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Only a handful of speakers made today come close to being physically "time coincident" (defined as having all drivers in the same polarity with individual driver responses arriving at the ears at the same time, sometimes called "time/phase coherent"). AFAIK: Thiel, Tannoy, Green Mountain Audio, Dunlavy, Vandersteen, Quad, and a few others are the only ones that employ what might be considered as, or something close to being "time coincident". Do you own or wish to own a set of speakers from one of those distinguished brands?NOTE: Some would argue that it is not necessary for a multi-way speaker to have all drivers in identical polarity IN ORDER FOR ALL DRIVERS TO BE PERCEIVED AS BEING TIME COINCIDENT. But please, lets try to forget about that argument for now. If it is possible for you to ignore that argument, I would be very interested in finding out how many of you own (or would prefer to own) speakers from manufacturers like those listed above.
Some of you might own or prefer speakers that are not truly "time coincident" because they display unique characteristics that appeal to you more. Maybe you feel that other aspects of speaker performance (dynamics, dispersion characteristics, timbral accuracy, etc...) seem to become compromised in the quest for "perfect driver polarity". So, feel free to explain why you might choose to ignore "coincident" designs in favor of another type of design.
Edits: 09/04/14 09/04/14 09/04/14 09/04/14 09/04/14 09/06/14Follow Ups:
2-way spheres.
Warmest
Tim Bailey
Skeptical Measurer & Audio Scrounger
did you mention vandersteen?
i'm specifically a fan of sealed and acoustic suspension speakers, but also put time aligned drivers high on my priority list. i still wouldn't mind owning a pair of infinity modulus 5 1/2" 2 ways with emit tweeters circa 1992 or so. those were my idea of "the ideal speakers" for the longest time as infinity was the brand that got me into hifo to begin with when i heard a pair of their 4 1/2" 2 ways with polycell tweeters and was amazed by the bass CLARITY and speed they had compared to slower and boomier sounding full sized speakers.
back when they were still sealed, i lusted after wilson watt puppys for being sealed and time aligned.
i really liked the sound i heard from a pair of magnepan MG12s once on a tube amp, but haven't like the sound of larger maggies that can have either an aluminum foil pinging sound or an even more annoying gritty sound like the last pair i auditioned that made dark side of the moon's vocals sound unbearable.
so for now, i have my heart set on getting a pair of KEF LS50 2 ways as they have solid cabinets with nicely radiused front baffles and 5 1/4" coaxial drivers that should image like crazy. they're class A rated by stereophile and "only" $1,500 a pair. once the ports are plugged, they should be able to easily beat all of the speakers i've bought to try and have NHT superzero imaging and lack of resonance sound but with higher resolution, but sadly, energy RC10, mission M71 and celestion ditton 100 all have annoying box resonances that the KEFs shouldn't.
every review i've read for LS50s has been favorable. i've never been a fan of the brand as they almost exclusively make ported speakers, even bandpass *cringe*, but if they provide port plugs for them, then they should offer the sealed mini sound i'm after with even higher resolution and lower cabinet resonance than i've been able to find so far.
that copper color is kind of fugly, but you can't have everything.
BTW... B&W stopped time aligning it's tweeters on it's 800 series. i guess they value dispersion/lack of diffraction over time alignment these days.
If it's ported, it's distorted.
d
Edits: 05/31/15 05/31/15 07/06/15
My understanding is that it is relatively simple to time align speakers by either steping back the midrange from the bass speakers then stepping back the treble from the midrange or achieved by a properly designed crossover electrically doing the same thing. Phase coherency is harder to achieve and is realized at a particular distance from the speakers. Not quite a "head in a vice" distance but limited nonetheless.
?
Warmest
Tim Bailey
Skeptical Measurer & Audio Scrounger
The crossover appears to be 2nd order acoustic, but they put the WOOFER in negative polarity and not the tweeter. This gives in *initial* positive going impulse response.
I now wonder about this "putting the woofer negative instead of the tweeter" for 2nd order designs requiring a polarity flip...
