Why HiFi manufacturers don't make active crossovers anymore?

Hello to all,

On the recent days, I noticed that a lot of manufacturers of Hifi 2 channel systems, had plenty of options in a not so long past, of active crossovers, like Luxman, Accuphase, higher end Sony stuff, and many more, why do you think HiFi manufacturers abandoned the inclusion of active cross overs, channel dividers, in their lineup?

Accuphase still makes a digital one.

Appears that this devices are only still relevant in the Pro Audio world, why Home HifI abandoned the active cross over route? It's correct to assume that?

I think that can be very interesting tri-amp a three way loudspeakers with active cross overs, would like to know more about it too...

Share your thoughts about the subject, experiences in bi-amp and tri-amp with active crossovers and etc....

C29d0c0c 8a4a 4032 a11f eb6239f72433cosmicjazz
You absolutely need to start doing and stop thinking. 

Grab a minidsp and a pair of stereo amps and see if you can make a working stereo pair.
What about Linn? Also appears that some multi channel amps from they have active crossover cards built in? never saw stuff like this...

Also Check out Pass Labs Discrete Electronic Crossover XVR-1

and Exposure Hi Fi  VXN crossover  


The FirstWatt B4 is 2-way. I have one in my system
The First Watt B4 is 3 way or only 2 way?
Bryston still lists a crossover on their website.

Only HiFi manufacturers that are producing active analog crossovers now are Pass Labs , First Watt and Accuphase?

Would like to know more brands, when you looking inside of some Behringer, DBX and etc.. they all looks cheap..

Good point, and one that's often lost on the "need to upgrade" crowd. If it sounds good to you, nothing else really matters. As a design focused engineer, I just love trying new things that pushes the edge of what's technically possible, just for the sake of trying it out "to see" if it sounds any better. It may sound no better than a "good" system from 5 years ago.
quizzio those Hypex amps have a great rep with the Klipsch DIY crowd. I have never heard one though.

  I note the article also says the Crowns are pretty darned good and a great deal and the only caution of note was to stay away from demand levels that could cause clipping. I might try a Hypex one day but there will be no hurry to do so since the Crowns I have are dead silent and the bigger problem I have with good output is the music files which Audacity can fix. If Audacity can't then they get trashed.
"I think the ideal way to do active would be using the built in DSP and crossover function built into server software like JRiver.
It would require multiple or multi channel DAC, but it seems the least destructive method since no additional DA or AD conversions would be needed. "

I have your solution right here:
     Source: MiniDSP SHD Studio w/ Dirac Live. Everything is received and crossed-over between up to 4 channels in the digital domain; so you can set a subwoofer crossover and split 2 channels to your main speakers above that crossover and the other 2 channels to 2 subs. Output stays in the digital domain via 2 digital AES3 output (2 channels per output)
     Digital Active Speakers: Dynaudio Core 59 Speakers receive the digital direct feed from the MiniDSP via AES3 and then runs it through their internal DSP to apply its digital crossover for its 3 drivers (tweeter, mid, woofer). 

With this system, all digital signal stays in the digital domain throughout the chain without ever being converted to analog until the very last step (speaker has internal DAC for final conversion to internal amplifiers). Why did I suggest MiniDSP as the source? You can totally manipulate the signal by either applying Dirac Live or your own REW curve to your liking so that you can manipulate the frequency curve of your favorite system to make it "warm" or "forward" or whatever you want.

As long as your source can output to AES3, the Core 59 will receive the digital signal and run that signal through their 100% digital crossover DSP. Pro gear is pretty cool.

