First order/Time Phase-Coherent speakers discussions


"The game is done! I’ve won! I’ve won!"


I would like to use this thread to talk about this subject which I find rather fascinating and somewhat difficult to get my hands on. I went through a course in electromagnetism in college and I have to say this is even more confusing and you won’t find the answer in calculus, physics, Einstein relativity be damned it’s not in there either and definitely not in quantum physics. Listening to the "experts" from Vandersteens and Stereophile but ultimately it all came down to a missing link sort of argument ... something like this:
"Since if a speaker can produce a step response correctly, therefore it is time-phase coherent, and therefore it must be "good".

It’s like saying humans come from chimps since they share 90% genetic content with us, but we can’t find any missing links or evidence. FYI, we share a lot of gene with the corn plants as well. Another argument I’ve heard from John Atkinson that lacks any supporting evidence and he said that if everything else being equal, time-phase coherence tends to produce a more coherent and superior soundstage, but to the best of my knowledge, nobody has been able to produce some semblance of evidence since there is no way to compare apples to apples. Speaker "A" may have better soundstage simply because it’s a BETTER design, and the claim "time-phase coherent" is just a red herring. There’s no way one can say the "goodness" from "time-phase coherence" because you can’t compare apples to apples. Ultimately it’s a subjective quantification.

I’ve been doing some simulation and I will post some of my findings with graphs, plots, actual simulation runs so that we are discussing on subjective personal opinions. Some of my findings actually shows that intentionally making time-phase may result in inferior phase problem and NOT better! (will be discussed more in detail).

Having said all that, I am actually in favor of first order/time-phase coherent if POSSIBLE. I am not in favor of time-phase coherence just for the sake of it. It’s just that there are a lot of mis-information out there that hopefully this will clear those out. Well hopefully ...

Here my preliminary outline:

1. My "subjective" impression of what is "musicality" and how it’s related to first order filters.
2. Interpretation of step-response. I’ve read a lot of online writing with regard to the interpretations but I think a lot of them are wrong. A proper interpretation is presented with graphs and simulations.
3. A simulation of an 1st order and higher order filters with ideal drivers and why time-phase coherence is only possible with 1st order filter. This part will use ideal drivers. The next part will use real world drivers.
4. A simulation with actual drivers and how to design a 1st order/time phase coherent speaker. Discuss pros and cons. And why time-phase coherence may actually have phase issues.
5. Discuss real world examples of time-phase coherence with Thiel’s and Vandersteens speakers (and why I suspect they may not ultimately be time-phase coherent in the strictest sense).
6. I’ll think of something real to say here ... :-)
andy2
By the way,  to be clear: 
Absolute phasing is IMPOSSIBLE. 
You can get phasing done at the crossover point which is the goal.  
a woofer playing bass at 50 cycles will move at a different rate than a tweeter playing at 15000 cycles. 
When we align phase at the crossover points, that is as close as you can hope for. 
I hope this helps,
Tim 
Andy2 I appreciate this topic. I know very little about it. Nice to know a little more about what effects the challenges of our speakers.
Just to mention I am pretty sure Timlub has spent many years I think designing, and building speakers. He has a lot of reasonable knowledge and he is very helpful. He can help us a lot along this topic.
Thanks Timlub. And I may have short changed how much Timlub knows about speaker development and execution on a high level. If I have I am sorry.
I hope that I have expressed this in a way for everyone of any level to understand
As an anecdotal personal experience, for awhile I was learning how to cook, so either I have to take some cooking classes, or being cheap as me, I would look up at a bunch of YouTube vids and learn how they do it.  Natural I would look at vids from the famous chefs like the guy in Kitchen Nightmares and the likes.  But my results were terrible and I hated the tasting.  I then looked at the vids from regular folks figuring out they would be at the same level as I was.  But I eventually found out that most of them basically would watch some other YouTube vids and emulate them and put up their own vids without knowing if their recipes would taste any good.  I think they would just pick some random recipe, went grocery shopping, and made the vid almost like copying and pasting.  I think most of them  just want their face on YouTube and not really caring if their recipes would taste any good.  So I gave up on that too.