I wonder how this would play out sonically...
HMMMMM.
Copper color will grow on you. I have WMTMW's with Vifa MG10MD0908 fiberglass-cone mids and they are quite an ugly yellow color. You get used to it.
Cheers,
Presto
Assuming that one is able to detect mixed polarity in a multi-driver array, how would the entirety of the signal be perceived if only the initial "attack" phase of the signal is unified in polarity?
That is the question of the hour.
But since it's just the antithesis of the "2nd order with inverted tweeter" it *may* only be an absolute polarity discussion.
Or, due to the way we perceived sound, may not be.
I'm just asking the questions here because although I understand the theory (to an extent, with some practical experience) my own "jury is still out" on the entire subject of absolute polarity.
Even a 'transient accurate' 4th order compared to a "phase mangled" 4th order (with 4th order group delay) is not a "day/night" sonic scenario as many want to believe. I've listen to both scenarios *through the exact same speakers* with nothing else changing but the group delay correction. After doing many "on/off" comparisons, I gotta say... after believing it to be a panacea when I got into the subject, I now believe for some it may not be a big deal and for others it's not a concern at all.
To this day I still wonder to what extent my mind is telling me I hear better sound when I am visualizing the measured response in my head.
That near-perfect parallax impulse with almost zero over-shoot...
Mentally, these images are very powerful for audiophiles, especially someone who takes measurements and makes corollary with the sound. The human brain seeking corollary and explanation can often be as much of a hindrance as it is a help.
Cheers,
Presto
It is said that the initial attack of a sound is the thing that helps us to identify it's true character or nature. The proponents of time-coherent loudspeakers seem to believe that, unless all drivers are polarity matched, the leading edges or the "attack" phase of sound becomes smeared. This, in turn, is said to create a loss of natural sounding detail among other things.
Could it be that KEF was simply trying to create a happy compromise between amplitude response, good dispersion characteristics, and time coherency in the LS50 by using the method described by you above?
This is a pretty complex problem, not easily resolved by just mounting drivers on a sloped/stepped baffle. I was talking to a who guy designs speakers for a living, and he said what's really important is that both drivers are in phase *at the crossover point*, as that's where it's most notable. Of course, a driver's phase will vary as function of frequency, so getting this just right can be a bit tricky.As others have stated, phase coherency is nice, all things being equal. But I'd prefer a speaker that didn't have a mid-bass suckout or glaring highs (but wasn't phase coherent) over one that did have those issues but was phase coherent.
It's just one part of the recipe.
Edits: 09/11/14
Yes, it would seem to be just that...Roy Johnson of Green Mountain Audio claims that creating a truly "time-coherent" loudspeaker involves some pretty incredible mathematics and engineering feats and that some manufacturers don't want to bother with the complexity of the situation. I certainly have nothing against time-coherent speakers but I'm pretty sure that half-assed implementations may not be worth the extra trouble and expense.
Edits: 09/09/14
Have modded TC-50s now, and planning on a pair of Vandy Quatros when I leave city apartment life in a few years.
WW
"A man need merely light the filaments of his receiving set and the world's greatest artists will perform for him." Alfred N. Goldsmith, RCA, 1922
WW-
On several different auditions, I tried to get into and like the Quattro.
Still, I have not been able to do so? I have heard these speakers w/ Ayre, Mark Levinson, Clase' and Aesthetix gear. They just do not jive well w/ my ears? Perhaps, you have had a better demo than me?
A friend has a pair with cj Premier 12s and they are quite lovely. I hear a little bump around, I'd guess, 5-7k. It isn't enough to detract from orchestral work, but is enough to give a little edge to rock, which is something my polite Spicas can't do.
WW
"A man need merely light the filaments of his receiving set and the world's greatest artists will perform for him." Alfred N. Goldsmith, RCA, 1922
WW-
what other gear is in your friend's system?
