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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

Showing 7 responses by ivan_nosnibor

ivan_nosnibor's avatar
ivan_nosnibor
1,054 posts
 
@timlub +1

"With a active crossover, time/phase alignment becomes relatively easy."

Agreed, and as someone who has those, if their frequency selection allows any choice from 20-20k which mine do, then it's a simple matter for me to just think up a combination of frequency selection vs slopes to play around with various drivers and compare the results on the fly from the lp.

Does 1rst order have advantages? Sure. But they have disadvantages, too, like all the other slopes. I've experimented from 1rst to 5th order (LWR, Bttrwth) and can tell you easily that, for sound's sake, I would never start with a crossover design and try to pin it onto a pair of drivers. I'd have to start with the real-world drivers and come up with the right crossover. I'd certainly consider what the crossover might look like when choosing drivers, but that's only all the more reason to give the driver selection the most consideration from the start. But, 1rst order behavior advantages are not the only consideration to good overall design.

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.

What I can tell from that is, yeah, 1rst order can be nice, but it's not the holy grail. The holy grail is a well orchestrated and executed speaker design overall...not just one or two aspects.
ivan_nosnibor's avatar
ivan_nosnibor
1,054 posts
 
"There is still some or even a lot of reading on digital if you want to start pushing the limits / doing custom FIR filters, etc.
Digital is for low end stuffs. High end and expensive stuffs are pure analog. Consider it a lesson."


That used to be true, but that particular part of the landscape may be changing. The only true weakness for digital (as long as it has all the proper inclusions of capabilities, which don't they always have) is the sound quality. That's been true of CDP's, DAC's and everything else digital...only there, sizeable advancements in sq have been made through power treatments. And digital crossovers should not be left out of that picture. Power treatments, particularly the quantum kind (which don't have all the weird side effects that component-based [caps, transformers, or other parts] power conditioning does), are beginning to change the game in favor of digital in general. It adds to the cost, but it compares extremely well to the best analog, when done sufficiently well.

"With digital actives, you just dial it up and listen for yourself...a whole lot easier and faster that way.
When someone claims something is "a whole lot easy", I go like "hello, what has he done?""


I'm talking about sitting in your listening chair (with at least a mockup of the speaker design in front of you) and then going through the listening/evaluation trials of whatever drivers-vs-crossover recipes you might want to investigate...maybe make some measurements with Omni-mic to confirm some things and you should have most or all of your answers right there...the process shouldn't even take you one, whole day to test, if all goes well. You may not be able to actually measure, say, the waterfall plot of the finished design (I suppose you could if had the right test gear), but you might be amazed at just how far down the road this will take you toward a solid, finished design in one take. I tend to go through this same process several times on different days so I can average out my own moods, predilections for listening for different traits, listening awareness levels and so on, in an effort to help me take my own fallibility out of the equation. But, you get an excellent feel for things like step-loss issues, phase issues, dispersion and all the rest of it, all at once. I used this process to design a pair of open-baffle stand mounts, which are not hard to build anyway, but if you're looking to build some giant-sized box, then you would have to make a good enough mockup to listen and test with.
ivan_nosnibor's avatar
ivan_nosnibor
1,054 posts
 
"You can’t be so desperate, can you? Are you saying "stupidity" is what you’re waiting to save you?"


Uhh...No. That refers to your wanting to berate or challenge anyone who is not answering your questions, particularly the unanswerable (what does it sound like), to suit your impatience, and then getting irate at the answer when it comes. You’re acting a bit like a drowning man who’s spitting at anyone who tries to throw you a life preserver. That’s pretty stupid, even for a forum.

But, if you’re saying that’s not stupid for you, then I’ll take your word for it...I guess.
ivan_nosnibor's avatar
ivan_nosnibor
1,054 posts
 
Well, I suppose I'm tired already of the ramblings of an 'educated' man who can't think his way back down to earth long enough to answer his own question...ya got me there I guess. 

My hat's off to you, if you can fly as high on yourself as you claim to and still not know how to fix your problem.

I'd say your first blow up in your thread 'started' it, you just snowballed from there.
ivan_nosnibor's avatar
ivan_nosnibor
1,054 posts
 
The way you treated me I could expect, my problem was with the way you treated everyone else here.

Like about everyone else in this thread before me has figured out and gone (where are they now), you're long on making a splash and short on contributing anything useful. There were plenty useful comments here to make a good thread out of, but you were only interested in what you think you know, as others tried to tell you.

But, for everyone here and any exchange of ideas, you were too much of a headache and too much of a PITA...I'll leave it to you as to how that pairs up.

I think I'm out.
ivan_nosnibor's avatar
ivan_nosnibor
1,054 posts
 
@andy2 looks so far like you’ve come to this thread demanding some answers (you keep flailing away at the one practical-based q[what does it sound like?]). It’s one thing to want answers, everybody in this forum does, but it’s another to just plop down in a thread and bitc# and moan and blame everyone else for the fact that You don’t understand something, like we’re supposed to think you’re ’spatial’...you seem to think that Your ignorance is somehow Our fault.

You probly would’ve had more support if you had accepted responsibility for that from the start, but you evidently decided in advance that all of us are b@stards from the start for not telling you what it is you want to know.

I think at this point someone could give you the answer you’ve been looking for all along and you’d have too big of a chip on your shoulder and be too stupid to recognize it. Personally I have no interest in whether or not you ever do recognize it...and I don’t think anyone else here should either.

Yeah it’s Friday. And tomorrow’s Saturday and the next day is Sunday...I for one, don’t especially care how long it will take you, or how old you will turn out to be, before someone ’Finally’ leads you by the hand and delivers you (and the rest of us) from your own stupidity.

Have a nice weekend.
ivan_nosnibor's avatar
ivan_nosnibor
1,054 posts
 
Look, I'm not out to dog you to hell and back. I'm not asking you to change your style or anything...just try to be just a Little more respectful of everyone else's point of view...maybe even if you don't entirely agree...maybe offer a civil but rational response that might explain your objections in the terms they presented??…just a little more give and take maybe?? 

That's all I'm trying to say.
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