A Question About Time Alignment

I have read through this thread over the past few days and have purposely stayed out.  There are some reasonable explanations in this thread and others that don't show a real understanding of time & phase..... I will try to provide an accurate and very simple explanation.   

Over all time alignment is addressed.  All frequencies travel at the same speed,  Just because one frequencies wave length is longer, does not mean that the frontal wave of one frequency will reach you at a different time as another.  

On speaker design what we align is the portion of each driver where the sound is emitted, which is normally, aligning the front of each voice coil.  This allows all drivers sound to reach the ear at the same time. .... drivers can be staggered or sloped.   

Phasing.... fairly simple actually.... If it were possible to have a PERFECTLY phased speaker, which does not exist, 2 way, 3 way 4 way does not matter.  In each of these speakers, perfect phasing means all speakers cone movement would operate in unison.  This really cannot happen, so perfect phase cannot happen.  What we normally do is to get phase alignment at the crossover frequency.  When each driver is in phase at the crossover frequency, you normally get a quite good sound stage.  Each crossover type will cause some sort of phase shift, normally 60 to 180 degrees out of phase.  With alot of work, I have seen some drivers as close as 15 degrees of absolute phase with another, but normally achieving near phase alignment at the crossover point works very well. If you think about it in frequency, its fairly easy to understand why you cannot achieve absolute phase alignment. a tweeter may produce 3000 hz and up, well its obvious that the tweeter is moving at 3000 cycles per second, so a woofer moving at 60 cycles, obviously cannot produce sound waves in perfect unison.  Each driver does its job and we do the best that we can to produce time and phase alignment.  The better that alignment the better soundstage and imaging are produced.   If you think about it in the deepest sense,  Phase really is time, if drivers are out of phase with each other, frequencies are leaving the drivers at different times, thus effecting time alignment.  I hope this all makes sense and helps in some way.  Tim

Hello Everyone,  Since Kenjit mentioned me, I thought that I'd clarify his comments:

I often get a pm from others asking for help and EVERYTIME until Kenji I have helped others.  Kenji contacted me asking for help with his speaker design.  While asking for my help,  He quoted designers, telling me "how it is and how I must design his speaker"...He was convinced that only Linkwitz Riley design could achieve a proper summed response.  I explained that in his case,  I would not be using Linkwitz Riley base design, but in the end would end up with Linkwitz Riley Alignment.  He argued until, I said forget it, do your own.... I had designed a near perfect anachoic flat response and told him that we needed a starting point and a flat response is it.... He accused me of not listening to him and didn't understand that a flat response is the starting point and we could tune from there. He had not at that point did he reveal what type of customization that he wanted .. I asked and found that he wanted a very specific frequency curve.. I did some basic work and again sent him info of how to achieve the frequency curve that he was trying to produce. He then proceeded to tell me that he has been burnt before from someone else and really had no trust for anything that I would do, but wanted me to dive in deep to prove to him that I could achieve a very specific frequency curve that he wanted to achieve. .... What he wanted was not crazy difficult.  I actually did the basic design, but still needed FRD and IMP to give him completely accurate info. He told me again that because of his history and mistrust for me that he may not ever even build what I sent him because crossovers can be expensive. I told him that he had no trust for me,  no respect for my time and no trust.  I would not move forward..... I told him to provide me frd and imp files and I would consider knocking this out for him... He did not send them and I was not going to waste any more time on Kenji.  

Now you see his response to me in this thread.   

Have fun with Kenjit.....

Phase really is time, if drivers are out of phase with each other, frequencies are leaving the drivers at different times, thus effecting time alignment.  I hope this all makes sense and helps in some way.  Tim

No you are just confusing the issue even more. Phase and time are two different things. time cohesion implies phase cohesion but not vice versa. So not equivalent at all. Time coherence between two drivers is about aligning the start of the waves coming out of each driver. You can have phase aligned yet time non aligned. 

Phase and time in speakers is very related, that is why I said in a sense... If you are out of phase, normal time alignment procedures will not time align. 

On speaker design what we align is the portion of each driver where the sound is emitted, which is normally, aligning the front of each voice coil.  This allows all drivers sound to reach the ear at the same time. .... drivers can be staggered or sloped.   

This is also nonsense. 90%  of speakers are not sloped or staggered and nobody is complaining. Time alignement has never been proven to be beneficial let alone audible it is only for marketing. 

It isn't nonsense at all.... I've never said that you cannot have a musically satisfying speaker without absolute time alignment... I was only commenting on how to achieve the objective being discussed, by the way, it is beneficial and audible.  

I am very disappointed in you Tim. Was waiting for your custom tuned circuits and they never materialized.

Actually Kenji,  the disappointment is mine.  You have disrespected me at every turn while asking for my help.... It doesn't sit well to have a Master Speaker tuner and Master Audiophile that is so uncapable of doing his own work to come to me with no humbleness and then post this publicly.... 

~Master Kenjit, speaker tuner and master audiophile.

@kenjit       Nope

@paul6001     Sorry that I derailed your thread with Kenjit,  but overall and I can tell you that a handful of people that gave you answers had a very good understanding and gave accurate answers. It looks to me that regardless of the many answers, most concur.  The speed of sound makes all frequencies travel at the same speed regardless of wavelength.  Phasing does matter to some degree, but is not the be all end all.  

I can tell you that there are differences.  I have taken a nice 2way out of a standard type of cabinet and switched it to a sloped front cabinet. To be fair, also changed the crossover a bit to compensate for listening angle at the seating position, but in the end.  I was able to add depth to the soundstage as well as a more pinpoint placement of instruments...  Overall,  in some speakers, it may not be dramatic, but in others, depending on design, it very well could be.   Good luck,  I hope this helps in some way,  Tim

Back in my old days at Marcof,  Ed Built a few Turntables that were very good, however,  He modified several arms, but I have never seen him attempt to build an arm.