So I ended up deciding that I would just follow my own instincts, you know like Luke SkyWalker.  I've nailed down to a few my go-to recipes that I've developed over the years so at least I don't hate my cooking anymore.  Now I have a bunch of healthy recipes that I can use.  I actually enjoy my cookings more now than restaurant foods.  The only problem now is I still can't make my own beers or wines.  Well you can't have everything I guess.  

Damn, I thought that I would just cook like the guy in Kitchen Nightmares by just watching his vids lols.

So what's that has to do with time phase coherent?  I am not telling until I am properly wined and dined as one of my dates once told me. :-)  

All drivers moving in perfect unison.... when one driver starts moving outward, all drivers move outward at the same time, when it comes back, all drivers move back at the same time.
Physically is it possible?  For example, the woofer flapping at 70Hz, the tweeter flapping at 7KHz.  For every woofer moving forward and back, the tweeter is moving 700 time back and forth, so it's not possible right?

One reason that a single driver does so many things right is that there are no phase issues.
That's not entirely true.  A driver may have different phase shift at different frequencies.  For example, a driver may have a relative phase of 10deg at 700Hz, but at 7KHz, it may have phase shift of 80 degrees.  Not to mention different parts of the driver may not moving "at the same time".

Anyway, I spent too much time watching cooking vids to have time for time-phase coherent stuffs ... hahahahaha
I don’t want to put words in your mouth, but I think you mean that a mid-woofer playing a 50Hz tone and a 1KHz tone will only be at the same position in space (phase-aligned) as the midrange playing a 1Khz tone, for part of the 50Hz cycle? ... or for any two speakers whose sound is integrated.
A microphone element is thin and does not move much, so alignment of the center of movement for all frequencies is most important in playback to recreate what is recorded.



timlub1,704 posts10-31-2019 2:02pmBy the way, to be clear:
Absolute phasing is IMPOSSIBLE.
You can get phasing done at the crossover point which is the goal.
a woofer playing bass at 50 cycles will move at a different rate than a tweeter playing at 15000 cycles.
When we align phase at the crossover points, that is as close as you can hope for.
I hope this helps,
Tim


Just to mention I am pretty sure Timlub has spent many years building and I think designing, and building speakers.
The only skills I need right is how to get to Ms. Kate Upton.  Now if he can get that done, he's my guy lols.


A single driver does a lot of things right, but has other issues that are hard to overcome such as doppler induced IM distortion. I.e. a 100Hz tone will modulate a 1KHz tone.

One reason that a single driver does so many things right is that there are no phase issues.
That’s not entirely true. A driver may have different phase shift at different frequencies. For example, a driver may have a relative phase of 10deg at 700Hz, but at 7KHz, it may have phase shift of 80 degrees. Not to mention different parts of the driver may not moving "at the same time".

a 100Hz tone will modulate a 1KHz tone.
I'd like to know how that feel ... errr I mean how that sounds like.
This thread is getting good. Looks like most of the trolls have jumped ship.

Timmy boy. I would like to disagree with you, respectfully. Perfect phase IS possible.

I studied Jim Thiels CS5 crossover. The man was a genius. He used an extra 10+ capacitors to phase match the signal. Let me explain; when an alternating current (sinusoidal waveform for music) goes through a capacitor, voltage lags current by 90 degrees. If a single capacitor is used on a tweeter, it's only the +ve portion of the waveform which is affected. What do we do about the -ve portion of the waveform?. Mr. Thiel was able to 'see' the phase of the music, and manipulate the -ve portion to match the positive. At this point, speaker designers will say "wait, the speaker drive is part of the circuit, and it is irrelevant where the capacitor goes". Opps, the speaker driver is not 'in circuit', but in fact is a 'load' on the circuit. Mr. Thiel understood this, and I am a fan of his speakers.

