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* JM Lab is time coherent but not phase coherent.
* German make "Manger" is a single driver speaker & by its very nature is time & phase coherent.
* Taiwanese make "Usher" appears to be time-coherent esp. from the looks of their floor standing speakers' sloped baffle. Looks could be deceiving tho' - I have never heard this brand.
The new Triangle tweeters were developed as a semi horn design to address this issue in a more conventional cabinet.
My Coincident Digital Masters are time coherent, but Israel has gone to more conventional cabinet designs in his recent efforts to ease manufacture and lower costs.
Reference 3A speakers claim time coherence.
My friend Michael's (Sufentanil) Audio Physics speakers are time coherent.
The Fried Valhallas (C Series monitors) were time coherent, and we are probably going to introduce a C7 monitor next year. The pair we are using as our reference to the old days can really play tricks on your ears, they're flat out wicked! I once SWORE a phone was ringing behind me(and I was sitting against a wall), and it was the music - speakers were 15 feet in front of me.
But, overall, I think your premise seems to hold water. It's an interesting point, thanks for raising it.
That's a very good question. The british speakers seem to be more interested in smooth frequency response, than time and phase. To date I haven't heard a british speaker that images particularly well (and don't say ls3/5 because they don't image at all !)
As a brit myself I find my compatriots' fascination with this thing called PRAT to be a bit odd. Why are we so quick to throw out spatial information to try to make the music bouncy ? Perhaps because fewer brits have the space in their houses to allow for speaker positioning that would allow imaging ?
Bombaywalla is incorrect-JmLabs speakers are time AND phase correct. They design the structure of their speakers and their crossovers with that in mind. Don't forget that it all depends on listing distance and height of the listener relative to the loudspeaker drivers(especially the tweeter) in order to benefit from such a design.
Wilson Audio's are also correct, and are set up when you purchase them for your arrangement, but then again, they're American also.
The JM Labs are not time and phase coherent by any stretch of the imagination! Look at the step response of the Utopia, the woofer is connected in reverse polarity to the mids and tweeter. The Wilsons are not time and phase correct either. Look at the step response from the Sophia.
They're very few speakers that are time and phase correct or even just time correct.
Even if you use a single driver, this in and of itself does not mean the speaker is time correct. You can look this up in previous threads.
Vandersteen, Thiel, Meadowlark, Green Mt. and few others pass the step response test indicating time alignment.
It is hard to design these speakers and the engineering costs are high. Why do it if you can sell non-time aligned speakers and discount time as inconsequential as reported in Stereophile. If you put the Vandersteen 3a Signature in a nice wood cabinet, it would sell for $10,000! Thiel does and look at their cost.
Time speaks of when a sound leaves a driver. If it is not a first order crossover design, then it is not going to be time aligned.
Why do some companies discount it? My guess is because time and phase correctness and first order crossovers place constraints on the drivers (must operate in much larger ranges) and this can lead to reducing the power handling and dynamics of the speakers.
How many times have you heard of a spica or dunlavy owner blowing a tweeter ... quite a few. My guess is that it's not unrelated to the coherency of the speakers. How many time aligned speakers produce good solid bass ?
I prefer accurate to loud so it's a trade-off I can live with. Plus by adding a powered sub I lose coherency only in the lower octaves, where it doesn't matter so much.
The other thought is that so many speakers are placed suboptimally for imaging (the principle benefit of coherent designs) that many owners will simply never appreciate it. I'd bet over 90% of high end speakers sold are never correctly placed in the room for optimal sound, due to ignorance, decor, WAF etc.
For example if you put my spicas close up to the rear wall they sound pretty awful ... so many buyers would assume they're bad speakers. B&Ws, Harbeths, and other non-coherent speakers would probably sound much much better in that placement, leading the buyer to assume (erroneously) that they were much better speakers.
I guess what I'm saying is that the market for coherent speakers is probably narrowly focued on hifi nerds like myself, who organise the room around the stereo, rather than vice-versa. You don't get to be the size of B&W by pandering to our needs.