@ mahlman  
"I am a Crown guy too. Went the consumer route for a while and tried all that "painless one touch" room correction junk and never was satisfied. You just can't beat the price and clean output of pro amps with consumer gear. "

The Crown is a "pro" amp but definitely does not "clean output" per the audio science review's measurements  https://www.audiosciencereview.com/forum/index.php?threads/review-and-measurements-of-crown-xls-1502-amp.6062/

As you can see, this pro amp is more appropriate for "live" situations where noise, resolution and frequency range is not important.
Great discussion!! You guys sent me looking through some of my older gear and i dug up a Pioneer Series 20 D 23 4 way crossover I bought years ago. My thinking then was to construct a speaker system using Kenwood LO-7M amps for the subs and 3 other tube amps for the remainder of the drivers. The tube amp I had in mind for the top end was one of those small Cary triodes that I had read glowing reports of. I still don't have one, but I have everything else except the drivers. This, or something similar to this is where I interpreted @cosmicjazz was headed with his 6 channel amp. With an approach like this it frees you up from all of the constraints of conventional speaker design. I could be all wet with that statement, and am looking for some feedback from Erik and everyone else.
If you had a sweet stereo tube amp to drive a pair of drivers for the mid- highs, another for the mids, and another for the top ends, what drivers would you choose? And something within reason....no $1000 drivers or horns need apply, just bought off the shelf stuff that you think sounds great! And a lot of this is inspired by the Linkowitz designs.
Would like to know more active analog crossovers similar to this ones, in specs, and layout functionality, anyone have more recommendations?

No DSP please.

Fostex EN-3000


Pictures: https://www.hifido.co.jp/sold/17-11127-51780-00.html?LNG=E


Model Channel divider
Specifications 2-3way electronic dividing network
Bandpass characteristic 18dB / oct
Input impedance 47kΩ
Input sensitivity 0.5V (rated output)
Rated output 1V (Low: 100Hz, Mid: 1kHz, High: 10kHz)
Maximum output 8V (+ 18dB / dBV, distortion 0.05% or less)
Output impedance 470Ω
Total harmonic distortion 0.005% or less (rated output)
Crossover frequency 2way-1: 500, 650, 800, 1.2kHz
2way-2: 2k, 3k, 5k, 8kHz
3way: 500, 650, 800, 1.2kHz (Low / Mid)
2k, 3k, 5k, 8kHz (Mid / High)
Output phase switching 0 °, 180 ° (Low, Mid, High)
S / N 100dB or more (IHF-A)
Input / output terminal RCA pin terminal (pure gold plating)
Power supply AC100V
Power consumption 4.3W
Dimensions Width 482x Height 44x Depth 235mm (19 "/ 1U Standard Rack Mount Size)
Weight 3.5kg

Fostex EN-3020 

Pictures and specs:


Manual available here:


I think the ideal way to do active would be using the built in DSP and crossover function built into server software like JRiver.

It would require multiple or multi channel DAC, but it seems the least destructive method since no additional DA or AD conversions would be needed.

Has anyone experimented with this method?

I have dreamed of modding my TAD CR1's to work with an active crossover,  but I would not want to risk damaging such an exotic driver.

The other issue is I would want not to use amps of a lesser quality than my BHK 300's (with their tube input stage) and could not afford another 2 or 4 channels of BHK.  I have read about people trading their Pass amps for BHK 300's (perhaps because of the tubes)   Maybe a pair or 3 of the stereo BHK 250 would work.  They are doing a more powerful version, unfortunately not a lower power version for multi ways which would be ideal.  

I would like to know more analog crossovers similar to this models from Fostex, EN3000 and EN3020, EN3000 appears regularly to sell in Japan, the more sophisticated one EN3020 it's much more hard to find...

Anyway, would like to know more units with similar characteristics like this ones, very straight forward 3 way, easy to use.

For those who not know this Fostex, here they are:

EN3000: https://www.hifido.co.jp/sold/14-84210-27250-00.html
EN3020: https://www.hifido.co.jp/sold/11-62786-28291-00.html?LNG=E


No DSP's recommendations please.
Not true I’m afraid - it will be impossible for any passive crossover or indeed driver to be absolutely time and phase coherent across every frequency. Some of the high end digital algorithms do achieve that.

I have experience of ’correcting’ Shahinians, JBLs, B&Ws & Royds and in every case the change was very apparent & positive.

