A Question About Time Alignment

It seems to me, however, that live music isn’t time aligned. Suppose I’m playing the piano and you’re sitting across the room. When I stretch out my left hand to hit the low notes, those notes travel along the same long, slow wavelengths as the notes from Wilson’s woofers. Similarly, the treble notes I play with my right hand move quickly through the short wavelengths. The notes from the piano are naturally out of alignment.

 

Something must be wrong with my line of reasoning. Would someone please point out where I’ve gone wrong? Nicely?

The time it takes for the low notes to arrive at your ears is slower than the highs no t because they are inherently long but because the voice coil of the woofer is mounted behind the baffle whereas for the tweeter it is mounted almost about the same level as the baffle hence the tweeter is closer to yours ears than the woofer. 

With a real piano, various sounds come out of it from various distances. These relative distances must be preserved by the speaker hence the requirements for time cohesion. 

The problem only occurs with reproduction. It does not apply to live music. All frequencies travel at exactly the same speed depending on the barometric pressure (air density). The problem is cause by crossover design, when certain frequencies are shifted in phase. It can also be caused when drivers are placed in disparate locations such as frequently occurs with subwoofers. Definition and imaging improve when a system is "time aligned." This can be easily demonstrated with digital crossovers that have control over delays. The problem that occurs when adjusting time alignment with driver location is that perfect alignment can only occur along the centerline between the speakers, but then that is where you only get a proper image anyway. The best solution to the problem is a single driver and no crossover except maybe to a subwoofer with digital time alignment. 

The time it takes for the low notes to arrive at your ears is slower than the highs no t because they are inherently long but because the voice coil of the woofer is mounted behind the baffle whereas for the tweeter it is mounted almost about the same level as the baffle hence the tweeter is closer to yours ears than the woofer.

Maybe instead of “slower”, do you mean “delayed”?

The former is speed/velocity, and later seems more like time/distance.

in colloquial speech fast or slow refers to time. For example fast food refers to food that is prepared quickly. There is no mention of distance in that.

There is so many partial truths and misinformation in this thread about time and phase aligned speakers. I strongly suggest digging through past threads here on AudioGon on the subject.