Sean99...well done...very articulate answer...and as a former Spica owner myself...you have good taste has well! cheers...one last note...there was a post awhile back...hell...I might have even initated it...at any rate...Joeseph from JA brought up a good point...if time/phase is that important and detectable...why do phasecorrect speakers sound different? I actually think they share more sonic traits that other speakers...that is very spatial, 3-d imaging...however...not everyone is a proponet of this sound...some prefer a more forward, "in your face" presentation...which Brit speakers(I hate to generalize) due very well...hey...I like most Brit speakers to boot...but I prefer the addictive quality of phasecoherent sound when pushed to buy....
Can someone give me an example of a speaker that images as well as or better than the spicas that is not coherent (spica's aren't coherent, but do a reasonable approximation).
Perhaps I'm completely wrong for associating imaging with phase and time coherency ? After all in the studio mixing and mastering I can't believe that all the "aural exciters", compressors, limiters etc etc are time coherent ... so the CD / LP already has phase and time errors at the source ?
I've heard it said that a narrow baffle reduces diffration and improves imaging, but the baffles on the spicas are nearly 2 feet wide around the tweeter !!
I've heard it claimed that concentric woof/tweet improves imaging, but my spicas image much much better than some kef 103/4 reference speakers that use the concentric design.
I've heard it said that small stand-mounters image better than large speakers, but the spicas just killed a borrowed pair of Spendor s3/5s in the imaging department (well in just about every department).
So what exactly does determine if the imaging thing happens ?
(My europas arrive on Friday .. I will post a review comparing them to the spicas in a month or so. I don't change equipment often, nor do I frequent shops or shows, so I can't compare more widely ... but the spica angelus sets a high benchmark for realistic live music reproduction above 100Hz.)
Oh, and I wasn't bashing B&W .. horses for courses ... I've never heard a better rendition of AC/DCs "Bullet to bite on" than through DM603s ... very grin inducing !
Sean99 good question...although the SPicas' front baffle is quite wide...it is covered in felt which greatly reduces "smearing" (which you already know)...and does come into play...along with the SPicas unique crossover network and sloped baffle...to certaintly "behave" like a phasecorrect speaker(which you already know as well!)...I believe it was marketed as such...but the mid driver does have a 4th order crossover componet...not sure...at any rate...enjoy your Europas! I am an owner as well(as are many others)...and suffice to say....I have been very pleased with my purchase...they have that "liquid midrange" presentation which few have...I have mine 4 ft from the rear wall and and about 4 ft from side walls with a listening triangle distance of 9ft...they dont quite have the recessed sound of the SPicas...but they do have improved transparency, detail and bass...as well as imaging and soundstaging that can only be described as breathtaking...tell us what you think!
Sean - here is the link to the thread I started last week.
Personally, I'm struggling with the choice between time and phase based designs and others such as Ohm, Dueval, Gallo and others that throw a much wider sweet spot at the listener. Those 360 degree despersion designs sound the same in almost any location within a room and at the same time are very accurate at imaging and have excellent dynamics. For those of us who don't have a 4 walled dedicated listening environment, it would appear a Walsh type design may be the best solution. But then again I'm not sold yet. I own Hales T-5's which are time and phase coherent and they have a pretty large sweet spot and sound damn good whether I'm standing in the kitchen or right on-axis.
It is my (admittedly very limited) understanding that electrostatics are coherent. I remember hearing some large Martin Logans at a dealer in the UK and being impressed that the soundstage was incredibly wide. However the imaging was very diffuse within the soundstage ... nowhere near as pinpoint as my spicas.
Of coure there are those that say you never get imaging so precise in real live performances ... I assume that they must only have one ear in the middle of their foreheads :-)
(Remember the joke about Davy Crockett's three ears ... left ear, right ear and wild front ear ?)
If you were to close your eyes at a live concert, you'd be surprised at how hard it is to pinpoint the position of instruments/voices. With your eyes open, however, it's quite easy. (A lot of things are easier with your eyes open.) Good imaging at home helps to make up for the lack of visual cues.