Some months ago I also did a ’quick & dirty’ crossover and speaker calibration to some Mission floorstanders for another forum member (prior to him using MiniDSP). We were both shocked by the huge uplift in coherence, smoothness, imaging and overall clarity achieved vs the original uncorrected and passive crossovers.

I’m not trying to be controversial so apologies it that appears too blunt.
Sure DSP can correct issues and if your system has them then it is very useful. If your loudspeakers of proper design a DSP will have nothing to correct. 
Similar to member chosenplay earlier in this thread, I am also using DEQX & Open Baffle speakers ’though in my case two processors. (HDP-5 - 3-way OBs as master & HDP-3 slave with two subs).

I am 62 y old, a vinyl listener since mid 70s & was extremely cynical about using DSP with an analogue source until I actually heard it in someone else’s system!

I then researched & auditioned/trialled numerous variations including Dirac, Mini DSP, Behringer, Acourate, even Linn Exakt in recent years but for me. DEQX provides by far the most satisfying results in spite of high cost.

The first time I set a correctly time and phase aligned crossover with corrected, time coherent speakers I literally swore out loud at the clarity, transparency, cleanness and sheer musicality of what I was listening to (this was with Shaninian Obelisks & a M&K sub that I had owned for years and knew the sound profile inside-out).

The phrase ’game changer didn’t come remotely close! (that was seven years ago & I progressed a long way since then with a setup that since early 2017 is as near ’perfect’ as I could want).

Any shortcomings that may (or must?) be present in terms of transparency are buried so deep in what I hear that the positives about absolute time/phase coherence (at EVERY frequency in the case of DEQX) completely overrule the negatives I never really appreciated in most purely passive setups that I had owned or listened to.

Any sceptics reading this - please keep an open mind before passing judgement until you hear a properly configured DSP setup
To make modern active one must use DSP and chips no small manufacturers can make chips so they must rely on what's available so basically you have a few versions of basically the same thing and its why smaller companies are avoiding for now. Passive actives are kind of like a model T Ford today still they have a subjective performance advantage if done right over DSP. DSP's great strength is making the wrong work correction is what DSP is mostly about for if the design was proper most of DSP uses are nulled. 
even Marantz offered a active crossover in the early 80's... amazing: 

wish the mass HiFi brands return to produce such amazing lineup of products, how Pioneer, Sony, Marantz, JVC, Denon, made it.. 

Unfortunately that's not gonna happen hehehe
While the First Watt B4 I mentioned on Page 1 doesn't have all the controls and versatility of the Pass x/o, it has a lot more than the Bryston and Marchand. 1st/2nd/3rd/4th-order filters in 25Hz increments from 25Hz to 3200Hz. All discrete---no opamps or ic's. Level control on either the high- or low-pass filter (user-selectable), for balance matching between two amps with differing gain structures. Nice little piece at an affordable price ($1500 retail when in production, though discounted at Reno Hi-Fi). 
Sorry, but my doubt is not considering a active crossover situation... I forgot to tell that the application that I described, is considering speakers with passive crossovers...

Anyway, I think I already found the answer, the M-73 is not a 4 channel amp, it’s a stereo amp, I was thinking that was a 4 channel amp because of the looks of the amps boards inside, it was appearing for me 4 independent amp blocks, and was thinking that each of the 4 speaker’s terminals was connected into each block...

So in fact, if use the M-73 to amplify 4 speaker’s drivers (left and right horns and tweeters), it can be done, just connect each driver to the respective speaker’s terminals, and activate on front panel A + B speakers together, but it will be bi-wiring, not bi-amping.

1 -

If you put a high pass (HP) filter in front of an amp, it no longer has to play bass.
Bass is responsible for most of the amplitude variations in a signal.Amplifiers are all voltage limited. That is, they can play up to +- n V
Say n is 20 Volts. If bass takes 15 V, then you only have 5 V left for mid and treble.