Gauder Akustic? have designed a symmetrical parallel crossover. When driven by a balanced (symmetrical) amplifier, their speaker is close to phase perfect.

A Linkwitz Riley 2nd order series crossover, with drivers acoustical centers aligned, is phase perfect.

The problem? very few people have heard these speakers. 

Timmy boy. Judging by some of your posts, you know wayyyyyy more than you are letting on. Your post on degree shifts is bang on. Too many speaker designer ignore this. Mr. Joseph of Joseph Audio also understands phase. I love his speakers.
OK, if you indeed called me "Timmy boy", you’re probably gay. Then you probably knows wayyyyy more. Then why don’t just spill the beans?

Hey you should pick on someone you're own size :-)  Mines are too big.
@geoffkait , and time incoherence is when the clock passes through one’s head?

Just as I thought....*stare into the middle distance, drum fingers on desk....*

Ok....just to muck stuff up and soil the water...

I’ll assume the discussion is predicated on ’typical’ drivers on a vertical plane. ’Time alignment’ addressed by physical alignment of the voice coils; ’phase align(or mis-align)ment’ introduced or effected by the choice of crossover or selection of drivers characteristics to minimize or eliminate the use of a Xover...if such is possible...

Now, What If....

The driver voice coils are vertically aligned physically, ’stacked’ one above the other, drivers facing Down. Time coherence, check.

(geoff recognizes where I'm going with this...or he ignores me better than I assume...*s*....)

What happens to phase in this scenario? Will 90~180~360 be a minor/major issue? Will a Tice clock thrown at this disappear?
Will I disappear and stop being an annoyance?
(Not f’n likely, but amuse yourselves with that....)
Let’s start with your comment about capacitors. Assuming the capacitor is bipolar, which pretty much all capacitors in speakers are as well as many audiophiles, it works the same in both directions of the AC signal. Voltage lag is not 90 degrees, but may be 90 degrees at some given frequency.

On the second point, to a speaker, all amplifiers are essentially balanced. There is no ground reference in a speaker, so the speaker has no concept of what single ended or balanced is. It is getting some sort of AC signal.

On the concept of "perfect phase", it sounds like a nice concept, except the lower and upper drivers have different excursions for a given power level, the lower driver could be playing the high frequency superimposed on a low frequency that moves the speaker in and out of phase at the high frequency, etc. When you move to the digital domain, there are techniques to correct for more of the issues.
cousinbillyl172 posts10-31-2019 5:29p
Let me explain; when an alternating current (sinusoidal waveform for music) goes through a capacitor, voltage lags current by 90 degrees. If a single capacitor is used on a tweeter, it’s only the +ve portion of the waveform which is affected.
Gauder Akustic? have designed a symmetrical parallel crossover. When driven by a balanced (symmetrical) amplifier, their speaker is close to phase perfect.



physical alignment of the voice coils
a good start, but my requirement still not met

minimize or eliminate the use of a Xover
not really likely, consider xover is a necessary evil

driver voice coils are vertically aligned physically

I don't care, but sounds fantastic got my curiosity?

Will 90~180~360 be a minor/major
Too many variables, need more information to fully understand

Will I disappear and stop being an annoyance?
It's your money, your time who am I to say

  (Not f’n likely, but amuse yourselves with that....)

If f'n involved, be my guess be f'n around

@andy2 ...*L*  Oh, goody....R/T 'engagement!  Or close enuff'...

I've been DIY'ing Walsh speakers for awhile now; not the current Ohm variety, but closer to the original F's and A's and the HHR in intent, But...

Size of the 'main' driver is larger than HHRs' smaller 'stand alone' driver and the German Physiks, covering the 'upper mids through upper bass'.