Of course, good imaging is a function of a number of factors, including the recording and speaker-room interaction, as well as the listener's own sense of what it _should_ sound like. I'd be wary of any dogmatic claims that "X" type of speaker is the best for imaging.
I've owned B&W DM604S2 for 3 years & I felt that these speakers imaged very well. I've heard many B&W speakers in DM series, N series & the now discontinued CDM series. Each time I thought that, if nothing else, the imaging was very good. Maybe your demands on imaging are far more stringent than mine??
Are you ever going to purchase a new set of speakers?? :-) I think that you have been posting on this forum for well over 1 year soliciting advice. Perhaps this has lead to analysis paralysis?? ;-)
Lastly, I 2nd what Bomarc has observed: We audiophiles put a lot of weight on imaging & maybe more than what is necessary 'cuz whenever I have been in a live concert, the imaging has never been pin-point especially if I bought "good seats". My criteria of a "good seat" is as close to the stage as possible. I'm sure that many others value the same. However, if the band or orchestra is so close to you, there is NO way in Hell that the imaging can be pin-point! It HAS to be diffuse as the sound just left the instruments & all the instruments across the stage just CANNOT combine that quickly to form a pin-point image. In fact, the further away I have sat (didn't get to Ticketmaster early enough to get that "good seat"!) the more pin-point the imaging has been. In fact, off lately, I have been appreciating the mid-hall presentation of music (whereas earlier I was almost always a front-row-center kind of guy).
So, maybe the Brits/Europeans are not that wrong in considering PRaT. They might be considering PRaT to give a wholeness to the music, which is very important for our resp. listening enjoyment.
Of course, IMHO. FWIW. YMMV.
LOL! I'm still doing research!! ;-) I'm well beyond analysis paralysis, I've officially got Jean Quary's disease... flip-floppatosis!
I'm actually going through a major speaker design theory shift right now. I have time/phase coherent speakers, so I'm now thinking about something along the lines of Ohm, Dueval, Gallo, ESS and a couple other 360 degree designs. In any event, I haven't heard anything yet that is urging me to unload my Hales.
No, there is no such thing as a "best speaker design", but not all speakers are created equally. I think speaker design/theory/approach/methodology/materials etc. is extremely important, otherwise designers wouldn't spend the extraordinary number of hours and cost to research and develop different approaches. The sound of these design theories will vary greatly in different situations and with associated upstream equipment and even with varying types of music.
If one is going to make a sizeable investment in a speaker, then it behooves the individual to do their homework. Buyers remorse is not an experience I'm interested in becoming intimate with.
Bombaywalla ... I heard the DM603s and the imaging was far below that of the Spicas, though they had much better dynamics. When I heard reviewers say that ls3/5s image well I wonder if the same reviewers ever heard tc-50s or angelus, because the ls3/5s are not in the same league.
Bomarc ... agree the proof is in the listening. That said I'm just musing as to why the spicas do the spatial thing so much better than all other comparably priced speakers. Since all spica speakers have this attribute it's not coincidence ... some aspect of Jon Bau's design directly created it, and I suspect it is attention to the time domain response.
Dawgbyte: Thanks for the info on that thread. I'll check it out when i get done posting here.
The Ohm F Walsh designs were phase and time coherent, but they can achieve this coherency only at one specific listening height. This height will vary with the distance that one is located from the drivers. The non-linear pitch of the cone for the Ohm A and the use of another radiating source in the Ohm G negate their potential to achieve time & phase coherency. Other than that, the current offerings by Ohm are neither "true Walsh's" or phase & time coherent. While i know that Dawgbyte is not alone in this, people should not lump all Ohm's that refer to using "Walsh technology" or "Walsh driver's" as being one & the same. As far as that goes, the newer Ohm's are NOT EVEN CLOSE to offering 360% of radiation at any given frequency. If you listen to them and like them, that's fine. Just don't buy the marketing hype about "Walsh technology", etc... Sean