Put a HP filter in front of it and now the entire voltage +- 20 V is available for mids and treble.

2 -

Most multiway speakers have resistors in front of the mid and/or tweeter driver to keep the levels similar.

These resistors waste power as heat. A necessary evil in passive crossovers.

Put an active crossover, and amp with adjustable levels and the resistors have no use anymore. No power wasted as heat = higher efficiency
sorry I don't understood sir...
Hey Cosmic,

You are right. That design stinks. He's using multiple amps, but lacks active crossovers.

He's missing a number of benefits going fully active:

- Limited voltage swing to each amp, increasing dynamic of the entire system

- Enhanced efficiency due to removal of any built in padding.

Adding 1 more stereo amp, and going to fully active DSP crossover would simplify things a great deal.

Hey guys, please, appreciate if someone can solve a doubt of mine, when considering this amp: http://www.audioscope.net/pioneer-m73-class-power-amplifier-p-1759.html in a multi amplification situation.


Here's the situation:


Considering a pair of 3 way loudspeakers, 12" woofer + radial horn + super horn tweeter, it's possible to amplify the 2 radial horns + 2 super horn tweeters, with just one Pioneer M-73?


I'm asking because I see 4 A + B speakers terminals on the back, and on the front, I see that is possible to select the A + B speakers at the same time...


It's possible? or I'm interpreting this wrongly?


Many thanks! Best regards.

I used to use GR Research OB 7 speakers which were ideal for 45 SET's which I rigged as active crossovers for the midrange and tweeter, capacitors and resistors between the 6SN7 mu-follower drivers of the 45's and an 833A driven by a 45 for the woofer. There were still peaks in frequency response which required filters in the speaker elements and these had to be passive. It all sounded very good, but just for the hell of it I tried running the speakers with all three drivers on the 833-A and it sounded much more coherent and full-bodied. Eventually I went to Mangepan 0.7's and they are a better match for SET if the triode is powerful enough for their low sensitivity. In theory active should sound better but for this it did not.
I learned another lesson. While transformer coupling is ideal for letting a 45 drive an 833-A, transformer coupling should sound better than RC coupling for the output of my preamp, but AB testing revealed to me RC coupling sounds far superior. Finally, I had a ladder step volume control which selected pairs of the finest metal film resistors and an Alps plastic volume control, which is cheaper and has less status, sounds far better.
You have to experiment and test for yourself. Fortunately, if you can afford to buy something someone else designed and tested you don't have to spend years experimenting till you are satisfied with what you choose.
Amazed how this thread grows..

Guys, I was checking some speakers projects on the web, builders that share their systems, found a interesting website focused on that, check this out:


When I look at this particular project, this makes me think, wouldn’t be much more straight solution, if that guy opted in go active?

I think go active isn’t all necessary a complicated solution, in fact, can be much more straight forward..

I think this system must sound very very nice, but I don’t think If I dig all the mess of all this amps going trough the DIY passive crossover that the guy designed for it...

What do you guys this?

An active solution wouldn’t be a much more elegant way to cross and tuning the frequencies response on this huge 5 way speakers?

Actual speaker crossovers are complicated.

If you are going to replace a speaker's internal crossover with an external you are going to have replicate the entire transfer function, not just the crossover location and slopes. DSP makes this a lot easier to accomplish.

