Time coherence - how important and what speakers?

ALso...Spica tc-50s were designed and marketed as a truly time and phase correct speaker...I know there is alot of jargon these days..."phase correct","phase coherent",etc...but the spicas...like Vandersteen, meadowlark,Thiel,etc...were the real deal...with that said...they were not a perfect creation...the highs were rolled off, they had very little bass, and were not very efficient...however...their 3-d imaging&spacious qualities as Roy mentioned were their claim to fame...and why they still fetch 3-$500 used almost 20yrs later...not much more than they retailed for back in the day...a great speaker during its heyday...and a fine value...but a bit outclassed today...especially in the detail department...at even at the $500 level...

Roy...do you have a dealer in the midwest?...I would love to audition the Europas...cheers...or do you have any b-stock/demos available?

Cdc- Thiels use a complex crossover circuit to force first-order acoustic rolloff responses from the drivers, because of their driver choices and cabinetry. Dunlavy and to some extent, Vandersteen employ similar approaches.

Your question about a single driver- if there was one with a perfect cone, free of breakup, the end result would be little bass response and very narrow dispersion in the highs. To widen dispersion in the highs and extend high-frequency response, a whizzer cone is attached, driven through a mechanical crossover (the adhesives used) between it, the voice coil, and the main cone. Those type of crossovers at best are 2nd-order, which means there's 1/2 wave-period of time delay at the crossover point. There are cone breakups usually still present. There are standing waves in the whizzer, reflected from its un-terminated outer rim. Those all are responsible for less than pinpoint imaging. At least their designers get to leave off any electrical crossover, which is a good thing, considering how much information is lost in most of circuits. Whizzer-cone drivers are not time coherent, but just less imperfect that most speakers that do use a crossover.

Phasecorrect- just remember that "phase correct" and "phase coherent" do not mean "time coherent". The converse does. See my first 02/12/03 post above.

Best,
Roy

I dont believe Vandy or THiel use "complex" x-over circuitry...these are afterall pioneering first order time and phase correct speaker designers...both Richard and Jim...and as RIchard V has openly stated...there are only a handful of truly time and phase correct speakers on the market...SPica would be the one that fall into a more complex x-over category...

I'm not sure about the Vandersteens, but, I do think some of Jim Thiel's crossovers are quite complex. I suspect his goal of amplitude coherence has something to do with this. I suspect that the complexity of his cross-overs is what accounts for the low yet narrow impedance of his speakers. Have you ever seen the one Thiel used in the CS-5. Some have criticized him for this, complaining that his cross-overs suck the energy out of the performance and add a veil to the sound. Yet others critcize his products for being too "analytical" and "clinical" sounding. Go figure? Of course due the the mechanical cross-over nature of some of his new co-axial drivers, the electrical crossovers have simplified. On the other side of the spectrum I think that the Meadowlark offerings use a different set of priorities and accomplish their results with a simpler crossover. Mind you I enjoy all of the above manufacturers products. In as much as one can readibly identify from whose pen what product came from, I still think they have more in common than not. To me, there is something that just sounds more "right" about them.