Active Crossovers

[mikebse2a3]

Hey Rudy81

If it helps any here are some of what I've learned and experiences that pertain to this subject.

Time alignment is important in the fact that it allows another
variable in fine tuning the loudspeaker system's operation through the
crossover region to maintain the best amplitude, phase and controlled
polar response so that the loudspeaker system integrates with the room's acoustical
nature and listener or listeners locations in a more predictable
manner.

Stereo as we record/playback (by it's own designed limitations) truely
has only one "Sweet Spot exactly centered between the loudspeakers"
but a loudspeaker designed like the two-way Jubilee/K402 with it's
wide bandwidth controlled polars means all locations in the room are
going to receive a signal similar to the on axis signal within the
loudspeaker system's approximately 90deg. H x 50deg. V window (some HF
narowing begining around 7kHz to 8kHz the polar response is affected
more by the HF Driver's phase plug). I'm not sure many people
understand how unique the Jubilee/K402 system is in accomplishing the
above and how important this is..!

I perceive Time Alignment as used in the Jubilee/K402 as a refinement
in the reproduction to vocals and instruments that have energy in the
crossover area (approximately acoustically centered around 500Hz).
It's not a night and day difference by any means but does remove a
very slight coloration and loss in clarity in the crossover region
IMHO when they are A/B compared with material that exposes this
region.

Speaking for myself having used the EV DX38 active setup for over 3
years now I really never see myself going back to passive crossovers
from a performance standpoint as well as because of the versatility it
brings to my system and any changes I want to make.

The main point I would want to make for anyone is whether you design
with passive or active if your goal is accurate as well as excellent
sound you really need to learn to use measurements as well as
listening test to optimize your design. Also on that note active
crossovers like the EV DX38 can store many programs so it is very easy
to tweek the parameters and do A/B comparisons until your satisfied
with the results and that would be extremely hard to do with a passive
crossover.

mike tn

[Rudy81]

Mike: Very good comments on the subject. I have experienced the large enveloping sound of the Jubilee. I liked that ability of the driver and horn. In my very limited experience with the system; however, what I did not hear was precise imaging and a clear soundstage. I don't know why that was, but my Khorn setup did a better job in those areas. In fact, I was so distracted by the lack of imaging, that I ended up not paying too much attention to the bass bin performance.

I am looking forward to using an active crossover precisely for the benefits you mention. I think I should be able to at least test the theory pretty inexpensively. I am waiting to see if I can pick up a multi-channel amp for my center and effects speakers. I then plan on using my Parasound HALO A23 and A52 to power the six drivers separately. For my taste, those amps are great with horns.

I hope I get to do this sooner rather than later.

[mikebse2a3]

Coytee: I just did some critical listening with "The Ultimate Demonstration Disk" to try and discern the issues you have talked about, in particular the lack of coherence at close distances with the Khorn. Either I don't know what I'm listening for, or it is not evident in my room. That got me to wondering where you had your Khorns. Is your room acoustically treated? Is it very live, lots of glass, things like that?

I agree with you also in that when I had Khorns in 3 different well treated rooms over time coherence due to close distance was never a problem I perceived.

I've not heard Coytee's Jubs in his room but did hear his Khorns in the same room and it is much more of a complex enviroment than a basic rectangular room would be because of the more open floor plan of his home with other rooms acoustically coupling to his room that the Khorns were in.

I started to wonder if up close you are hearing room reflections that are creating the illusion of lack of coherence. It seems to me that a relly reflective room would seem poor up close, but as you move far out, the detrimental sound effects would not be as evident. I have a relatively flat room with heavy bass treatment in all corners. Early reflection treatments, and rear wall diffusors. My room measurements helped me select the treatments and I finally have a relatively flat response. Audyssey takes it one step further and takes out the Khorn hump.

Actually when it comes to room reflections if we are using horns with well chosen and wide frequency bandwidth controlled coverage angles the room would only make things worse as we move away from the system. My opinion based on experiences to date are that I really like a lively room as long as I use diffusion like the RPG Skyline diffusers to control the early sidewall specular reflections while also creating increased lateral reflections that contibute to a diffusive sound field giving an impression of spaciousness and envelopment.

Again I would like to encourage people to read Floyde E. Toole's excellent book "Sound Reproduction Loudspeakers and Rooms" which is basically a summary of his lifetime of work in these fields.