Hand off the lower bass to a sub...they're more efficient at it (and, MHO, most of the reason folks blew up the originals, due to cone collapse...) and bass being omni by nature anyhow...

High end:  a smaller Walsh, lighter cone, based kinda like the Infinity 'ice cream cone' driver of awhile back.  I've chatted with one who 'was there' in the creation of it, literally done on a kitchen table.  We've traded stories, both on and off topic... ;)

Tweet above main, vertical alignment.

I have working prototypes....working on Better.

"Be Afraid..." *L*  Not many have heard IRL....those who have, Like.

Any thoughts?
I owned a pair of Infinity's with the ICC driver....pointed out that it was upside down on or in the cabinets.  The rationale for that was that they were too 'price driven' to mount them properly....

The only way you could hear them was to lay on the floor...
....which, back then, we did...occasionally....

SF in the early '70's....get the picture? *smirk* ;)
Any thoughts?
The Walsh and HHR and full range exotic driver stuffs you mention are a bit out of my depth.

And I am not familiar with some of the references in your post.

I am more into conventional cone drivers and speakers - like the typical Seas of ScanSpeak stuffs.

May be if you have a link that can show some pictures of your prototypes then hopefully I can chime in or maybe learn a few things.  I am more of a visual thinker.  


@cousinbillyl 
You are correct about a lot of your phase conversations.... I spoke with Jim years gone by..... you might remember or go find up the thread where I said something like you can get a 1st order down to around a 15 degree phase shift??? that's what Jim did,  he did remarkable work taking a 90 degree shift down to 15 degrees.  
I won't argue,  but I will say that I've never seen absolute phase alignment between drivers without electronic crossovers. 
I won't argue, but I will say that I've never seen absolute phase alignment between drivers without electronic crossovers.
In my past experiences, most competent engineers will figure our how to "fix" it.  But the difference between a merely good engineer to one who can actually make money is that he understands the consequence of his "fixing".  

Ever heard of stories of a mad genius?  They all know exactly how to "fix" things, but nobody hires him because he'll end up breaking more things than fixing.

Hence I fear ... I fear ... I fear ... the electronic crossovers ... will they turn all my musics into mp3?  Will they cause mad hysteria and drive me to insanity?
@andy2 ....well.....you've likely been to concerts....outdoors...they use electronic crossovers with utter abandon....

It's the only real means to make all that stuff behave, make the beer swigger behind you bellow like a beast because of the 'axe solo' he/she/'it' just have trample their neurons into some version of 'audio nirvana' that 'us puristas' abhor the response to....(as we sip our merlots, transported by our multi-$ private systems...) *LOL*

Yes, I'm being vaguely 'snotty' about that, but it is the same sort of insanity; basically, Good, and Good for You....and Them.

It's only the 'pink noise' of the audience response...the yelling, applause, whistling, and general racket that's driven me to take 'roadie' and other 'specialized' earplugs to concerts, keeping my hands near my shoulders to save my hearing for why I'm there in the first place. *chagrined G*

Timing becomes All.... ;)

If you go crazy. well...  I guess you can stay home.  Not go to clubs either.
Or any public events, short of chamber music....nice, Quiet stuff...

Yes, being facetious...*sad S*

"Poor Andy...can't take him Anywhere...*long sigh*....

Here...
https://www.youtube.com/watch?v=10HjqHXpZtU&feature=youtu.be

This is old...there's been 'improvements', and more pending.  Read the comments.  Primitive, yes.  Less so now... ;)

...'course, you're listening in mono to omnis thru a camera with a lousy mike.  Think of a sunset taken with a pinhole camera onto b&w film, and processed in the sink.

...and it's 4 years ago....;)
Go listen to where I first ran into the music played behind the 'ride'....;)

https://www.youtube.com/watch?v=xQ_IQS3VKjA

Beautiful music, a lovely vocal, and stupendous scenery....*S*

Pity all 3 are dead now. RIP, y'all.

