Why aren't component active XOs more popular?

Well, first, answering that active crossovers are superior does not address the question posed: Why aren't they more common?

And active crossovers are not the best solution for every budget or speaker or circumstance, particularly if not included in the design from the ground up, a distinction the thread has already touched on. Actively driven speakers have never done that well with consumers for these and other reasons despite their many technical advantages over passively driven ones, all other things being equal, to take a near cousin example.

>Of course if you open up your speaker and find an overly complex
xover you know one thing for sure: The drivers are not really suitable to run
together! If you know the optimal operating range you already know
the necessary slopes and crossoverpoints.

This will come as news to Thiel, Vandersteen, many of the Joseph Audio models over the years, North Creek Acoustics, Clements and I'm going to go out on a limb and opine also to Apogee, DeVore and old Snell Type A. So, they're all junk. I'm sure we could all go on.

I'm in the prosess of going to an active system. But will be fall time before I get it all together as I will also be rebuilding and modding my Maggies MG III . I just got a sweet deal on a Marchand MX-44 X-over, I Almost stole it. They are for sale in kit form if one has the need. But my was built by Phil Marchand. I'm learning by the ones that have gone before me with similar equipment, so it is much easier for me as they have their systems dialed in already so I pretty much copy with a little bit of fine tunning to dial it in. Suits-me I don't know if you have heard the same speaker in passive then active but I have and there is no contest the active is far superior and the passive that used to be in was a tweeked out one. I think it is not more common because because there is more work involed and some what of a learning curve and the process can to some seem intimidateing. It is not part of the plug + play world that seems so popular these days.

>Suits-me I don't know if you have heard the same speaker in passive then active but I have and there is no contest the active is far superior and the passive that used to be in was a tweeked out one.

Okay, I'd like to know what speaker you heard in both modes, because I gave a couple examples of well regarded speakers which have various functions in their crossovers that would be difficult to adjust for in an electronic crossover. Then I gave some examples of well regarded speakers which use complicated crossovers, and some of those are even time and phase aligned.

Now, if you hate all the speakers I gave as examples, fine. But your vague assertion about whatever speaker you heard in both modes does not address my point or my examples, so I am left to wonder if you understood my posts at all.

Sean and b.l.z: There is a very clear distinction between active amplifier and passive LCR networks.
First, the active circuit has much more non-linearity than the passive network, leading to different types of distortion. You get more mixing (IM distortion) with active components, and those are not directly related to the originating tones.
Secondly, most analog active crossovers are implemented with high-gain opamps, which means that the designer had to apply high-levels of feedback in order to achieve low gains (usually unity at the passband). There is a specific sonic signature to that type of circuit. Cheap implementations may have slow loop delay so the delay-induced distortion may be very crude. The high-speed opamps are better in that regard, but still - "no free lunch"...
Digital crossovers have digital issues and analog issues. Cheap implementations have all the "good" traits of digital audio, in terms of converter non-linearity, clock jitter and sometimes crosstalk of digital into the analog circuitry, which raises the noise floor. Just listen at high gain to low level passages, where the noise floor is most apparent.
Bottom line is: there are issues...
Of course passive crossovers are not a magic solution, but they may be the least of all evil. If the drivers are well matched (some brands modify drivers or develop their own) then the passive crossover can be simple and accurate.
Last thing to add about multi-amping. Splitting audio signals is a nasty thing to do. It's true that a multi-driver speaker does that too, but in that case it's a necessity, unless you accept the limitations of a single-driver speaker system. I believe most people don't.
With the passive approach we assume that the speaker designer has done a decent job and the response would be acceptable with most commercial amps. That's not always true, but at least there is a good chance this will happen.
With multi-amping, we not only split but also run different amps and cables for each "band". Each path is a different audio chain, with differences by design (like solid-state for bass and tubes for mids and treble) or due to production tollerances. So not only do you have to measure drivers and match the crossover, but you also have to consider the full chain.
It's all doable. In fact, with digital crossovers it can be measured and the filters re-calculated in real-time, like some systems adjust equalization for room modes. It's a convenient way to do things, if everything can be matched and the above issues resolved.
Don't misunderstand me. I'll agree that for some price points the active approach is a good solution. I'm not sure that's true for achieving the ultimate sound. All this is my own very subjective take on amplification.

Serus: As mentioned, my Brother went from using a 6 dB per octave passive crossover using very high grade parts in a passively crossed multi-amped system to an "antique" active crossover that was used professionally and beaten to death. After hearing the difference for himself, he pulled all of the passive parts and bought an active crossover. Bare in mind that his initial testing was done just listening to a tweeter with a cap in series vs the tweeter actively crossed at 6 dB's. Not only were the differences HIGHLY audible using even a "low grade" active crossover, there are measurable differences in amplifier performance and efficiency involved in such a situation too.

Factor in that most dynamic tweeters are far less demanding of a load on an amp as compared to a large dynamic woofer and the benefits would have been even more apparent at low frequencies.

You have to remember that the passive crossover is dealing a high level signal from the amp and the reflected EMF of the drivers simultaneously. When you use an active crossover, the efficiency of the amplifier is markedly increased due to the reduction in bandwidth. That is, the amp is no longer trying to reproduce power that ends up getting "wasted" in a passive multi-amp system. The end result is that transient response is improved, distortion is lowered, thermal stress is reduced, etc... Speed and clarity is improved in every respect. The fact that the active crossover is dealing with miniscule amounts of line level voltage whereas the passive crossover circuitry is dealing with both much higher levels of voltage and current should explain why the whole system sounds "more stressed" once those parts are introduced into the equation.

On top of that, the amp doesn't see the added reactance and phase shifts of the passive circuitry as part of the load as the amp is now in "direct drive" mode. That is, the amp sees the nominal impedance of the speaker cable and the electrical characteristics of the driver itself. As such, it is a "purer" load for the amp on top of the added benefits of active bandwidth limiting mentioned above.

Granted, some specific amp / speaker combos may sound better with a passive crossover, but that is typically because the amp itself isn't up to the job at hand. Then again, getting rid of all of the other "garbage" between the amp and the drivers themselves can also be the difference between an "inadequate" amplifier and a "good" amplifier in such a system for the aforementioned reasons. It can be a tough situation, but as mentioned elsewhere, if the drivers are good units and well-matched to begin with, anything other than an active system will degrade the sonic potential of an otherwise excellent set of speakers. Don't believe me? Try inserting a cap in series with your tweeter and see for yourself. Sean
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