His other gear: some monstrously big gold-colored Sony SACD player from some years back, and a VTL Super Deluxe pre as a line stage. (Yes, it's a shame to waste the phono stage from that.) I forget what cables he has. No vinyl - he gave me his LPs when he moved to Argentina. Donno what happened to the LP-12/ET-2 combo. He probably has 10-15,000 CDs and SACDs. His disc shelves take up about 8 x 10 feet completely filled *without* jewel cases. When I visit next we'll try to figure out just how many little silver discs he's got.
WW
"A man need merely light the filaments of his receiving set and the world's greatest artists will perform for him." Alfred N. Goldsmith, RCA, 1922
WW-
very interesting combo of gear. When you can ask him about cables/cords do so, as they will tie everything together nicely. Would love to see that CD/SACD collection...
I am not well versed in speaker technology and tend to like older designs. Among my 5-6 pair of speakers, I keep the time aligned, phase coherent, ported Meadowlark Blue Heron II in my main system, because, they just sound right.
I know Meadowlark went out of business 9 years ago, but Pat McGinty is still spoken of fondly at recent audio shows I have attended, and his 1st order crossovers seem as honest today as many of the more exotic designs. I cannot intelligently discuss the engineering or acoustic niceties of this speaker, but the detailed, musical sound is completely non-fatiguing. If these attributes are due to time alignment/coherency, punch my ticket and I'll stay on board.
I have Vandersteen 5A's and sometimes with the right recording, its spookily real.
The Vandersteen Quattro, 3A Signature, 2CE Signature, VSM, VCC-1, and VLR have all served in my systems over the years and have good performace compared to the competition. Phase coherence is typically limited to a small listening window in most of dynamic loudspeakers mentioned in this thread, and the sound quality of the Vandersteens and others may relate more to smooth tonal character than time and phase coherence.
A few loudspeakers offering time and phase coherence that might go unnoticed by most audiophiles are the DIY Sound Group Fusion-8 Alchemy and the Danley Synergy horns. Both are very interesting designs offering good performance at very different price points and serving completely different segments of the market.
I have found that time coherence lends itself to smoother response perception. I found this to be true whether it is a multi-driver or single driver setup. My Acoustats had a very flat in-room FR and were utterly relaxing to listen too. The same goes for my Ref 3as despite the worse measurements in-room. I think the perception of a well integrated and treble and smooth overall sound. It is more natural than a scrambled signal.
My limited exposure to time/phase coherent speakers suggests the same thing. I'm not sure that they sound more realistic than less coherent speakers but they do seem to be very "listenable".
I do. I endorse both of Thiel CS 2.4 or CS 2.7 models. These are my reference loudspeakers.
I have a feeling the CS2.7 sounds very nice and probably just about the same as the CS3.7. When I bought my CS3.7, the CS2.7 was just being introduced. I'm sure I would have been just as happy with the CS2.7 because the main thing I wanted was that special coaxial midrange/tweeter, which was only available on the CS3.7 before the introduction of the CS2.7.
Best regards,
John Elison
Right On! JE.
the major difference between the 2.7 & 3.7 is that the 3.7 requires a much bigger room to really open up (20x20, 25x25, 30x30...etc.).
THey use a 2nd order crossover and so by definition are phase shifted in such a way that the highs cannot reach the ears at the same time. Kef and a few others that put the tweeter in the throat of the main driver are also not time coherent.
Also, you forgot these speakers
Acoustat
Soundlab
Audiostatic
Other full-range electrostats
Full range single driver speakers like Lowthers etc.
Reference 3a
Spica (at least the TC50s were I believe)
Read this..
Yes, the drivers are in the right place to be time coherent BUT the crossover is not right. Look at these measurements from STereophile:
http://www.stereophile.com/content/tannoy-churchill-loudspeaker-measurements-part-2
http://www.stereophile.com/content/tannoy-dimension-td12-loudspeaker-measurements
http://www.troelsgravesen.dk/tannoyMG15.htm
The blurb from Tannoy is misleading and if they are implying time coherence they are lying. Stereophile's (and other's) measurements are clear indication that the two drivers are not coherent.
