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A Question About Time Alignment

I was reading a review of the Wilson Alex V on Stereophile recently. (Published just in time. I’m thinking about picking up a pair. Maybe a couple for the bedroom, too.) And it raised a long-standing question of mine, one that I hope the wiser minds on this site can answer. 
 

Wilson’s big selling point is aligning the different frequencies so they all reach your ear simultaneously. As I understand it, that’s why they have minute adjustments among the various drivers. The woofers put out bass notes that move slowly thanks to their long sound waves while the tweeters are playing faster moving, high frequency notes with short waves. Wilson lets you make adjustments so that they all arrive at the ear at once. 
 

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. If Wilson’s goal is to achieve a lifelike sound, aligning the frequencies doesn’t seem like the way to do it. 
 

Wilson has been selling lots of zillion dollar speakers for lots of years and people continue to gobble ‘em up. Something must be wrong with my line of reasoning. Would someone please point out where I’ve gone wrong? Nicely?

paul6001
carlsbad's avatar
carlsbad
1,551 posts
 

I haven't studied wilson speakers of their claims.  However, as a physicist, I'm pretty sure the speed of sound is independent of frequency.  Maybe lower frequencies leave the transducer slightly delayed.  My initial reaction is skepticism.

Jerry

overthemoon
417 posts
 

I think it’s the difference between playing vs reproducing a recoding. 
 

Though I am purely hypothesizing. 
 

I imagine a drummer using symbols and kick drum where frequencies travel at different speeds and are captured by a microphone. Then the recording is played back and the timing is impacted by the crossovers. 
 

if you like how Wilssound does it matter why?  I view I am paying for the results not the knowledge. 

avanti1960
1,458 posts
 

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. 

elliottbnewcombjr
5,304 posts
 

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.

 

 

erik_squires
16,009 posts
 

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. 

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