If on the other hand you are just adding a sub to the bottom end, an analog crossover can do what you need.
I disagree that analog crossovers inherently sound better. You can make more complicated slopes that address issues with the room that no analog crossover can touch. You can time align the speakers from the listening position which alone is a huge benefit to imaging. When the filters operate at 24/96 or higher there is no loss of fidelity. While some users make fun of people being intimidated, it’s like anything, that once you know how to do it of course it’s easy. Leveraging the power of Room EQ Wizard and Multi Sub Optimizer to build filters that make the best sound in a room has an initial steep learning curve but the payoff is amazing. I’m happy to talk anyone through it as it took me a great deal of reading and trial and error to get everything to work. 
By the way, digital crossovers are easy to use but analog one will give you better sound. I had dbx Driverack but was not satisfied with sound. I have used Krell and Apogee, but Marchand has been my most rewarding so far.
I have been using Marchand Electronics crossover for 2+ years and have been very happy. Phil Marchand is a very knowledgeable person and can guide you to what you want. Part quality is superb, price is very reasonable, crossover modules are very reasonably priced and you can experiment with slopes, crossover points, single ended or balanced etc. without breaking your bank. Pass crossover uses least used and difficult design whereas, Marchand uses Linkwitz Riley, has no phase problems. My speakers are 4 way and tried about 4-5 different crossover points, liked the present one and have stayed with it. Not a difficult job for someone that is not an engineer. Sound is much better than passive crossover, more dynamic.

Very interesting thread. I'm relatively electronics-ignorant compared to many here--but still have a story to tell.

I'm a longtime audiophile who, for reasons too complex to outline here, has been confined to desktop audio in home office for ~20 yrs.
For a long time I used a modest 2.1 active system in my home office: 2 X NHT Pro M-00 satellites + S-00 sub. The output of my preamp du jour went to RCA input of the sub; and the RCA outputs (shorn of frequencies <100 Hz, went to the satellites. I tried this same sub w/other active satellites and it always sounded good. 

Then I upgraded to an SVS SB-1000 sub, which also has a filtered output (big reason that I selected it). Using the same wiring as before, I became aware that the sound from my satellites (which eventually morphed to passive monitors driven by a big class D amp) didn't sound quite right. My current monitors, ATC SCM12 Pro, ran straight from amp/no sub for awhile and so I know how these very resolving monitors should sound. But driven by the output of the SB-1000, not so good.

I picked up a gently used Marchand XM66 variable 2-way crossover w/24 dB slopes. Installed that (everything got more complicated), but immediately heard that exact same ATC sound that had been compromised off the output of the SB-1000. So consider this an electronic crossover success story.

EXCEPT...upon installing the XM66, I've had a ground loop ever since. Have tried almost everything to eradicate it. I think it's the crossover, which basically connects to most of the power supplies on my complicated desktop. 

(no perfect world)
Sorry, but I can't help but chuckle at the image of all these "audiophiles" wringing their hands over active crossovers being digital and too complicated, modern DSP crossovers do it all quick, clean and efficiently no matter what configuration you are trying, Bi, Tri, 2.1. Trust me, you won't hear any degradation from this unit and any bi-amp or tri-amp system will sing like never before. 
I was introduced to active crossovers (pre-digital) while working as a soundman for clubs and bands back in the early 90's and it allowed me to get the most out of whatever I had in the way of speakers and amps, which BTW is usually all run in mono. I took home a basic 2/3 way stereo X-over and started playing with it and was able to get some remarkable results with a little fine tuning. B/K Sonata 5ch amp worked great. Clarity and power like crazy, and solid thump out of subs instead of boom.
Today's technology makes it easy precise if you can get over your digi-fear.
The best crossover is a high grade capacitor to roll off the bass going into the mid/high.

If you are going to go with multiple amps, or a satellite/sub, this is a really good compromise. No more parts, or power supplies, at the expense of only having a 6 db/octave rolloff.

If you use sealed (or plugged ported) speakers you can increase your speaker's dynamic range, improve your power handling somewhat as well.
I have a Luxman integrated that lets me separate the pre from the main amp and I'm thinking about doing exactly this.


I use the 2x8 mini DSP. All filters are run at 24x96 and I have everything connected via balanced connections. The computer interface is simple and intuitive. Basic slopes are easy to create and load. On the 2x8 I added a selector knob which offers multiple options for source and many configurations for each source based on what you are listening to. For example I have a 5db increase on the subs for movies. Having the extra oomph is fun, makes friends jump out of their seats :) I also got the add on for SPDIF inputs which is lossless and seamless from my Mac Mini. 