But the Ridge remains...
The problem with your perfect single driver is that it ain’t, in fact very very very few purpose built narrow bandwidth drivers are pistonic. Most paper cone single driver speakers are out of phase a LOT
see the Vandersteen video of the German laser scanning machine of the 7 midrange vs another highly regarded midrange....
making an efficient pistonic driver is the holy grail.
getting cheap high trash output out of a single driver w big motor not so difficult 


@tomic601 ...and why I'm trying to avoid 'pistonic' as much as practical..given frequencies, and how they're recreated...

A sub for major air movements...anything above is fair game. *G*
"Poor Andy...can't take him Anywhere...*long sigh*....
Hey I'll go if you're really hot ... but sigh ... there's the reality :-()-:
making an efficient pistonic driver is the holy grail.
The only part I care is "holy".  "grail" blasphemy :-()-:
The hardest parts of the journey are the beginning and the end.  Still working on the introduction.  Damn it's hard.

Oh God Devil you

Oh duality devil you

He invented taken he

She yang yin less


Want coherence clarity not

Want time frequency not

She makes ruins him

And she he nods


What first second then

What fire ice followed

What desire hate you

What you you last


For excellent tutorials on loudspeaker design, watch the You Tube videos on the subject made by Danny Richie (GR Research) in conjunction with Ron of New Record Day fame.
@bdp24 , Thankx, I'll go stare @ that....and ignore what I don't think applies. *L*

I do that.... ;)
Walshs' are Not Normal....

I've been accused of that...but it works for me.  Thinking 'outside the box' is easy when you don't believe the box really exists... ;)
...and @andy2 has a 'poetic interlude'....*G*

Lets' drift 'off topic' for a moment....*S*  Good for the soul, tics everyone else off...*L*
Even if you have perfect pistonic motion, you still have intermodulation distortion with a pistonic driver. It is unavoidable.
@atdavid...yup, there's the points where the driven surface has to slow down, stop, and accelerate in the opposite direction.  'X' x per second, constantly varying....
I'd get distorted too, which occurs with far simpler motions.*L*
There's various 'this 'n that' applied to compensate, but none make it 'go away' completely.
The above is why a Walsh radiator appeals to me.  Pistonic motion is primarily converted into a radial radiation at the voice coil/cone interface.
It doesn't 'go pistonic' until the waveforms descend further down the cone, where the diameter of the cone is less likely to radial excitation of the surrounding air...
Think of a bell...stuck, it vibrates radially.  In this instance, the cone needs to be light but physically stiff to endure the induced waveforms. That requires a driver that is under a considerable amount of resistance.  Which translates into heat...which will fry most voice coils.
I've lost a couple that way...a finger on the magnets' backside gets hot to the touch.
That's one thing that I've worked to address, as well as the cone materials, cone interior reflections, surround material selection, et all...
Even the choice of structural material is not typical; stiff, yet absorptive.

There are those that consider omni's 'non-starters', but consider the nature of 'live music'.  It doesn't exist as a sound from a plane; it's omni by nature, as you are.  You hear from all around you, reflections and all.
Crossovers don't exist either...*s*
Yes, omni's are a bitch to set up in a given space. *shrug*  But, given that many spend big $ to 'condition' their listening environment, what's the diff?
I'm a fan of Linkwitzs' comment: "Ignore the room."
Which is why I approach the issue by 'going 5.1', a surround array with a sub.
Direct overrules reflections when you're in the midst...;)
I have followed B&W since the company was founded.  You can measure time phase differences.  When B&W began, all the profits went into laser and computers.  They measured the electrical signal and compared it with what the laser showed came out of the speaker.  The they bought some KEF three way speakers, and designed a better crossover, marketing the product as a  Domestic Motor.  This speaker used the same drivers as KEF, their oblong woofer, a Celestion upper midrange/tweeter, and a Coles super tweeter.  The woofer was designed to be narrow for tax reasons, because the British Value Added Tax wa based on speaker width. Their second speaker only changed to a round woofer.  The DM 4 ported the same box, instead of the lot, and turned this speaker upside down, which it should have been from the beginning, because it was a bit large to put on it side on a shelf.  Further research, with evolving better equipment showed that phase alignment created a more coherent sound stage, begatting the DM6, affectionately known as The Pregnant penguin.  The DM 7 and DM14 were next, with the position of the exposed tweeter of the 17 drawing a lot more attention than using electronic time delay, which also a had the issue of only working in a frequency dependent way.  The rest is history, but includes better and better measuring equipment, materials, beveled cabinet edges (explaining why the wood Advents sounded better than the vinyl ones), then the sound deadening of the Matrix cabinets.