I now beleive that the biggest advantage for me with an active crossover will be the ability to steepen the crossovers. Isolating the drivers may provide a larger improvement than 'time alignment'.

I will certainly keep after this 'experiment', if nothing else to satisfy my curiousity and to learn something new.

Again I believe time alignment is best taken advantage of when all the variables have been addressed that effect the crossover region like amplitude/frequency, phase and polar behavior of the horn/drivers being combined into a system.

This is were a Jubilee/K402 has an advantage because the K402 is especially consistant in it's controled directivity over a wide bandwidth and especially in the 500Hz acoustical crossover region being used.

mike tn

[mikebse2a3]

I have experienced the large enveloping sound of the Jubilee. I liked that ability of the driver and horn. In my very limited experience with the system; however, what I did not hear was precise imaging and a clear soundstange. I don't know why that was, but my Khorn setup did a better job in those areas. In fact, I was so distracted by the lack of imaging, that I ended up not paying too much attention to the bass bin performance.

I asure you a properly steup Jubilee/K402 installed in a room with good acoustical characteristics can deliver very precise imaging and soundstaging. In fact the Jubilee/K402 should (this is true in my case) be even better than a KHorn because especially with the K402 more of the acoustical energy is delivered in a controlled pattern and thus splashing less frequency dependent energy unevenly about the room.

As I'm sure you know one of the first things you lose is imaging and soundstaging if the room is masking those cues from the recording.

mike tn

[DrWho]

I just did a little 10 minute experiment. Perhaps others (Ben?) can chime in if I did it in a reasonable way or screwed it up.

I went downstairs, hit play on what ever was currently in player (Toto live). Killed my right channel, hit the mono button on the Peach. Even as I sat there, I merely dialed the delay on the woofer way out there. I figured let's start long & work short.

I put it the delay mode into meters so I could get away faster. Had it up to something like 500 meters lol. Talk about sounding kind of funny.

I dialed it down, back up, back down.... I'd say that Ben is absolutely right. The biggest single change that makes these thing "one voice" is simply going to a 2-way. I had the delay set on 9 meters. I could still hear a difference as I sat right in front. I went to my location 30' away and gave a listen. The scale of the "one voice" was still there but it had some echo in it. Even though it had some echo, it still sounded more similar 30' away as it did 10' away which is something I never said about the Khorns.

Thanks for giving me a mild enough kick in the pants (and the suggestion) to try something like this. If I did it totally bass ackwards, tell me how to do it better and I will.

I'm not quite sure what all settings you tried, but the best way to demonstrate the effects of time delay is to switch back and forth between mis-aligned and aligned delay. So if you want to hear what a passive with no delay compensation might sound like, then set the delay to zero and then swap back and forth between zero and the correct setting.

The instrument I usually focus in on is the snare drum in rock recordings...you want to pick something that definitely spans the xover region (so don't pick a flute for instance since only the tweeter would be reproducing it). The snare is also good because it's very transient, which brings out phase nonlinearities a lot more. With no time-alignment, the snare will sound more like a "shhhh" sound and then when time-aligned, it'll go back to more like a "tch" sound.

[DrWho]

I started to wonder if up close you are hearing room reflections that are creating the illusion of lack of coherence. It seems to me that a relly reflective room would seem poor up close, but as you move far out, the detrimental sound effects would not be as evident. I have a relatively flat room with heavy bass treatment in all corners. Early reflection treatments, and rear wall diffusors. My room measurements helped me select the treatments and I finally have a relatively flat response. Audyssey takes it one step further and takes out the Khorn hump.

For what it's worth, the same "point of coherance" happens outdoors too...

[Rudy81]

I asure you a properly steup Jubilee/K402 installed in a room with good acoustical characteristics can deliver very precise imaging and soundstaging. In fact the Jubilee/K402 should (this is true in my case) be even better than a KHorn because especially with the K402 more of the acoustical energy is delivered in a controlled pattern and thus splashing less frequency dependent energy unevenly about the room.

As I'm sure you know one of the first things you lose is imaging and soundstaging if the room is masking those cues from the recording.

mike tn

I suspect that to be true. That is why I keep hunting for a well setup system. I figure all Jubilee owners can't be wrong. The system must also offer some improvements due to the 2-way design vs. the 3-way. I think you guys need to talk Roy into having a loaner system like Greg did with his V-tracs. Maybe we can get FedEx to sponsor the thing and provide free shipping???? [6]

[Rudy81]

For what it's worth, the same "point of coherance" happens outdoors too...