I guess we really don't know what we've got until it's been measured!
BTW, I seem to remember reading that a fair number of manufacturers make the claim that their speakers are "time-aligned" and/or "phase-coherent" when they are not truly so. I wish I could remember where I read this, but right now the memory escapes me...
Well Dynaudio claimed phase accuracy in their designs because the used 1st order xovers supposedly (don't know about now) but they were never time aligned because the baffle was flat and not sloped to compensate the distance to the listeners ears.
It could be that the only way to know for sure if a speaker is *effectively* coherent is to take some measurements. For example, it was assumed (by some here) that a speaker like the Wilson Alexia could not be "coherent". But, as John Atkinson replied:"If you look at the step response in my Alexia review, you will see that the output from all the speaker's drive units arrive at the ear WITHIN THE BRAIN"S TEMPORAL FUSION WINDOW, ie, those arrivals WILL NOT BE DISCERNED AS SEPARATE EVENTS... If you think you can hear these SEPARATE ARRIVALS, you are actually hearing some other aspect of the speaker's behavior."
There is a "window of opportunity", so to speak. That's why I'm not sure if the Tannoy's measured behavior would reveal something similar to the above. Maybe you can speculate on the possibilities?
Actual reality can be confusing because it sometimes conflicts with theoretical reality. That much I do know.
Edits: 09/06/14 09/09/14
The Alexia is not time coherent either, in fact one driver is going out while the other is going in (inverted polarity). It is far from time coherent despite the marketing BS. Compare that with a Thiel CS (any model) graph or a Vandersteen and you will see that they are world's apart.
The question of whether or not it is audible is the age old question and at least some of us are quite sensitive to speakers being coherent. My Ref 3as make a quite nice triangle and are clearly time coherent from measurements.
It is whether or not the speaker could make a credible and visually recognizable square wave as Quad used to demonstrate. Most speakers make it look like complete garbage and it is on the forgiving nature of our auditory system that allows non-coherent speakers to work properly at all.
The biggest advantage I have usually heard from coherent speakers is a much better integrated treble that seems smoother and less prominent. This leads to a more natural feel for the sounds in general as well as soundstage and imaging naturalness. This also leads to a lower fatigue factor...maybe the brain is just not working so hard to "decode" the sound waves projected its way?
What I can't understand is why Tannoy doesn't try to make drivers to use a true 1st order xover so that they can take ultimate advantage of the coincident driver concept.
The Ref 3as don't use a crossover at all on their main driver so it is possible but it has to be part of the design priority.
I would say that Tannoy is one of the most coherent sounding speakers that are not time aligned. To get them time-aligned would require a serious driver redesign though.
Despite the fact that the Alexia has one driver inverting, the ear perceives all drivers as being "time-coherent" when heard from several feet away at the recommended listening position. That is my interpretation of Atkinson's words.
Not time-coherent. I don't agree with your interpretation of JA's words. You have to think about group delay as well as phase. The order of the crossover affects both phase shift and group delay. That is why a 4th order LR crossover can be in phase but not really time coherent because the phase rotation delays the wave propagation. The Alexia even inverts polarity.
"This graph reveals that, as in the Alexandria XLF, the tweeter is connected in positive acoustic polarity, the midrange driver in negative polarity. However, with the tweeter module set up by Peter McGrath, the graph also shows that the negative-going decay of the tweeter's step smoothly blends with the negative-going start of the midrange unit's step, confirming the excellent frequency-domain integration of their outputs seen in fig.4. "
JA doesn't mention time coherence at all. He talks about frequency domain integration.
Check out square waves from the Thiel CS5
http://www.stereophile.com/content/thiel-cs5-loudspeaker-measurements-0
Not as good as the Quad 63 but not bad all the same.
.., "... the output from all the speakers drive units ARRIVE at the ear" and "the brain's temporal fusion window", etc.., would seem to be related to TIME domain behavior. That's the conclusion I was able to draw after reading the quotation in the post above.Thanks for your helpful input.