I bought the board and case separately that they offer. It’s a very high quality piece of equipment. The flexibility is impressive.

The 2x4 only offers RCA connections and runs at 24x48. Depending on your application and size limitations I would spend a little more and go with the 2x8 option.
The best crossover is a high grade capacitor to roll off the bass going into the mid/high.

One of my systems uses a pair of monoblocs to feed the mid and highs, and a separate set of monoblocs to feed the bass, with what is basically a fancy gain control in that end of things to allow matching of the outputs of the two different amps.

But not everyone wants to pay for two (or three or four) power amps instead of one and all the extra speaker cables (mine are triwired).

When you get into active crossovers you've added another electronic unit to the line that may or may not affect sound.
I agree whole heartedly that you can acquire a much better synergy of components by utilizing an active crossover!  Being a DIYer myself, my system is composed almost entirely of diy components and it sounds absolutely fabulous!  

My active crossover is a Sublime audio K231.  It is completely customizable and they are a great company to deal with.  Don't let the $500 price tag fool you, this is a top quality component!  

Would be happy to answer any questions in a PM, but don't want to get into the back and forth on this website!

I have used active electronic crossovers for the last 30 years on my Magneplanars, first on my MG2's and later on my 3's, and now on my MG20.1's. I used the Bryston 10b and 10b sub to drive my system in the triamped mode for the last several years on my MG20 + subwoofers system. Two years ago I replaced my Bryston 10b's with 2 of the Pass Labs XVR1 crossovers to run my MG20,s and subwoofers. Today after a year of trial and error listening I have settled on settings that are very satisfying. I ended up using crossover points and slopes that were close to, but not the same as the settings Magneplanar recommended as a starting point. The Pass Labs crossovers are very complex, but they also allow extremely accurate settings for the crossovers. The Pass XVR1s can set the crossover frequencies, slopes, high pass and low pass frequencies, Q factor at the crossover, and also allow independent settings for volume on all crossover sections. Pass Labs created these crossovers to use in testing their equipment during the engineering process.