Well, if that is the case, then I don't know what to listen for. In this case, ignorance may be bliss, otherwise I'd be going nuts trying to fix the 'problem'.

[ClaudeJ1]

I had been totally unaware of the 'hump' in the Khorn until I started measuring frequency response in my room. My system shows a hump right around the 200-300 Hz band. I found, totally by accident, that it is what gives the Khorn a bit of a 'tubby' sound. I can easily turn that on and off now and the difference is clearly obvious. I started using Audyssey to tame minor room influences, and that hump was cleaned up by Audyssey.

Yes, and in the same manner, there's a hump in the LaScala at about 150 Hz. as well as in the Peavey SP-1/FH-1 bottom, which is like a slightly larger LaScala bass with a more solid construction.

Even the published curves on EV/JBL horn/driver combos show a midband peak with a gradual taper at both ends before their respective high and low rolloff. This is why having modern active PEQ, whether it's "PEQ for dummies" like the built-in Audyssey in midrange 5.1/7.1 receivers or with Pro Level Gear like the Behringer 2496/ EV DX-38, etc. it's a HUGE benefit to take advantage of that technology in taming one of the few anomalies of horns.

[ClaudeJ1]

Hey Rudy81

If it helps any here are some of what I've learned and experiences that pertain to this subject.

Time alignment is important in the fact that it allows another
variable in fine tuning the loudspeaker system's operation through the
crossover region to maintain the best amplitude, phase and controlled
polar response so that the loudspeaker system integrates with the room's acoustical
nature and listener or listeners locations in a more predictable
manner.

Stereo as we record/playback (by it's own designed limitations) truely
has only one "Sweet Spot exactly centered between the loudspeakers"
but a loudspeaker designed like the two-way Jubilee/K402 with it's
wide bandwidth controlled polars means all locations in the room are
going to receive a signal similar to the on axis signal within the
loudspeaker system's approximately 90deg. H x 50deg. V window (some HF
narowing begining around 7kHz to 8kHz the polar response is affected
more by the HF Driver's phase plug). I'm not sure many people
understand how unique the Jubilee/K402 system is in accomplishing the
above and how important this is..!

I perceive Time Alignment as used in the Jubilee/K402 as a refinement
in the reproduction to vocals and instruments that have energy in the
crossover area (approximately acoustically centered around 500Hz).
It's not a night and day difference by any means but does remove a
very slight coloration and loss in clarity in the crossover region
IMHO when they are A/B compared with material that exposes this
region.

Speaking for myself having used the EV DX38 active setup for over 3
years now I really never see myself going back to passive crossovers
from a performance standpoint as well as because of the versatility it
brings to my system and any changes I want to make.

The main point I would want to make for anyone is whether you design
with passive or active if your goal is accurate as well as excellent
sound you really need to learn to use measurements as well as
listening test to optimize your design. Also on that note active
crossovers like the EV DX38 can store many programs so it is very easy
to tweek the parameters and do A/B comparisons until your satisfied
with the results and that would be extremely hard to do with a passive
crossover.

mike tn

Amen, brother Mike. It take an incredible amount of time and work to tweak up a system, such as what you have done, along with adding some aesthetic qualities in the process. Hats off to you for having the time and money to take that approach.

Like the Middle English author (Beowulf) Jeffrey Chaucer once quoted someone who was a craftsman of some sort: "The life so short, the craft so long to learn."

[ClaudeJ1]

I hope I get to do this sooner rather than later.

The $300 Behringer DCX2496 is a cheap way to try all this. Plus there's a whole forum on Yahoo as to how to mod the thing for pristine sound, if you so choose. Add an additional $150 for XLR to RCA cabling and you are ready to play with curves, Xover points, PEQ's, gains, etc. to your heart's content.

Ask Dr. Who about a cheap test rig and you will have enough measurment capability to amaze your friends. LOL.

[Rudy81]

The $300 Behringer DCX2496 is a cheap way to try all this. Plus there's a whole forum on Yahoo as to how to mod the thing for pristine sound, if you so choose. Add an additional $150 for XLR to RCA cabling and you are ready to play with curves, Xover points, PEQ's, gains, etc. to your heart's content.

