If you use an electronic XO, you are assuming the role of a speaker design engineer, having to equalize drivers to match level and phase. You then have to fine tune the sound, a process known as "voicing".
All that is obviously doable, but not that simple for the home hobbyist IMO.
Another argument against active XO is by the purist camp (not in derogatory sense!) which preaches the least processing to the audio signal as the golden path to "audio nirvana".
I have the Behringer active crossover. It made a world of difference with my maggie 3.5's. However, it was a very time consuming process to dial everything in just right. In the end it was weel worth it.
It is very difficult to get an electronic crossover system to integrate with your speaker system unless the speaker designer designs and manufactures the electronic crossover too! This would be the best match. This could be offered as an upgrade for your speakers to take them to the next level. Any designers listening? I think there is a demand here!
Thinkat and Serus summed it up. It is both more difficult and more rewarding if one puts forth the effort required.
As far as the "purists" go, i don't know of anyone that has heard a well designed actively crossed system that would choose a passively crossed system as being sonically superior. My brother was running custom built speakers with very simple crossovers using high grade parts and passively multi-amping. After i kept badgering him to try actively crossing them, he could not believe the difference.
Bare in mind that the huge increase in sonic performance that he noticed was achieved via an antique "pro sound" crossover that i had purchased years ago for less than $50 shipped. If one were to use a more advanced and better sounding crossover that allowed both time constants and contouring to be included in the processing, the benefits would be even greater.
As mentioned above though, the time and effort involved is a LOT more than what most audiophiles want to do. This approach is best suited for those that want to get their hands dirty and learn i.e. DIY rather than keep buying the flavour of the month and never understanding why things don't work like they should. Quite honestly, i've never seen a commercially designed product that wasn't built to a price point, regardless of the retail price. Sean
When done write active XO is fantastic. I use it my reference system and I think we will find more companies in the very high end moving in this direction. However, once you do active XO and get it right, you are not likely to to sell your active XO--such is the case with me. That's probably why very few used ones show up here.
I have got no idea why they are not more popular
since they are superior in EVERY way.
Most of all they allow you to remove
inductors from the signal path; I'd rather have dozens of other
components then one inductor! They ruin everything:
they blur transients, shift phase and eat at least 50% of your
amplifier power as their minimum insertion loss is 3dB!
I could very well be wrong here, but, it is my understanding that untill digital crossovers arrived one could not get active crossovers to behave like 1st order passive crossovers. One may argue that having the large driver overlap of 1st order crossoves in large measure negates the point of active crossovers. Unfortunately one would then sacrafice the potential for time and phase continuity. I am hoping that the new generation of digital crossovers wil enable us to easily accomplish all the benefits with out (much?) compromise.
Errr...with a propper electronic crossover phasing doesn't get messed up in the first place so that is not really an issue! Remember it is the passive components of standard xovers that do all the messing up, remove them
and the problems disappear.
Electronic xovers are available with any slope you like if you really must have
a first order one or your driver demand, Bryston and LCAudio come to mind.
Many already contain delay to adjust timing differences between drivers.
Phasing can also be made continously variable if you want.
This is all possible in the analog domain so no need for convertors
and all the horrors they can produce.
Even other than the standard slopes should be possible.
Thanks for all the responses. As my bro-in-law explained it to me, the active XO is just another way to get the most out of an amp and also to get the most out of a system's environment by manually controlling which components receive which frequencies.
I'm new to high end stuff but after getting to know my equipment I think this would be a fun thing to do, especially with an entry-level crossover not being very expensive.
It's not so easy to add an electronic crossover after the fact to just any system. To be brief, first you need a speaker which truly has separate crossover paths for each driver, and not just two or more sets of terminals on each speaker. Second, you need to know, or discover, any number of characteristics of the passive crossover that comes built in to the speaker, for example, baffle step compensation, zobel networks, the optimal operating range of the drivers, plus the frequencies and slopes chosen by the manufacturer (hopefully) for good reason.
In terms of sound quality, it makes no sense whatever to with entry level, non diy electronics or speakers. In terms of being able to play around...maybe it makes sense.
Suits me: Have you ever seen serious test results from most "audiophile" speakers? The mass majority aren't nearly as well designed or integrated as one might think. "Audiophile grade" loudspeakers are one of the highest profit margins out there ( outside of cabling ) with the least design integrity behind them. That's why DIY speakers and forums discussing such things are so ripe for the picking with useable information. As such, experimentation in this area can typically result in steps forward in both sound and one's sonic education. So long as any "modification" is easily reversed, there's really nothing to lose here other than pre-conceived notions and an education about modifications that many consider to be "taboo". Sean
b.l.zeebub, that's what I would have thought and both Bryston and LCAudio do list 6db crossover options. I'm sure that there is/was some sort of misunderstanding but, none other than Roy of Green Mountain has said here on audiogon that active crossovers can't achieve the results he desires and achieves without going digital that he can passively. In some case it may be that one may have to convert from the digital domain. The horror!