I knew that I could use the manufacturers crossover setting recommendations to begin with so a lot of trial and error was eliminated this way. Some things I learned along the way, at least on my system: 6db/octave crossover slopes sound best. The Q factor settings did not affect the 6db/octave crossover slopes, per the included manual for the crossovers. The sound was better (in my system) with the MG20's and subwoofers running in parallel, not in series. i.e. the bass panel of the MG20's is not cut off on it's low frequencies, but allowed to run down to its natural cutoff. The subs and main speakers sounded best with the highest slope setting in the sub crossovers, 24 db/octave. Low frequency cutoff on the subwoofers was 48Hz, which eliminated a room mode at 60hz in my system. I found that using low frequency settings on the subwoofers sounded best with steep slopes.
I think that Pass Labs website has an electronic copy of their XVR1 crossover manual. This does a very good job of explaining the multitude of settings available on the XVR1 crossovers. I Highly recommend downloading and reading this for a reference manual for anyone contemplating Bi or Tri amping their speakers. The Pass Labs XVR1 crossovers have over 1 million crosssover setting combinations, so the process is daunting, especially if you don't have a starting point in the beginning.
As a suggestion: Use the lowest frequency you can for your subwoofer low pass setting that allows the subs to "fill in" the main speakers low end response. The subs will sound best with steep cutoffs like 24db/octave. 6db/octave slopes sound best on the main speakers, and give the best phase response for the speaker's cutoff sections. Calculate your room resonance modes (based on the LxWxH dimensions) and avoid sub settings that will excite these modes. The room resonance modes are the cause of "boominess" in your sound room. For example, my room is 18 feet wide and the room mode for the width was approx. 60Hz. I first used a sub crossover frequency of 60hz, and struggled to reduce the "boom in the room" until I lowered the sub crossover to 48hz. This lowered the sub output enough at 60 Hz to eliminate their contribution to that mode. Then I was able to move the main speakers around to minimize their contribution to the boom.
FYI - I still own the Bryston 10b and 10b sub crossovers and would like to sell them to another person wanting to biamp or triamp their system. I don't use them now, and it is a shame to leave them unused on the shelf. These crossovers analog, not digital, and are excellent sounding, and easier to set up than the Pass Labs XVR1's are. The Pass XVR1 do sound better, though.
This post is long, but I hope helpful to you in the use of electronic crossovers in your system.
hifidream what MiniDSP are you using? I am thinking about making some two way systems and providing some sort of preprogramed DSP with them. At $200 the MiniDSP 2x4 price is certainly right for doing this. What is the quality of the output?
I've used both fully active biamped (Snell Type A II Imp), passive biamped (Martin Logan Prodigy, with level adjustment for woofers), and regular passive systems.  In reality, every system with a subwoofer is a passive biamped system.
In general, if you have the ability to do the setup, I think a full active system will be superior. I knew a guy in the 80s with a full Levinson HQD setup: 3 way active biamp setup of Hartley woofers, stacked quads, Decca ribbon tweeters, 6 ML2 amps, 2 LNC2 xovers, 2 ML6 mono preamps. He was very capable and the sound was excellent.
That said, I will always observe the speaker maker's recommendations for slopes and use an RTA with pink noise for initial setup, tweaking afterwards for taste.
One aesthetic issue is the quality of the crossover.  Would you want to put in line, between the exotic amps and preamp, a $200 cheapo xover? Probably not.
The new DSP based xover systems, assuming excellent DACs, would be a great solution. You'll need a speaker system with access to the driver terminals and the ability to eliminate the passive elements from the signal path. The DEQx, while limited to PCM at 96K output, has SPDIF digital outs for each of the 3 xover output bands.  This means you can create as elaborate a digital system as you like: Streamer->DEQx->3 MSB select->6 MSB mono amps. Wow!
The two most important considerations for a stereo are your speakers and the room that they are in. Passive set ups don’t allow you to dial in the speaker room interaction like active crossovers do. That’s the real advantage in my opinion. I use REW with a high end microphone to analyze the room. I’m able to add 12 biquad filters to each channel with my mini DSP. The distortion tamed by this process is unbelievable and the sound improvements truly amazing. Most consumers don’t want to mess with the process but it only requires probably a day of messing around and then it’s set which people argue is a Sisyphean task and never ending. You need to add multiple amps as people have noted and have multiple subs to really make an active set up effective as most distortion and negative room interactions happen at lower octaves. 
I purchsed an ART 355 EQ whicj has high ratings. I have read people ising this on systems much more expensive than mine.  I was totally dissatisfied with what it did on my system.
1  compressed the sound no matter how it was adjusted
2. Soundstage disappeared.
It was not good.  
The only one I ever owned that did it all righr was an audio control c101.  
miniDSP has some nice active crossovers for different price ranges, just found them in the last week. 

I also have good experience with custom made Linkwith crossovers via aliexpress. You can choose the frequency and upgrade the operating amps. I took Muse8900 this time, but before even the Muse02 from italy. Quality was really good to be honest! I have put it before two Nap200 going to B&W PM2. For this speakers clarity increased and I could play louder in biamping. 

For my Elac507 Biamping didnt work! I think the reason is that the impedance of Low and High is different themself. In Biamping mode i had far too much bass. First i didnt like the speaker. When stopped biamping te sound became a dream. So i am out of biamping :) just got a Primare A32 with 2x400 Watts at 4Ohm and all is perfect. The only thing I will do is to go on wi-wire for the High-channel. I tried that once with Kimber 4TC and the effect was nice for the mid and high range, but it was not my cable. 
"Midrange compression driver in the Uccello’s is the B&C DCM50, and the tweeter is the DE10 - also from B&C. The midrange horn is a "variation" of or slightly modified version of the Eliptrac 400 (the modification, to my knowledge, seems to entail the edge of the mouth of the horn, and how it meets the baffle here) and yes, it’s made of CNC’d, stacked birch plywood.

