Time coherence - how important and what speakers?

Karls- you got it right.

If you wanted to know the actual % modulation distortion, you'd have to know the stroke and frequency of the mid's vibrations that are affecting the tweeter's sound. Which are random, as far as the tweeter is concerned. Which means the modulations are unpredictable on music- so all we can say is that they should probably make the sound hazier or dirtier.

Jeff's crossover is probably the only one that could make a co-ax design work well. Even then, the tweeter dome would require a modest horn around it- a waveguide to keep the tweeter's sound from bouncing off the mid's cone. Of course, the mid's sound will bounce off that waveguide's exterior...

The "horn-loading" coloration is a common term- what we're hearing are the quasi-transverse reflections from the sidewalls of the horns, and the reflection from the mouth of the horn back to the throat.

At the mouth of the horn, the sound pressure goes from travelling in a high acoustic impedance to a low acoustic impedance. Thus, from the un-equal impedances, a reflection/standing wave takes place inside the horn. Then there is the matter of a horn's possible throat-compression ratio that boosts efficiency and distortion (love them PA horns, don't you!). You can't compress/rarify the air more than 1% or you get harmonic distortion from the air itself.

Roy

Well, Roy you share a quality with Jeff that I truly admire. You speak your mind. You also seem to share the same fault. You condemn those who take a different path. I do think that you seem to be a little overly critical of the "corporate entities". Jim Thiel and Richard Vandersteen both started their corporate entities out of their garages. Those who belittle success doesn't hold much promise for themselves. The designer who lacks 6th grade math skills (and we all know who you are referring to) seems to have fooled his university professors into giving him an engineering degree. This same designer seems to be aiming at the same target you are with his co-axial drivers (the mirror image of a microphone and it's pin point radiation pattern). You find fault with his approach. That's fine, your entitled to your opinion. It's also interesting that his success has allowed him to experiment with designing new drivers, a luxury many competitors don't enjoy. Attacking his education or intelligence doesn't seem like such a good marketing concept. I either don't remember learning this elementary math or never learned it in the first place. I'm sure I'm not alone. You may have just insulted a large percentage of potential customers. Don't worry I'm not that thin skinned. I can't help but feel that one can be opinonated and back up one's position with mathmatical evidence and still be diplomatic. See, I really do want you guys to succeed. I applaud both of you for sharing the evidence that brought about your design philosophies. I look forward to more from both of you and hope you lead others to be so frank.

I want to make an empirical observation about my Ohm Walsh 300's. They sound good to me no matter where I am in my apartment. I give their coherent sound credit for this. The only complaint that I have is that they won't play loud enough for some heavy tunes that I occasionally listen to. Roy's observations sure seem correct. I can't do this now but someday I would like to add a dedicated subwoofer to handle the lows. I think this will solve all problems.

I actually like some of my competitors! (even if I have differing ideas regarding design execution) I've met Roy many years ago at the Florida show and he struck me as a very nice fellow. Same for Pat McGinty.
David & Sheryl Lee Wilson came by and sat through my presentation during the last show, and David stayed and shook my hand afterward. Peter McGrath dropped by shortly thereafter. I've called upon guys like Ken Kantor and Michael Kelly for their advice, and they've always been gracious and accomodating. While the product is very important, a speaker company must be more than the product. The most sucessful companies know that you must take care of the customer after the sale. Ya gotta admire the people at Vandersteen, Thiel & B&W who take care of their consumers and do right by them. It's no small task, and they have set a standard of service that we try to emulate every day.

I'm surprised nobody has mentioned Von Schweikert speakers in this discussion of time and phase coherent speakers. Anybody have any opinion on Von Schweikert speakers as they fit into this discussion? BTW, I asked Albert Von Schweikert how he achieved time and phase coherence with a 4th order crossover. He gave me a very lengthy response to my e-mail, which was very interesting, but I am not sure he answered my question. Can anybody help ?