is the speaker designer, and he would have no incentive to create a crossover design that would only work properly with a particular set of electronics (unless of course, it was part of his own active speaker design).

An active line-level crossover, on the other hand, would eliminate the signal loss issue, greatly minimize the cable sensitivity issue, and potentially provide enough flexibility to be a viable option with some speakers. But of course it would add a costly component to the system, which would still be unusable with many speakers.

Regards,
-- Al

Something like this?:

http://www.tactlab.com/Products/MS2150XDM/features.html

>Would there not be an advantage to place the crossover in the linestage instead of the speaker?

Other than marketing there's no good reason not to. The cross-over function doesn't change with output level; you can use all-pass filters to match phase independently of baffle configuration; you get the same peak output level with smaller heat sinks and power transformers; big inductors get replaced with low wattage resistors (not $.10 each in small quantities with 1% tolerances), and big capacitors small ones (under $1-$2 for 2% tolerance film caps) due to the higher load impedances. Even when starting with your existing amplifier, an active cross-over+power amp+power supply can cost less than the large high-quality reactive components needed for a passive cross-ove.r

More accurate, more headroom, and lower total system cost.

My main system is actively tri-amplified, the small bedroom setup actively bi-amped until I get enough shellac on the new woofer enclosures for the tri-amp upgrade.

>Could the following be another reason the cross-over is placed in the speaker?

It's placed in the speaker because the output transformers and vacuum tubes which go into amplifiers are expensive and the speakers which play loud with single ended triode amps don't need the extra headroom in a home environment.

Without output transformers and tubes it's more a matter of tradition, marketing, and inertia.

If you're concerned about how accurate the transfer function is, the active solution is a lot better because the filters operate into purely resistive loads which don't change with output level (thermal compression) or driver position (Things like voice coil inductance actually vary).