What’s the details of the bass horn you’re using with the 402 mids horn - does it sport a 15" driver, and how low is it tuned? Any thoughts on the 2" (exit) driver to use?"
  That DE10 is a super driver and the one I use on the MAHL tweeters I make. The bass horn uses the Klipsch K-43 woofer and is -10DB at 27hz and near full output as low as 31 DB.
  The 2" driver on the 402 is a Klipsch 1132. I am going to experiment with some 2" throat horns soon and thinking of B&C for those to since I am an OEM with them.
  The Crowns are nothing fancy and are xli800's.    A Xilica xp3060 is the brain behind it all.
Hey phusis that is a nice looking setup and I have heard good things about the lilmikes.

Thanks, mahlman. Lilmike has made some great subs. Initially I considered a pair of the Cinema F20 FLH’s, but wound up being invested in the characteristics of tapped horns instead, also thinking about building the LilWrecker TH’s which are tuned some 5Hz lower than my MicroWrecker’s. There’s no free lunch, though, as they say; a 5Hz lower tune in this case eats up about 5dB’s of sensitivity, further limits the usable upper bandwidth, and turns them into 30 cubic feet or 850 liter monsters (the MW’s are 20 cubic feet per cab - not small by any stretch of the imagination). I also considered Josh Ricci’s Gjallarhorn tapped horns fitted with an 18" driver, but they’re huge, and the driver they’re build around, the TC Sounds LMS Ultra 5400 (weighing in at a ludicrous 80lbs) can no longer be had. Lastly I very strongly considered Ricci’s Othorn, fitted with a B&C 21" driver (the 21SW152 - a beast) and indeed the runners-up to my MW’s, but budgetary constraints mainly had me favor the MW’s.

What drivers are you using on the top section? I have a rebuild LSI bass bin I am thinking of making into a two way with a 2" compression driver for 500hz to 18khz . Are those Fastrac horns and were they made from stacked Baltic Birch? I have a CNC mill and I an thinking of making some mid horns too.

Midrange compression driver in the Uccello’s is the B&C DCM50, and the tweeter is the DE10 - also from B&C. The midrange horn is a "variation" of or slightly modified version of the Eliptrac 400 (the modification, to my knowledge, seems to entail the edge of the mouth of the horn, and how it meets the baffle here) and yes, it’s made of CNC’d, stacked birch plywood.

What’s the details of the bass horn you’re using with the 402 mids horn - does it sport a 15" driver, and how low is it tuned? Any thoughts on the 2" (exit) driver to use?

I am a Crown guy too. Went the consumer route for a while and tried all that "painless one touch" room correction junk and never was satisfied. You just can’t beat the price and clean output of pro amps with consumer gear.

Crown has made some extremely capable amps. Once considered buying a used Crown Studio Reference II - a lovely, very underappreciated amp that I could see go favorably up against a range of much more expensive commercial amps - and within the next month will replace my old Macro-Tech 1200 with a K2 for subs duties. What Crown are you using?
Open baffle. 15" top/bottom, 10" planar magnetic mids, amt in the center. Baffle is sandwich of 3/4" ply, 3/4" mdf, 3/4"ply. 72" by 19".
Hi @closenplay

Very interesting combination of features!!

Is it a traditional enclosure otherwise, or open baffle??

I have been enjoying an open baffle WMTMW 3-way (my design) using a DEQX HDP-4 for a few years. A great option, especially if you like to tinker. Check out their website for some features that set them apart from others. All other design variables being equal, a fully active speaker sounds (to my ears) better than the pasive version of same. Also amp rolling can be a fun journey (if a bit expensive). Ex.. use an iron fisted ss amp for the woofers, tubes for the mids, highs.....or vice versa......as you prefer the sound. Just play around, you might find some pleasant surprises.
I have a First Watt B4 (designed and built by Nelson Pass) that I will never sell. He also makes a x/o under his Pass Labs brand name, but it's a LOT more money.