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
"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.
A decent active crossover in knowledgeable hands will crush the performance of a top tier passive crossover.
Haha so much crushing that nobody is bothering doing it except for some cheap eight dollar headphones.  Real life hello?
Anyway, let's put it to rest.  Hi end market doesn't care for your digital amp and digital dsp stuffs stuffing into a speaker with drivers bought from China OK.  Have you never bought any high end stuffs before?  Can't you tell the difference between a $7K amp and some cheap digital make in China amp?

I am not going to use any stinking digital with my high end drivers bought from Seas or ScanSpeak or Accuton.  It's like taking Ms. Kate Upton to McDonalds OK !!!

What am I going to do with my $5K vinyl table?  Ain't no stinking ADC will touch it lols.

How about my $7K McIntosh tube amps?  Ain't none gonna fit into the back of the digital speakers.  The heat alone will burn up your speakers.

So why don't we put all these digital nonsense stuffs to rest.  Maybe there's a "Made in China" forum where you can go to make your case there :-)


Posted without comment:

With just over a month left until its global debut, pre-orders for the Porsche Taycan electric sportscar – which it is understood will be released in three variants – have surged to 30,000.

This is 50% more than Porsche’s original first year target run of 20,000 Taycans, and more than the entire number of reservations for fellow automaker Volkswagen’s electric ID3 hatchback (the latest count from VW sales and marketing boss Jurgen Stackmann in mid-July being 22,000).

The numbers, which no doubt justify the German premium carmaker’s decision to double its first year production run to 40,000 in January, were confirmed by Porsche’s HR director Andreas Haffner at an event in Zuffenhausen, as reported by German news site Handelsblatt on Sunday (Euro time).


Ferrari just launched Its most powerful street-legal car ever — a 986 horsepower road bullet with three electric motors.

The SF90 Stradale marks Ferrari’s first plug-in hybrid that’s not built for the racetrack. It’s powered by a 4.0-liter turbocharged V8 that generates 769 horsepower, but gets another 217 horsepower from three electric motors — one powering the rear wheels and two for the front.


Let's also not forget the P100D is the fastest accelerating production cars till at least 60mph, and the P90 not far off, so essentially supercars. There are a lot of them out there.



andy2 OP688 posts10-30-2019 10:34pm
High end expensive stuff from companies with sufficient depth to design and program signal processing electronics, i.e. like Harman companies, are doing high end in digital.

That’s not I see in REAL life. Most of the most expensive speakers on the market are analog. I can only speak with real life examples. Sure with imagination anything is possible. There are a few digital stuffs but they are few and far in between and hi-end market does not take them seriously. Like Ferrari or Porsche or Lamborghini, nobody wants to drive an electric supercar.

Real life statistics: what is the percentage of speakers sold here on Audiogon that are digital?  It can't get more real than that.
For what it is worth:
The genetic difference between chimpanzees and man is 1%. Any two random humans differ by less then 0.1% genetically.
 Message: Small differences matter.
In my experience, time/phase coherent  speakers reproduce for example the applause of the audience in a life-like manner. Depending on the recording technique, they reproduce a space better.
Inches matter. The distance between your ears or time difference of the arrival of a sound is what allows to localize the origin of a sound. Say that’s 6 inches or ~ 16 cm. Some may have bigger heads.
1 cm doesn’t matter? Think again.