Phase alignment is certainly measurable.  
...much like real life...

What’s in the YT video is the basis of what I’ve been pursuing; a 2-way column, close proximity of the drivers, height to take advantage of the ’angle of radiation’, spare construction. Appearance in the long run will be a simple ’lipstick’ fabric column of fabric.
Not ’cat-proof’ to begin with...don’t have any at this time... ;)
Form following function...
Phase alignment is certainly measurable.  
its all a myth. Most important thing is frequency response. 
I always thought the goal was having 20to20 arriving at your ears, at the same time and in phase. Many ways to do this. Wasn't Mirage one of the first to put an out of phase tweeter on the rear ?
@danvignau234, I liked 'Domestic Motor'. *G* So...'householdy'...;)
@kenjit, a myth, and into the mystic. Smoke, mirrors, obtuse formula....
@viking62....what era for the Mirage?  The Infinity I noted had a 3' typical cone tweeter on the back as well.  The intent of the unit was to have a more 'airy, holographic' quality...

It was an interesting go at it....basically a 5 speaker, '4 way'. It could be done better these days...
“Not everything that counts can be counted, and not everything that can be counted counts.”  Einstein 
For those who love to over complicate things, this one for you from Einstein the man himself.  

"Everything should be made simple, but not simpler."  Einstein
And of course keep this in mind for those who love DSP and stuffs.

"Don't get lost in the forest while trying to find your tree"  Kate Upton
Relax and smell the coffee in the morning.


I always thought the goal was having 20to20 arriving at your ears, at the same time and in phase
They do. Theres no evidence they dont. 
@andy2 , I used to carry a thermos with a biohazard sticker on it.
It didn't stop those from asking for a 'hit' if the night previously had some sort of 'adventure'. ;)
As for 'simple'>'not simpler', just enough of the 'right things'.  Where one draws the line is the issue... I opt for 'minimalist', just enough.

@kenjit , yeah, but many will argue...excuse, 'discuss' the experienced results just the same. *G*  It's the interpretation 'twixt the ears that appears to be the crux of it...

My fav 'case in point': White people.

Look @ your hands.  That is Not 'white', in the classical sense.
Beige/pink/l. brown-yellow in varying amounts.  Not even 'even'.
Where one draws the line is the issue...
Those who have more juice .... errr I mean money get to draw the lines.  Always have been the case.

It's the interpretation 'twixt the ears that appears to be the crux of it...
Read two or three line above.

My fav 'case in point': White people.
Read four or five line above.

Look @ your hands. That is Not 'white', in the classical sense.
Beige/pink/l. brown-yellow in varying amounts. Not even 'even'.
Read seven or eight line above.

Conclusion: More juice more win.
"Money changes everything.... C. Lauper
Same subject, different song, SOS...*L*
Andy2: "I’ve been doing some simulation and I will post some of my findings with graphs, plots, actual simulation runs so that we are discussing on subjective personal opinions. Some of my findings actually shows that intentionally making time-phase may result in inferior phase problem and NOT better "

Please follow through on posting these data. Why simulations and not real data from speakers.