Edits: 09/09/14 09/09/14
The measurements clearly show that this speaker is like the vast majority of speakers reviewed. NOT TIME or PHASE coherent.
The reviewers words are trying to imply with separate facts a different fact that actually is not a fact.
Not saying the speaker in question is bad or the review is invalid, but it does not qualify as a type of topology that your original post was targeted against.
Well, you seem to be pretty sure about all of the above so I guess I'm willing to let the subject go for now.I would try emailing John Atkinson to ask him if he'd care to chime in but because his responses are so often met with hostility around here, I doubt that he'd feel like responding one more time.
BTW, my original post was not "targeted against" anything or anyone in particular. I'm taking a poll, that's all...
Edits: 09/09/14
. . . was a pair of Audio Concepts S2Rs, designed by Mike Dzurko. This design featured a "time coherent" tilted-back baffle (about 15 degrees tilt) with Vifa drivers and a first order crossover. They sounded quite nice, but best on a VERY narrow vertical listening axis. Obvious lobing issues appeared above and below this axis, due to the shallow crossover slopes, and of course they were no longer "time coherent" off this axis. I cannot honestly say that they sounded significantly better than good non-TA designs I have heard with similar drivers and steeper crossover slopes.
I think good phase tracking through the crossover region is more important and audible than absolute time coherence. This can be achieved, on a conventional vertical baffle, by making the highpass filter an order or two steeper than the lowpass, to add sufficient phase lag to the tweeter when its acoustic center is physically forward of that of the midbass.
time coherency can only be achieved at a particular direction of radiation.. all other radiation is not time or phase coherent. I've enjoyed time coherent loudspeakers - from the lowly Boston A40 - tweeters at the bottom on a 20" stand. to Vandy 2Ce. My current Magneplanar MMGs ar time coherent at my ear position. with DSP active crossovers it is easy to to time align just about any system.Does it sound better? heck I don't really know... if I move my head a bit fowrad or back or stand instead of sit - the time coherency is lost - but the loudspeakers still make a convincing image.
I've enjoyed many a non-time coherent loudspeaker, from Obelisks to B&W's. Toole discounted the need for time coherence against other parameters. Heyser thought it an admirable goal - though impractical. In professional systems - time alignment greatly enhances performance.
Most recordings are not produced in a way to maintain time coherency - at least relative to a live event. I am a big fan of M-S recording technique that, at least in a broad middle frequency range, maintains time coherency - allowing the signals to be placed in some kind of a produced sound field.
"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius
Edits: 09/08/14
All things being equal, of course. But then all things are never equal. I don't really think there are drivers available that with ^ Db/octave slopes won't be so far into their bad regions that the trade off of time coherence will make up for that. It's a way too complex subject to ask such a simple question about just one factor in sound reproduction.
True, but people do love surveys and polls with simple questions.
> I don't really think there are drivers available that with ^ Db/octave slopes won't be
> so far into their bad regions that the trade off of time coherence will make up for that.Jim Thiel designed his own drivers to accomplish that task. I think they work exceedingly well with 6-dB per octave crossover slopes.
.....
Edits: 09/05/14
I'm coming to think that there's more than one way to skin the speaker design cat and one particular factor (time coherence, for example) doesn't tell you the whole story. That said, I find the time-coherence-as-holy-grail idea very appealing because of all the sonic benefits that "should" theoretically accrue as a result. Yet, I didn't keep the pair of Green Mountain Audio Rio's that I bought a few years ago because they just didn't do it for me the way I thought they would. (I hasten to add that Roy Johnson of GMA is a heck of a good guy who sincerely believes in his approach to speaker design, and that the Rio has since been upgraded to the "Chroma" which has a revised crossover design, so maybe I'd react differently now...)
