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Questions Re: Time & Phase Alignment

Some basic questions here. Hope nobody minds. Some of this stuff I don't quite understand. Have recently become very interested in T&PA after hearing both the Green Mountain C3 and Thiel 3.7 at RMAF, both of which tout this design quality and both of which were among the best speakers I've ever heard, anywhere.

Questions:

1) Basic definitions. Time-alignment means that sounds that start at two different drivers at the same instant will reach your ears at the same instant.

Phase-alignment means that there are no phase errors between drivers: the same frequency waveform, for example, produced by two drivers (in their overlap region) will be entirely in phase with each other (and thus completely reinforcing).

Are these definitions correct, correct but lacking, incorrect, or what? I find there is a lot of either misinformation or misunderstanding in the industry about these things.

2) How does a sloping baffle produce time-alignment? I really don't understand this - I would think that having the voicecoils of all drivers in the same plane would, in fact, produce time-alignment. Is the slope to compensate somehow for the crossover?

3) On that note, I don't understand why it is that 1st-order crossovers are phase-aligned. Perhaps this is stricly due to the implmentatation - a single cap produces no phase delay? But I don't think that's the case... so why is it that 1st-order xovers are said to be p-aligned and higher-order xovers are not...? Or is that, perhaps, myth?

3) Thoughts on the superiority of coincident midrange driver/tweeter vs. completely separate drivers? I certainly see the benefits of the former but it must introduce some problems as well - there must be distortions caused by the entire tweeter assy moving with the mid driver.

Thanks much in advance to someone who can shed some more light on these topics.
paulfolbrecht
paulfolbrecht OP
603 posts
 
Roy gave me this very sensible response to the coincident driver issue: "Regarding co-incident drivers: Any 1" dome tweeter, below 5kHz, wants to radiate in an omni-directional pattern. This means that much of the sound you would hear from a co-axial mid/tweeter driver in the lower treble comes to you secondarily by way of bouncing off of that mid's cone. Even a short horn around the tweeter cannot prevent this (because it is short). A high-order crossover can help reduce that secondary 'splash' off the mid's cone, by chopping off the low-end of the tweeter even more rapidly."

Hopefully he wouldn't mind me posting it (can't see why not).
macrojack
1,303 posts
 
With Vandersteen, Thiel and Green Mountain you are exploring some of the speaker manufacturers who have been most successful in coping with the inherent difficulties and problems of crossover design. There is a growing movement toward single driver systems that entirely eschew the whole crossover controversy by excluding them entirely from speaker design. Your posts suggest that you may well be interested in exploring such an option. Naturally there are tradeoffs involved but the Zu products have minimized the sacrifice necessary for such an exchange. Since buying Zu Druids about a year ago, I have become active with the company and have a loose relationship with them that has business potential. I am not a dealer, per se, but I am in a position tp profit if a demonstration in my home ever leads to a factory direct sale. Otherwise I am no different than any other audiophile with preferences. This info is offered to indicate the potential for bias in my comments due to factory affiliation.
I would recommend that you call Sean Casey at Zu and ask these questions of him. He has always been very helpful.
paulfolbrecht OP
603 posts
 
I have Zu Druids in my 2nd system. They are very nice speakers. However, they are not in the SOTA league of such $10K+ speakers as the new Thiels and higher-end Green Mountain C3s.

I already have great speakers in my Hyperion and Zus. I'm kinda looking for, now, what might be the be-all-end-all, truly SOTA speaker. At this point, to me, that means full freq-response, multidriver, dynamic, and time and phase-aligned.

So, yes, I'm familiar with Thiel & GM, but have never heard Vandersteens.

I sort of have two thread going now with very similar topics... sorry about that.
gregm
3,399 posts
 
(Speakers which are) full freq-response, multidriver, dynamic, and time and phase-aligned
That's a tall order, my friend.
I strongly recommend you forget it: multidriver, & phase + time aligned don't go together. You will laways have phase matters with many drivers.

Well performing full-range passive spkrs are extremely expensive. Often they are not practical; heavy, difficult to drive, to place, subzero waf, etc.

If I may be so bold, ENjoy what you have. Cheers!
mauiaudioman
171 posts
 
Paul, I own the new GMA Calypso's and they are very, very impressive speakers. I agree with others that say search the archives here for comments by "RoyJ" (Johnson of GMA) and also by "Karls" (Karl S. of Audiomachina), both very well versed on time/phase coherence. To my ears (30 year musician) a time/phase coherent speaker like a GMA brings you closer to the music than a non time/phase design. Once you own a pair of time/phase coherent speakers, you will find it pretty much impossible to go back. My opinion only.....for what it's worth to you. E-mail me if you have any questions I can answer for you about the Calypso's.
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