Some of my findings actually shows that intentionally making time-phase may result in inferior phase problem and NOT better 
I think that was also what I said in my original post.  What I said that everything else being equal, then yes, time-phase coherent is a plus.  But I also said that I have seen examples in which the designers tried to make time-phase coherent at the expenses of other parameters such as phase-mismatch or frequency response that may end up creating more problem than it solves.

It seems that Thiel (an I am being VERY careful not to appear to make any false accusation) has claimed that the company's speakers have very small excess phase, which means that the phase shift of the entire frequency range (from 50Hz - 20KHz) has very minimal phase shift, and based from Tom, within a few degrees.  Now that is EXTREMELY difficult (trust me) and I do not even think it's doable or even REAL.  I tried to model one of my speakers like that and I could only achieve about +/- 25 degree but I had to bend over backward to get that done at the expense of freq. response and proper driver integration.  Therefore I really did not like the design and I think I am better off with a more conventional approach.  But having said that, there may be about 2 or 3 speakers in the world that can have +/25 degree excess phase.  John Atkinson had said that you can count will all the fingers in your hands the number of speakers he measured that can get a proper step response which is pretty hard in itself.  But having a proper step response AND having 0 excess phase is like winning the lottery every single week.

For reference, if you use 4th order (24db/octave), you automatically get an excess phase of at least 360 degree.  If you do a regular 1st order but with one of the driver inverted, you probably get about 180 degree of excess phase.  To have zero excess phase (or close to zero as claimed by some) is like hitting a bull's eyes from 7Km away.  I think you can count with five fingers the number of speakers in the history that can achieve 0 excess phase.

When you look at the step response from John Atkinson measurements, it's easy to spot if a speaker has too much excess phase.  Even if a speaker can achieve a proper step response, if the initial spike is too "spikey" vs. the rest, then it probably has too much excess phase.  I've seen various measurements of Vandersteens from Stereophile, I doubt they are qualified as "time-phase coherent" across the entire freq. spectrum.  Maybe from 50Hz to up about 7Khz but not all the way to 20KHz.  And I also posted the CS3.7 measurement and showed it to Tom and I said I doubt about the claim as well.  

I have quite a few real world data and simulations but I am waiting for better Confirmation before posting the data since I don't want to be accused of not have REAL or FAKE data.  I've heard of a lot of people including all the experts in the world talking about it but at the end you get even more confused!  Maybe it's a secret and once you know it, you don't want to share.


"...thinking of something Real to say here..."
*mmm*
Well, if you haven’t illustrated succinctly the issues and complexity of any attempts to resolve the time/phase-coherence Gordian Knot as it relates to any speaker array, I think I’ll have to be patient to read it....
...and I will thank you for that. *S*
"...I tried to model one of my speakers like that and I could only achieve about +/- 25 degree but I had to bend over backward to get that done at the expense of freq. response and proper driver integration. Therefore I really did not like the design and I think I am better off with a more conventional approach.."
Volumes in 2 sentences...;) So, in my ’unconventional approach’ to my ’quest’, I may have to default to @cousinbillyl ’s comment:
"A Linkwitz Riley 2nd order series crossover, with drivers acoustical centers aligned, is phase perfect."
The line that follow that is also interesting....at least, to me. ;)

What I distill from your post is that if one designs to correct All that one can correct, what one May end up with...you won’t like to hear...Perhaps.

You Might get lucky.

The odds are towering against you.

Now....that’s Quixotic in the extreme.

...from @ivan_nosnibor , awhile back...
But, with active digital crossovers, there’s no need to spend all that time reading all the tea leaves (white papers, testimonials, reams of MLSSA charts, searching for who could be the most unimpeachable source of info on it, etc) in an attempt to get a handle on comparing them all from afar and then try to divine which might be best. With digital actives, you just dial it up and listen for yourself...a whole lot easier and faster that way.
I’ve got one of those...active eq as well (been doing that for decades now, like to play ’flat’ into the space as much as is practical). I think I’ll just wander off with all of this in mind and at hand...