Sure, a lot of manufactured speakers are junk. So's a lot of diy stuff.
Anyway, here's the last two lines of my post:
>In terms of sound quality, it makes no sense whatever to with entry level, non diy electronics or speakers. In terms of being able to play around...maybe it makes sense.
What I meant and thought I said was, "It makes no sense whatever to with entry level, non diy electronics or [non diy] speakers." I thought the second "non diy" was implicit, and I could say why, but perhaps it's ambiguous.
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.
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
I am using an active crossover for my InnerSound EROS MKII
speakers and I like it bunches.
Who says they aren't popular? The reason you don't see many is once you have one in your system--You are not going to give it up! Occassionaly you will see one and they sell fast. For me the greatest single improvement was going from a passive bi-amp system to an electronically XO system. There are some caveats: With 3-way electronically XO's, (ie tweeter, mid & bass), there is a much higher probability of blowing tweeters (in my 3-way system I have blown 2 sets of tweeters in the last 5 years--and both times I did something stupid); then there's the hassle of 3 amps and the clutter of that much more cables and wires. But the sound makes it worth it IMHO. Marchand has wonderful kits for electronic XO's. You do have to set levels but this also gives you the flexibility to make it sound the way YOU like it. The other beautiful thing, is it frees up your tube amp to do the things they do best and allows you to use a solid state amp to do the grunt work of bass. And one more thing: If you are building your own speakers, designing a passive cross-over is extremely difficult. You can buy software or have someone do it for you (recommended if you must go passive) but by the time you buy first rate components, you probably could have bought an electronic XO and I think the electronic XO will sound better!
Again, I remind people that a major advantage of electronic crossovers is to reduce the power amplifier power requirement, and to avoid IM distortion. Both of these advantages have become less important with the advent of solid state power amps. For those who still use tube power amps, tube crossovers are available (for example from Marchand).
With old style tube amps the improvement with an electronic crossover is dramatic. With modern solid state amps the improvement is less, being related only to avoiding the problems of the passive crossover.
Suit-me with all due respect my wording in my post good have been more clear. I have limited knowlege when it comes to X-over but I am open to learning. I realize there are some speakers that would be diffacult to go active with and could be far to much trouble in the end. But I would think that a good many it would benifit if done properly which at times can be a tiresome task but worth it. The speakers you gave examples of are fine speakers indeed but you didn't give an example of a speaker that you heard in passive and then active and that was my question. I have heard 3 in active but only 1 did i hear it in both modes and that was Magenpan MG IIIa which are very simular to mine and is the reason why I am going to active it has made a very noticeable differance in my friends system. He used to have a set of Dal. DQ 10 in active and as a 5 way speaker I would think not easy to set up as he set it up as a 4 way and sounded pretty good as I used to own a pair of stock ones. I am some what Dollar challenged because of a disability and have a fixed income. Most of my system is older used but desent gear and I am just looking to get the best out of what I have. As I have extra gear (don't we all)my only needed gear was a X-over.For now the ribbon will be kept on passive but upgraded. I will upgrsde my amps when funds allow (tube or class A ss)for the top. But back to the thread as someone else said you don't see x-overs for sale often becuase people just don't part with them. I've been looking for a while for a desent one i could afford. I found the Marchand XM 44 up here in Canada for $ 400.US. I seen your thread on AA resently about going active with a sub. Interesting read, Thanks for your thoughts. benie
>But I would think that a good many it would benifit if done properly which at times can be a tiresome task but worth it. The speakers you gave examples of are fine speakers indeed but you didn't give an example of a speaker that you heard in passive and then active and that was my question
I have heard the Innersounds (and others) with active crossovers which sounded great, although I didn't hear the same speakers passively crossed over. So I cannot answer your question. But I do not wish to hear Vandie 2Ce Sigs actively crossed over, for example, because I don't think it would make sense.
I did not say that active crossovers don't have advantages, if I remember earlier posts of mine correctly without re-reading. I said they are not more popular because active crossovers can be all wrong for a given design or for a given price point. (My opinion would be different for active crossovers used for subs, because passive crossovers are much harder to implement well at low frequencies for a lot of reasons, and there's no baffle step compensation at 50 hz, and so on.)
This is why I asked what speakers you heard in both modes. Enjoy your Maggies!
Less Is More! but i want a berhinger digital crossover for my speaker/sub projects. Although once i find the right "parameters", i'll take out the digital box and replace with a cap/resistor.