Oh, BTW...Happy Halloween. Greet the kiddies w/15hz. *L*
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 ... :-)
Showing 27 responses by asvjerry
@geoffkait , @tomic601 , big *S*...one of my faves too. But we surely need more coherent heroes of late, and that's about as much as I'll go into That... Re 'electric supercars': Lotus Evija...and let's watch what Formula E does for the breed. And most of today's cars owe a lot to superbikes and the racing of.... ;) For once I'm enjoying this forum, since I'm on the verge of wading into these weeds with my DIY endeavour. Since IMHO I'm a long-standing skeptic of the 'perceived' vs. 'measured', analog vs.digital, this X vs. Z 'enhancement' to the audio experience, a 'lively discussion' of the subject at keyboard is appreciated by y'all. *S* Please, carry on...and play nice, 'K? ;) Or I'll sic the Watchmen on y'all...*L* (Oh, FYI...have a Behringer DCX2496 to play with. Yup, digital domain domination...) |
@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... ;) |
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* ;) |
@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....) |
@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? |
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... |
@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'. |
...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... |
@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...;) |
@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... |
"...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] |
Sorry, @andy2 . My excuse is that I 'was born this way'. If you haven't run into a 'personality type' of my sort, that's not my problem. If you'd care to note the time this post has been made, it's a bit early for even my lifestyle to get fried enough to 'drunk post' this early in the day. As is said, "It takes a lot of souls to fill a freeway." And, having been born in SoCal (Long Beach) some 68 years ago, I might be able to legitimately claim the effects of smog causing mental dismangement.... But I won't. As for the way I express myself; if you'd prefer monosyllabic retorts....not very likely from this mortal. 'Short & terse' isn't really my style, here or IRL. Besides, this is really 'off-topic', you Are the 'OP', so...get back to it. No apology sought or required. Have a good week. |
[lurk disengaged} @andy2 ....I won't disagree with you as to the 12:51 pm 11/3 post; all of which is generally acceptable. As for your personal hearing range, lucky you. *S* As for how you can discern that I'm drunk or under some sort of influence over and through this medium that we're engaged in....*hmm* That will take a certain amount of explanation on your part to the viewers of this forum as to how you've arrived at that observation. I'll leave that issue for you to explain to the viewers here. Personally, I've been called worse. How far you care to sink is your call. |
Most of the better systems I've been around are such. It makes sense to cope with the signal on a lower level before adding 'power'. Better and more discrete control without having to cope with high drive levels. The same holds for active eq; I can 'adjust' for my space, even with omnis. I can 'ignore the room' so to speak, since I'm in the midst of it. I know I'm ignoring most of the past posts...but I'd rather cut to the chase. MHO.....and please, 'humble' is the word of the day....well, this evening here. *G* |
@ivan_nosnibor ...there's a lot of it going around of late. :( @andy2 ....here, from 20:30 on...try to get the picture. I'm not drunk....just... Oh, 'ell....it's Friday. Try to have a nice weekend, huh? https://www.youtube.com/watch?v=RQeOm3CuUFY |
...and I'm now quite happy to be on the other side of the country... *G* Anyway...calm down, stay on topic.... I came back 'cuz you started a topic that got my interest, and that of others. I/we don't mean to make you feel attacked, far from it. Phase issues, which you yourself stated earlier are complicated. Resorting to 'quantum states' ain't gonna help us typical audioholics, no. I'll return to my last aside that active xovers may cure the bulk of the issues. Give the drivers what they Need 'upfront', so to speak. Yes, it requires bi-, tri-, or whatever amping quantities required... ....but it sure works in my space.... Just saying.... Don't shoot. ...please? |