First, several members have volunteered to lend me their DX38s, it doesn't get cheaper than that. I have also been looking at the new EV DC-ONE which is perfect for a 3-way system, with XLR and all the bells and whistles. New it can be had for the $890 range and used is down around $600. Not bad really. No tinkering required!

Once I know something is worth the money, I don't mind spending the bucks to get it. I have learned, however, that not all changes are worth the cost and I end up collecting a bunch of electronics I never use.

[mikebse2a3]

Rudy81

From your post and descriptions it sounds to me like you are experiencing Klipschorns in a way not many people get to experience them. I get the impresssion from reading the forum for many years now that very few people have actually heard Klipschorns(I'm speaking stock form) provide excellent imaging and soundstage that they are fully capable of when provided with good room acoustics that works with our ear/brain requirements to pull off this illusion.

Well integrated Klipschorns/rooms when reproducing recordings capable of good imaging and soundstage can make the wall behind them appear to open up onto a soundstage with excellent depth and where one can hear the sidewall and backwall reflections (captured/or created in some instances) of that space with lifesize vocalist and instruments arrayed in this space. One observation that also will be made when this capability exist is that often the Klipschorns will appear as if silent and not directly the source of the sound's reproduction (unless of course the position of the reproduced sound is located at the speakers position) and instead again everything being reproduced has it's own location across the sounstage with differences in depth location as well.

Some interesting experiences I had 20 years ago was at the dealer for Klipsch in my area. They were like alot of dealers were their demo rooms was often changing due to the amount of loudspeakers they would have in the room and were the loudspeakers were located in the room being shifted around from time to time. What I experienced over time was that a person could walk in and hear imaging/soundstaging just liked I described above or on another visit only hear a vague and confused image/soundstage. What I began to notice was if the room was fairly empty of loudspeakers the imaging/soundstaging was generally at it's worst but as they would begin to stock up (for the increased selling periods) the room would disappear and the wonderfull imaging and soundstage would be there again. What was causing this shift in capability? The Klipschorns were the same, the room size was the same but the way the Klipschorns and room integrated was different. What we had was a condition were I believe as more loudspeakers were introduced into this space and arrayed about the room their different bass enclosures were acting as resonators that assisted with the modal response of the room in a beneficial way and the cabinets of the loudspeakers themselves were helping to create a much better diffusive enviroment. The main thing was the cues from the recordings were no longer masked by the room allowing the listener to hear into the recording the detail, clarity, imaging and soundstaging captured at the time it was made.

If you think of this logically a person can see that the Klipschorn and Jubilee are more alike than different other than the Jubilee/K402 has a better ability to deliver it's energy in a controled manner to the room. Attention to early and discrete reflections from the room and dealing with the room's modal region issues should provide the ability to hear well defined imaging and soundstaging from either system. When loudspeakers have dispersion characteristics that vary with frequency they are more unpredictable in how and were to treat the room for reflection issues. Also likewise when rooms vary from rectangular in nature to much more complex shapes with coupling to other spaces also occuring then dealing with modal and reflections issues also becomes much more complex.

mike tn

[Bigdnfay1]

Just let me start by saying that I have never heard factory Jubs in person, so my opinion may differ from others(don't flame me to bad). Several years ago when I built my clones my intention was to go 3-way($). I had a few emails back and forth with Al about using his ES networks for my project and he said there may be issues. Not knowing all the nuiances of the Jub at that time,(keep in mind I'm no expert) I went with the ES 700/7500. Since then I have tried several woofers and mids settling on the K-31, JBL 2445H and the JBL 2404. To my ears this combo with the ALK ES sounds wonderful. After reading all the posts about active XO's I picked up an Ashly XR-1001 stereo 2-way. After getting it all jacked in and adjusted I was expecting a jaw dropping result. Now I know this unit dosen't have all the bells and whistles(EQ,time delay,etc.) that some others do but I thought it would give me an idea of the difference between active and passive. Now it could be the horn and driver I'm using(Goldwood PB-450, jbl 2445)but I didn't get the result I thought I would. Don't get wrong,they sound good(to my ears).After 2 weeks I put my passives back in and I got the sparkle back. Other options, Behringer, K-402's, better mid drivers,Jub specific passives,all cost $. For what it's worth, these have been some of my struggles to obtain nirvana.

