A Question About Time Alignment

My Sonner Legato Unum are time aligned and sound fantastic in my system. 

As are the entire Sonner line.  Simply a wonderful speaker no matter what amplifier I use. Much of this is due the the driver time alignment. 

The Legato Series was engineered in a way that they can be driven by a small or large vacuum tube or solid state amplifier and easy placement or set up in a room. Sophisticated cabinet design utilizing one piece molded curve cabinet, state of the speaker drivers, and high quality crossover components work in harmony with our Symmetrical Panoramic design crossover network to deliver a natural sound, effortless micro and macro dynamics, huge soundstage with a sense of air around the musician and instrument while maintaining music emotion.

This series was created to deliver musical expression, huge soundstage and vivid imaging on a small foot print with a more attainable price point.

TECHNOLOGY

At Sonner Audio, our focus is on providing you sound quality that is authentic and emotionally rich. Our Creative Development Team finely tunes each speaker beyond computer modeling and simulation, with extensive human listening tests to bring a completely unique, realistic and dynamic experience to fellow music enthusiasts like you.

 Sonner Audio Legato Unum Loudspeaker | REVIEW - Part-Time Audiophile (parttimeaudiophile.com)

Google:

Physical time alignment of drivers is accomplished by building them into the cabinets so that the magnets/voice coils are vertically aligned so they are radiating the same info in temporal alignment, reaching the listeners ear at the same time.

What is audio time alignment?

In other words, the high frequencies and low frequencies much reach the listener's ear at the same time. A system which meets this criterion is said to be “time aligned.” One way to accomplish this is to place the tweeter further away from the listener than the woofer, and this is done in many speaker systems.

ASR answer to the question:

Suppose you (the woofer) hit the bass keys of the piano and someone else (the tweeter) hits the treble keys, but not at the same time. The music is no longer time aligned. But if you both hit the keys at the same time, is is aligned even though one frequency gets to the ear first. It's part of the experience of listening to the piano.

So yes, moving the drivers does change the time/phase alignment, BUT!!

It does not alone ensure a perfect impulse response. :D

However, if you align driver's acoustic centers, it means that the crossover works better off axis.

Let me clarify a little.

Each driver has a different distance to it’s acoustic center. Tweeters are shallow, woofers are deep, and we must take this into account in designing the crossover.

Here’s the problem. From the front the tweeter is say 2" closer to your ear than the woofer but at 90 degrees to the side they are the same distance. This means that the phase relationships you take into account in the crossover only hold perfectly true in front of the speaker.

If on the other hand we step the drivers back so that the acoustic centers (usually near the magnets) are exactly aligned, the phase relationship directly in front and at the sides is the same.

Great! this simplifies crossover design. However, if you look at an impulse response in either case, they will still not be perfect. That is more involved. :-)

Another approach here is also to use higher order filters, which D'Appolito recommends for MTM designs.  Steeper filters (also like Joseph Audio's older infinite slope speakers) minimize the phase matching problem off axis in all directions.