A Question About Time Alignment

I have a time alignment system in my car that allows me to make minute adjustments between woofer, midrange and tweeter.  

this function does make a difference in sound quality but it is more of an advantage aligning left to right speakers in a car interior setting.  

time aligning the individual drivers of one speaker does have some benefit but you may not find big gains in sound quality. 

the best thing it can do for you is to align the speakers at their crossover frequency 

which avoids out of phase cancellations of frequencies and adds coherence and more of a point source focus of the sound image.  this will lead to a flatter frequency response and better imaging. .  

you will need test tones and pink noise with measurement tools to get the most out of it.  no way you can adjust by ear with music. 

I was taught the same about time alignment, slanted front speakers ..., the amount of time alignment difference is relative to seated listening distance of course, and the differences are very very very small, yet it could be bunk.

Related is the issue of keeping your speaker wires the same length. The lengths we use are very small relative to signal speed, but, I still follow the rule. Makes a big difference using expensive cable.

Your point about no time alignment for live music is valid, the drums are way in the back, violins up front, the opposite of what slanted front speakers do.

below they mention a band in a stadium, much greater distances.

I just found this, scroll down some

https://phys.libretexts.org/Bookshelves/College_Physics/Book%3A_College_Physics_(OpenStax)/17%3A_Physics_of_Hearing/17.02%3A_Speed_of_Sound_Frequency_and_Wavelength#:~:text=a%20smaller%20wavelength.-,Summary,s)%E2%88%9AT273K.

High and low frequency signals travel exactly the same speed.  Proponents of fully time aligned systems like Vandersteen and Thiel, are concerned with say, 1 note of a horn looking like 1 note from a horn when it reaches your ears.  Many benefits are supposed to come from this, like increased imaging, clarity, etc.

Time alignment however is the minority approach when it comes to speaker design.  Hard to implement in passive crossovers and may over-stress tweeters. 

From a personal perspective, I have never heard a time aligned speaker which sounded so good I'd forego all others forever for it.

We should also be careful about not confusing time-aligned with phase-aligned.  Phase alignment is similar, but only concerned with the correct and smooth sums from multiple drivers through the individual crossover regions. 

@carlsbad (edit: and @erik_squires) has/have it exactly correct: all frequencies travel at the same speed---the well-known "speed of sound".

As to time alignment of the drivers, a major objective in a multi-driver loudspeaker is to get the different drivers to be in phase with one another, especially at the crossover "point" (read on). At that crossover point (not a single frequency, but the frequency range withing which driver outputs overlap), if two involved drivers are in phase, their combined outputs will "fill in" the declining slopes of both drivers, thus producing a flat freqency response (for instance, the falling output of the low end of the tweeters output and the falling output of the high end of the midrange drivers output. Those declining outputs are the consequence of the two drivers raw responses combined with the crossover filter slopes). If the two drivers are not 100% in phase at the crossover frequency, that won’t occur "completely", and there will be a "dip" in response. It’s complicated, but drivers are referred to as having certain "degrees of phase rotation", a subject far too technical to explain in this post. The information is available in the literature.

But there is another consideration. "Time aligned" drivers are aligned at a given listening position, that position in relation to the drivers. In his excellent YouTube videos, Danny Richie of GR Research demonstrates how moving a measuring microphone (which is a substitute for ears) effects the phase relationship between drivers. Two drivers in phase at a listening position equidistant between two drivers can become somewhat or even significantly out-of-phase when the mic is moved above or below that equidistant position.

"Time aligned" has become a marketing buzz word, but it is an over-simplification of the complex relationship between drivers in all multi-driver loudspeakers with crossovers. Just buy a Sound Labs or Sanders full-range ESL, a planar-magnetic dipole (Eminent Technology or Magnepan), or a loudspeaker designed by Danny Richie ;-) . The latter are available only as DIY kits, but you can do it!

PS - Looking at the step response (Figure 5) this is not a time-aligned speaker.  If it were there would be a single rising impulse followed by a long decay.  The two peaks are indicators that these speakers are phase aligned.