Big D

[Rudy81]

mikebse2a3:

Well, I'm not sure of how good or bad my set up is compared to others. It is much better than it used to be before I made many changes. These are NOT stock Khorns, so it would be unfair to say that I am listening to Klipschorns as they came from the factory. I am certainly no acoustics expert and don't even know if I can objectively judge a system. I have tried to learn as much as I can about acoustics, room interaction, crossovers, drivers, horns etc. I still know very little. To summarize, here are the changes I have made over the years.

Room acoustic treatments. (IMHO, THE biggest improvement I ever made)
ALK Universal Crossovers.
Heavy Duty false corners.
ALK Trachorns.
JBL 2470 mid drivers.
Eminence APT-150 tweeters with Eminence horns.
Crites Woofers.
Audyssey room EQ.

As you can see, stock is not a word that would describe my Khorns. All these changes have been incremental and resulted from the goal of improving on an already great design. I have been looking into this driver alignment issue to try to wring out the very best my current system can provide.

I do know these Khorns produce very sharp and detailed imaging. I do know they pump out some very deep and powerful bass within the bass bin's capability. (I will say that I struggled, literally for years with lack of bass issues. It was not until I built the heavy false corners and truly sealed the bins that things changed.) The sound-stage is such that with a good recording, the speakers are not there. I cannot tell where the sound is emanating from, only the illusion of the various instrument's location is there and can be very precise. I have not heard a lack of coherence between the different drivers. Now, I do know and can measure the interaction between drivers at the crossover points....and that is not a good thing. I have measured and can graph the mid and woofer out of phase at a very particular point. I was able to reduce that issue by inverting the mid driver phase, but the drivers do compete in that frequency range.

I have moved the horns all over the room within the constraints of the home theater layout trying to find the best location. I found purely by accident that if I moved the Khorns and corners away from the front wall about two feet, but kept the Khorns up against the side walls, I got as good a sound-stage and imaging as I have ever heard in that room. I previously had the Khorns angled to 'fire' at the sweet spot. The latest improvement was in the tweeters. I previously had the Crites CT-125 tweeters mounted on the outside of the top hat after the Trachorn install. That tweeter horn was very directional and I found that the highs were rather localized with limited dispersion. Purely as an experiment I ordered the Eminence APT150. Same driver as the Crites tweeter, but a much larger horn. Wow, what a difference in the way the sound emanates and is no longer so localized. Now, this is not some world class system, but it is as good as I have owned thus far. I am dying to hear a set of well set up Jubilees in my room. But that would be an expensive experiment.

In my continuing search to improve things, I have been trying to listen to the Jubilee bass bin. I have listened two one genuine system and one clone system. Neither bass bin produced near the bass impact my Khorns produce, and no, my bass is not boosted in any way. In fact, Audyssey reduces my bass output. The one system that did impress me was the clone system I heard. Not the bass bin, but the frequencies above 150 Hz. This particular system had Jub clone bins with an Oris 150 set of horns. I don't know what drivers were being used. But, the sound was amazing from those horns with a clarity I have yet to achieve in my system.

So, I still search for improvements. Thus, my attempt at messing around with an active crossover that will allow me to steepen the crossover slope as well as play with time delay.

BTW, I was already aware of the pitfalls of auditioning a speaker in room full of other speakers. That is not a good way of judging how a speaker will sound in a room by itself. You are correct in your impression of the effects other speakers make in a room. Particularly when a large number of other speakers are present.

[mikebse2a3]

Maybe it would be good at this time to point out that it is very unlikely that anyone can just remove a passive crossover and then install an active crossover and then be able to do an apples to apples comparison. Response curves on the two systems would probably show differences that might be audible.

Remember the function of the passive or active crossover is to ultimately provide an electrical voltage/phase corrective signal to the horn/driver. The horns/drivers only cares that this is done correctly regardless of how it is acheived. The ultimate goal is the acoustical response of the loudspeaker through the crossover region provided by the electrical drive to the drivers/horns.

The reality is the actual acoustical crossover frequencies could be very different than the electrical crossover set points. To acheive the same acoustical crossover response for the loudspeaker system when doing active v passive .

In other words when you design the passive crossover you will have to take into consideration the horn/drivers electrical and acoustical characteristics to choose the proper passive componet values to hit your acoustical crossover target(text book values are unrelaible in the real world of speaker design).