...and see (well, hear) what I can conjure up. *S*

@andy2 ....I think that a digital Xover..."...is our only hope!" ;) *smirk*

Good variable factors, Obi Wan.
And thanks....to you, and all the posters quoted and read.
I may not have a road map, but I may have a destination to target.

[lurk mode engaged]
My wife can't hear the difference. She thinks I'm an idiot.

trust me you don't have to be 'ocd' to fall into that camp.

I recently came across a pair of vintage DCM TimeWindow 3 speakers. Phase and time aligned, by designer Steve Eberbach.

TO MY EARS, they sound great.  The usual superlatives: can hear more details, voices are more real, brushes on a drum more realistic.

I had to sell off my modest system a few years back: C22, MC275, Vandertseen 3A signatures.  Heck, I thought I was in heaven, then.


Well, I now hear at least the same detail and more, especially on the upper end from these TimeWindow 3 speakers.  (Guessing the 3As were "laid back"?) 

I pulled out my old Carver (don't laugh!) TFM-35x from the 90s.

Carver C-23 pre-amp.  Same old Rega Planet CD player! 

I did A-B testing years ago between the Carver and McIntosh amps. Very little difference.  Bass tighter with the Carver. Possibly a tiny bit better midrange with the MC275.  But one beer equalized everything!  lol!

So, if you look around what's the most traded, bought and sold  audio components?  Yeah, SPEAKERS!   Everyone looking for nirvana, since all our ears are the same, but they are all DIFFERENT, like fingerprints!  

FOR ME, I believe I am sensitive to more correct phase and time alignment factors, whatever they are, however you explain them!

If you can listen to speakers for about 4-5 hours without fatigue, they work for YOU!! 

For the record, my ears can't hear past 13K.  (going on 64 years old)

If you get yours tested, you'd be surprised how little you can hear on the upper end.  Not to mention most guys don't have a flat response curve!


Nice thread read. Never to old to learn stuff.   Now, get those ears tested and maybe you'll figure out why you prefer certain speakers over others! 

Hey, people I got a little secret want to let you in.
assvjerry posts were all done while drunk lols.

I may not have a road map, but I may have a destination to target.
Oh good lord.  See what I meant.  A drunk with no road map.  

For the record, my ears can't hear past 13K. (going on 64 years old)

That's true.  I can't hear past 15KHz.  But I am pretty sensitive to speakers with high frequency issues.  Why? (Read below)

If you get yours tested, you'd be surprised how little you can hear on the upper end. Not to mention most guys don't have a flat response curve!
But not to worry.  Most of meaningful music lies much below that.  My speaker has a rising freq. from about 7KHz.  At 15KHz it's 5db above the rest! and I swear it doesn't sound bright at all.  And I am listening almost on-axis with toe-in.  

But IF that 5db was around 3KHz, you'll or I'll be running for cover.

Treble starts at much lower frequencies than people think.

People hearing is very sensitive around 1KHz - 3KHz.  A slight bump in this freq. range will be very audible.  It's like running fingers on chalk board.

In general, 6KHz - 8KHz is sibilance if the speaker is excessive at this freq range.  A bit high will make the  neutral ssssshhhhh to ssssssshhh.  If too high will be like sssssssssh.  When you hear actual people talk, you don't hear sibilance unless they talk straight into your ear.  

8KHz or above, we call "air" or whatever that is.  After 10KHz, unless it's very excessive, most people probably can't hear.  I guess young people could.  And I am sure some people are more sensitive than others, but in general, most people especially old are not very sensitive above 10K.  

Some tweeters are designed intentionally to have a bit lift above around 13Khz to artificially give an extra "air" to the sound.  I actually hate that they do that.  I prefer a more neutral freq. response.  If I need more air, I can do that myself thank you.