Personally, I've found speaker happiness with my Reference 3A Dulcets and, since upgrading, De Capo BE's. Only a single capacitor on the tweet and the main driver driven directly by the amp, along with a slanted baffle and offset tweeter to facilitate better time alignment. I don't think Reference 3A claims that their designs are completely time coherent, but they image like crazy and sound really coherent. Go figure.
Rebbi,Thank you for your kind comments.
Since your post will be on the internet forever, I wanted to leave a useful response here. I hope all is well with you and yours!
If you and I agree that a speaker's design and a room's acoustics are both responsible for what is heard from any speaker, then it is important readers here know about your very unusual listening room setup when you tried our Rio speakers. This is NOT meant as criticism, please. Instead, I hope everyone sees an educational value to the following:
You formed your opinions when listening in
-a small, bare-walled bedroom,
-the speakers hard up against the wall behind them,
-a nearly-bare window in between,
-a table directly next to, and well out in front of, one speaker,
-you sitting upright on your guest bed
-with your head against the wall behind,
-the speakers ~2 feet from the foot of the bed,
-your legs stretched out in front of you.You sent me photos for acoustic-treatment suggestions; none were implemented at that time.
And I agree this was still far better than having no tunes in there at all!Yet, since you do not indicate otherwise, anyone would expect you to have been in
-a medium-size or larger living room
-having little echo,
-with your speakers pulled out from the wall and video screen,
-away from sidewalls by several feet,
-with carpet between you and the speakers,
-no large coffee table (= your bed here) in front of you, and
-your head well-away from a wall behind.Rebbi, please know that I think this in no way undermines your choice of another brand of speakers for use in this room.
However, to those people looking up what time-coherent sound is all about, two aspects of your unique experience are worth illuminating:
-A non-time-coherent speaker, as you ultimately chose, makes less-coherent reflections off walls and surfaces, by definition. This incoherence in your many really, really-early reflections softens their effects by removing some of their 'directness', literally some of their 'immediacy' that attracts attention.
-When you told me those other speakers were more musical, I am sure I would have heard that too. I reminded you that you did not own our speakers long enough to break them in, to loosen them up mechanically. This affects what anyone would call musicality.
Thank you for reading this through. Again, no criticism was intended and I am not looking for any reply.Let me know, Rebbi, if I can ever be of service about anything. Always enjoyed our time together! Call to visit anytime.
Best regards,
Roy Johnson
Green Mountain Audio
Edits: 05/30/15
I'm sorry to hear that your speakers did not get the careful attention in setup that they surely deserved.
Thanks, it happens. In this situation Rebbi had no choice, and I understand.
The lesson I take is "More photos of members' setups, please."
Perhaps as a Requirement of Membership, with written descriptions too.
These tell us much about why and how someone heard 'whatever'.
Imagine never knowing what music someone played to form those
"very strong, well-worded, and seemingly knowledgeable" opinions.
Not knowing anything of his physical setup and acoustics leaves us equally blind.
Cheers,
Roy
Once you live with Time Aligned speakers others seem false
Very nice you could get the gear off to the side, and not in the middle. Thumbs up! Ears forward!
Roy
I'd like to hear Ref speakers someday.
I own a pair of Theil CS 2.2-BTW the CS stands for Coherent Source-fantastic speakers-
I've included a Stereophile link to an interview by Jim Theil regarding his CS speaker line.
http://www.stereophile.com/interviews/221/
I added Thiel.
Make that Thiel-nt
I use them
Done.
my life experience proved to me that they [all] imaged better (fidelity/response is subjective) but it hasn't. Most of those you mentioned image quite well but I have heard others that do all kinds of weird things with phase and xover design that image as well or even better.
ET
.
Think you maybe confused what time arrival means and what designs can be time aligned more than at one spot in space. Also a loudspeaker is a total design involving compromises and many variables designers work with such to get end result.
Some of these terms can be confusing, so...
Correct me if I'm wrong, but my understanding is that a "time coincident" (origin unknown) speaker is one that basically "time/phase correct" (Vandersteen).
