- 25 posts total
- 25 posts total
Suits me: I've recently been talking to a couple people that are attempting to run active crossovers on commercially built passive speakers. The more that they dig into it, the more that they realize that this is going to be a lot of work. As such, i agree that most multi-way designs with complex crossovers are best either left alone OR simply upgrading the passive circuitry that's already there with higher grade parts. Sean
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.