The active crossover though doesn't directly interact with the varying driver impedances but it must still account for this as well as the acoustical characteristics of the horn/drivers so selecting a certain crossover frequency and slope is again no guarantee that you have hit your acoustical target crossover and in fact the active settings (as well as the Passive crossover's design and componet values) could be far from optimized until measurments and listening are used to tweek the electrical settings to hit the target acoustical crossover response.

Think of it like this:

If someone handed you a box full of passive componets what would your chances of coming up with an optimum design be by just listening or just measurements?

It's the same with a active crossover except the beter DSP crossovers/equalizer are so much more versatile and complete in it's ability to optimize the acoustical crossover region.

mike tn

[mikebse2a3]

BTW, I was already aware of the pitfalls of auditioning a speaker in room full of other speakers. That is not a good way of judging how a speaker will sound in a room by itself. You are correct in your impression of the effects other speakers make in a room. Particularly when a large number of other speakers are present.

Just to be clear, my point was up to a point all those speakers were in fact acting as acoustical treatments (modal and diffusive) that this room and all rooms need so that we are able to perceive the cues necessary for imaging and soundstaging.

mike tn

[mikebse2a3]

I have listened two one genuine system and one clone system. Neither bass bin produced near the bass impact my Khorns produce, and no, my bass is not boosted in any way. In fact, Audyssey reduces my bass output.

I understand Rudy81. Again,as I know you are aware, the Klipschorn or Jubilee are one with the room and ultimately what is acheived is the marriage between the two.

I'm fortunate and have experienced Jubilee's and Khorns in direct comparisons in the same rooms and no longer have to wonder because of unknown variables like different rooms/equipment.

I would also like to point out that if one compares the design and measurements between the Klipschorn LF and the Jubilee LF the Jubilee clearly is closer to an optimized design in it's folding alone and part of the proof is in the lower distortion and smoother and more extended frequency response.

Again please understand I'm just discussing what I know to be facts, my understandings and my experiences with the hope of helping and learning something myself.

And PLEASE understand I'm not pushing the Jubilee, Active Crossovers or anything else. I'm simply enjoying a good conversation about these different subjects.

Active crossovers are like a refinement probably best done only after attention has been paid in many other areas of loudspeaker design and considerations of the complete audio reproductin chain IMHO.

Man I've got to get off this computer and get something done..!!!!....continue without me for awhile...[]

mike tn

[ClaudeJ1]

Just to be clear, my point was up to a point all those speakers were in fact acting as acoustical treatments (modal and diffusive) that this room and all rooms need so that we are able to perceive the cues necessary for imaging and soundstaging.

mike tn

Mike, you are forgetting that he is using the Audyssey EQ, which, in my various horn setups in the last few years, has made as large of an impact on the sound as the room itself irrespective of driver/crossover changes, etc.

Audyssey works in both the frequency and time domains, and does a heck of a lot of "voodoo" to the sound automatically. That's why I call it "EQ for dummies." It really works if you work it right.

[DrWho]

What you say about acoustic centers shifting with
frequency doesn't make any sense and betrays a complete lack of
understanding of the Synergy design. Please explain how I'm wrong
here.

http://www.aes.org/e-lib/browse.cfm?elib=8194

There are other references to shifting acoustic centers in the
literature...I spent a while searching, but couldn't find any of the
specific articles that I originally read. However, all horns (to my
knowledge) have shfiting acoustic centers with frequency and angle of
measurement. It seems like it's not fully understood why this is the
case, but my theory is that the wave velocity isn't the same everywhere
in the horn...

As far as the synergy concept, take a look at
how the polars bounce back and forth between the various drive units.
Also, you should try doing your string experiment with all the
different throats in the horn... []

For the record, I'm not at
all a fan of line arrays. However, the reason I brought it up is to
point out that there is merit to calling the wavefront of a line array
a planar wave when it in fact is not by an overly specific definition.
There is criteria to where it behaves like a planar wavefront and under
those conditions it is completely acceptable for an engineer to treat
it as such. Engineering is not science...

I'm not trying to be
nit-picky or dance around or whatever, but it is very difficult to
communicate when we're not speaking the same language...

And also
for the record, I'm also a fan of the synergy horn concept, but it
doesn't change my opinion on time-alignment in a 2-way system...