And, correct me if I'm wrong (again), but the typical "time/phase correct" multi-way speaker is both time-aligned and phase coherent, typically for a narrrow listening window or point in space (ear height at listening seat), and strives to keep all drivers operating in identical polarity.
Having all drivers operating in identical polarity is a big thing for some people, who claim that mixing up inverting and non-inverting drivers in a multi-way speaker inevitably prevents the reproduction of a natural or realistic sounding waveform.
Does all of the above sound correct to you?
I bought a pair of Thiel CS3.7 speakers, which are advertized as "time-coincident" or "linear phase" to ±10-degrees. I don't know how true that is, but these are the best sounding speakers I've ever owned and I am completely happy with them. I have owned them nearly two years and I have absolutely no desire to replace them.
JE,
which cross-over order is used in the CS 3.7?
I prefer Thiel as a reference loudspeaker over Vandy and Aerial.
The CS3.7 is specified to contain only 6-dB per octave crossovers.
As a long term coherency freak, I prefer single driver designs with uniform directivity. Just not from a box.
Tried for a while to go back to non-coherent speakers...couldn't stay there. Don't have big stat panels anymore but coherent monitors (Ref 3a).
I have experimental / prototype WMTMW 3-way speakers that use computer based FIR and IIR crossovers. The IIR crossover is "phase correctable" with a 'forward-reverse' type phase processing. (This results in a latency delay, meaning that I can't use the speakers in this mode for video unless special equipment is used to delay (re-synch) the video.I have measured not just the output of the crossover, but the acoustic output of the system, and indeed, I get phase-coherent (transient accurate) reproduction.
The nicest part of this is that the phase correction component can be quickly and simply switched off - push of a button.
In my honest opinion - I don't think T.A. performance is a deal breaker for me. I also think that people who swear by TA speakers might be liking something ELSE about the speaker... it's possible. They believe they like the speaker because it's TA. I think people can like a speaker because it's blue and someone said blue speakers sound better. Yes, gasp gasp, some will vehemently disagree. But I can switch back and forth between measurable TA and non-TA performance and for me, there are quite a number of metrics I would not sacrifice just to get TA performance.
That said, in my case, I leave it on out of principle because, well, why add phase distortion if you don't need to.
I am willing to admit I am "doing it wrong" or "not doing it best", but my measurements tell me that I am doing it right so I have no reason to think I've done it wrong.
I just don't think that BY ITSELF it's a vital necessity for engaging and enjoyable sound. If anything, I think a 1st order acoustic passive design that is TA might just have too many (40+?) components and suck certain aspects out of the music trying to get too many impedance, phase and amplitude response anomalies corrected to achieve the 1st order acoustic response. People who like crossoverless mids and caps on tweeters might agree with me here.
Some might say my system is doomed because it uses DSP-based crossovers. To that I say: You surely may be right. In fact, everybody may be right - I have a rare belief about audio now. I believe everybody is correct when they say something about audio based on what they like.
I like TA 1st order acoustic designs. They sound better.
I like full-rangers with supertweets. They sound better.
I like horns with flea amps. They sound better.
I like panels because they are inherently TA. They sound better.
I like DSP or outboard/active crossover solutions. The sound better.
I like blue speakers they sound better.All guys are correct if they've put the time into their systems and listened to them.
There is no panacea.
Did you enjoy putting your system together?
Do you listen to lots of music and do you gets lost of goose bumps?
Do you rush to the audio room when you get home from work?If you said yes to these questions, your system is awesome FOR YOU whether it is TA or not, has low bass or not, has "good" lobing tilt or power response or not.
That's my philosophy these days, which is why I seldom argue on here anymore.
Cheers,
Presto
Edits: 09/04/14
Much wisdom, here.
.
My Reference 3A Grand Veenas are both in phase and time aligned. I discovered the advantages of such designs after I bought a pair of Dunlavy SC IVs after owning a several well regarded speakers. Now I wouldnt own anything else.
.
...are phase and time coherant.
The beauty of first order crossovers, a sloped baffle and concentric drivers.
To be clear, acoustic phase as described by Heyser is the bottom line so far as “time”, that measurement describes the acoustic output relative to the input signal.
VERY few multi-way hifi speakers radiate as if they were a single driver in time and space. While DSP can correct time, it can only do so for one set of path lengths to the listener as having drivers that are too far apart to combine coherently, means they radiate independently as seen by a pattern of lobes and nulls in their vertical and/or horizontal polar patterns. While two or more sources can add coherently, the distance between them has to be a quarter wavelength or less at the highest frequency of interest.
The larger a loudspeaker system becomes, the more audible this problem becomes and is why large scale sound generally is very dismal especially with large arrays which radiate from many locations in space and so also in time. The interference pattern they create is complex and so if the wind blows, that becomes very audible as well.
In the small scale like home hifi, the advantage to a simple single point of radiation is that the location of the loudspeaker in depth is not obvious. In stereo, that means that when playing a mono signal (same signal to both speakers) that one hears a solid phantom image in the center and you DO NOT hear the right and left source.
Speakers that radiate from different locations produce an interference pattern produce a mono phantom image but also have an obvious right and left source as well.
Arrays of many drivers often produce a much less solid mono phantom image but produce more like a ‘wall of sound” as what arrives at ones ears is comprised of many individual arrivals in time according to the path lengths differences from each source.
As a result of the electrical signal representing “one point” in time and space, speakers which radiate that way tend to have the best reproduction of the recorded stereo image, speakers which have directivity and the latter property, tend to have the largest near field and most faithful stereo image.
How about these:- Tannoy Dual Concentric
- Dunlavy
- Quad
- Vandersteen
- Thiel
- Martin Logan fullrange models
- Sound labs fullrange models
- Single-driver systems
- Ryan
- Danley
If these brands or types do not qualify as "time/phase coherent", what can we say about those who claim to hear "THE DIFFERENCE"?
Edits: 09/04/14 09/04/14 09/04/14
Full range electrostatics like Martin logan, Sound labs do radiate from a single point in time although may produce somewhat of an interference pattern due to their physical size, the Quad esl63 radiates like a single point in space and time, most full range multiway loudspeakers do not radiate from one point in space because the drivers (where they interact) are too far apart to add coherently (into one new source).
A first order crossover is the only passive crossover of the ”named variety” that sums without an overall “all pass” phase shift.
A single small full range driver mounted to a large flat baffle can be VERY good in this regard. There is no “all pass” phase shift crossovers above first order crossovers produce, no significant secondary radiation from cabinet edges but they do have other limitations.
The spherical segment radiation of a quad ESL-63 was part of the inspiration for the Synergy horn (Danley) and many of these do act / measure / sound like a single crossover-less driver with constant directivity and the earlier Unity horns radiated like a single driver with some degree of crossover phase shift.
Best,
Tom Danley
Though, I believe Duntech is still producing loudspeakers, Dunlavy Audio Labs ceased to exist quite some time ago. Sadly, John Dunlavy also ceased to exist back in 2007...
Own two pair of Dunlavy's. Hope they never crap out because I love them.
See ya. Dave
and previously used Thiel 1.6s. Both sound great and are exceptional value for the money (especially the Vandies).
But I don't think it's necessary to have time coincident drivers to get great sound. The very best speakers I've heard are: Vandersteen 7, TAD Ref One, and Vivid Giya. One has time coincident drivers, one has a concentric driver for the treble and mid-band (but is not time coincident), and the other has neither technology (but has the drivers connected with positive polarity). All designs have trade-offs and great results can be had using different approaches.
Nicely detailed but relaxing presentation. My speakers use time/phase alignment to deliver a relaxed presentation reminiscent of the Vandersteens.
Interestingly, my limited experience with speakers of this type tells me that *time/phase alignment* does not offer any real increase in the sense of "realism" I get from loudspeakers. I'd say that time/phase alignment simply provides a very relaxed and "listenable" presentation, but not necessarily a more realistic one.
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