# Subwoofer Time Alignment. Thoughts?



## snow3d (Feb 8, 2012)

Just got done doing some TA on my fronts, and I think I finally got it right. Quite the improvement. However, I am wondering if it's necessary to do TA on my sub though due to it's location. 

I have a van with a bulkhead installed just behind the front seats, and the subwoofer is up front in the cabin. Due to the lack of space I had to install the sub between the seats. So the sub is actually closer to my right ear than the right side speakers. 

I played around with aligning the sub based on it's distance, but it didn't seem to do much. In fact it sounded a bit off. It seemed slightly tighter around the low pass @ 63hz but sloppy and distant below about 50hz.
Overall the sub blends much better with no TA on it at all.

Is the close proximity of the sub to my ears offsetting the natural delay of the sub bass frequencies rendering the need for TA useless in this case?

Thoughts?


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## 07azhhr (Dec 28, 2011)

Did you play with it's phase at all when you TA'd it?


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## Dillyyo (Feb 15, 2008)

snow3d said:


> Just got done doing some TA on my fronts, and I think I finally got it right. Quite the improvement. However, I am wondering if it's necessary to do TA on my sub though due to it's location.
> 
> I have a van with a bulkhead installed just behind the front seats, and the subwoofer is up front in the cabin. Due to the lack of space I had to install the sub between the seats. So the sub is actually closer to my right ear than the right side speakers.
> 
> ...



You need to set the TA via whatever method you are choosing and then you need to play with the phase to dial it in. If you don't have the ability to alter phase by anything other than 180 degrees, then you will need to play with the distances and trying to flip polarity and see what is giving you the best response.


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## [email protected] (Nov 7, 2010)

What orientation is the sub in?


Sent from my iPhone using Tapatalk


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## snow3d (Feb 8, 2012)

Guess I should state that I have no issues with the way the system sounds. It's actually almost perfect. I'm just wondering if I can split a few more hairs and make it more perfect. 

The question I ultimately have is one that I believe requires some math and theory to explain. Any amount of TA I put on the sub makes things sound a bit off. 

So again, here is my original question: 

"Is the close proximity of the sub to my ears offsetting the natural delay of the sub bass frequencies rendering the need for TA useless in this case?"


@ Joey: The sub is firing rearward toward the bulkhead. Tried it forward, down, up. Rear firing sounds the best.


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## mojozoom (Feb 11, 2012)

Typically the goal with subwoofer alignment is to get perfect phase alignment at the crossover point when measured at the listening position. With the almost random collection of distances and phase shifts due to the various filters in play it's almost impossible for the sub to be perfectly aligned to the mids right off the start in any given installation.

But, in order to split those hairs you'll probably need to be able to measure the system's response.


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## minbari (Mar 3, 2011)

if you did your T/A without the sub, you did it wrong.

T/A should always have a reference point. that reference point should be the speaker that is farthest away. this is almost always the subwoofer.

in short, you dont need to T/A the sub, because it is the zero reference point from which you T/A all the other speakers.

T/A your sub to each midbass first, then the misbass to the mids(if you have them), then tweeters.

tweeters are least important.


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## Jroo (May 24, 2006)

Sorry to jump in, but I finally have a deck that does TA and have heard different things. I have in fact heard that you base your TA off the sub because it farthest speaker away. Basically I was told to TA all my speakers around the sub. I was told that your Tweeters are the most important speaker to TA as they are the easiest to localize? What I am being told is that you make sure tweeters and mids are TA and your midbass and subs you worry about least becasue as you move down the spectrum they are the least easy to localize?

I think this was also told to me becasue of the amount of channels I have to process. Basically TA the Tweet and MId, then get the eq, phass, and xover points right on the mid bass and subs?


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## minbari (Mar 3, 2011)

Jroo said:


> Sorry to jump in, but I finally have a deck that does TA and have heard different things. I have in fact heard that you base your TA off the sub because it farthest speaker away. Basically I was told to TA all my speakers around the sub. I was told that your Tweeters are the most important speaker to TA as they are the easiest to localize? What I am being told is that you make sure tweeters and mids are TA and your midbass and subs you worry about least becasue as you move down the spectrum they are the least easy to localize?
> 
> I think this was also told to me becasue of the amount of channels I have to process. Basically TA the Tweet and MId, then get the eq, phass, and xover points right on the mid bass and subs?


its not a matter of localization. that is not why you T/A a system. it is to get the phase aligned on all the drivers. a tweeter is least important because you have the least amount of phase change through the pass band. some people dont even bother with T/A on the tweeter.


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## MarkZ (Dec 5, 2005)

snow3d said:


> Is the close proximity of the sub to my ears offsetting the natural delay of the sub bass frequencies rendering the need for TA useless in this case?


What natural delay are you referring to?


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## MarkZ (Dec 5, 2005)

Jroo said:


> Sorry to jump in, but I finally have a deck that does TA and have heard different things. I have in fact heard that you base your TA off the sub because it farthest speaker away. Basically I was told to TA all my speakers around the sub. I was told that your Tweeters are the most important speaker to TA as they are the easiest to localize? What I am being told is that you make sure tweeters and mids are TA and your midbass and subs you worry about least becasue as you move down the spectrum they are the least easy to localize?
> 
> I think this was also told to me becasue of the amount of channels I have to process. Basically TA the Tweet and MId, then get the eq, phass, and xover points right on the mid bass and subs?


Whoever is doing all this "telling" to you doesn't know their ass from a hole in the ground.


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## snow3d (Feb 8, 2012)

I appreciate the input here, but please read the original post. The subwoofer is not the farthest speaker away from my ears. After applying some rudimentary maths, it seems that TA is not necessary on the sub due to its location between the front speakers. At least that is what my ears tell me.

The right midbass speaker is the reference point as its the farthest away. So due to it's location between the fronts, putting any TA on the sub creates a weird delay and makes it sound like it's in the back of my van. 

Are my ears lying to me?


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## minbari (Mar 3, 2011)

I must have missed that part. If it sounds right, then I am sure it is


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## snow3d (Feb 8, 2012)

MarkZ said:


> What natural delay are you referring to?


The fact that sub bass frequencies travel slower than higher frequencies. Which is why you normally use TA to align everything else to the sub.


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## minbari (Mar 3, 2011)

snow3d said:


> The fact that sub bass frequencies travel slower than higher frequencies. Which is why you normally use TA to align everything else to the sub.


lol, what scientific bassis do you have to prove that low freq sound moves slower than high freq sound?

again, that is not what T/A does at all. it aligns the phase difference from speakers being in different locations. the distances of those locations make the sound arrive at different times. T/A (as the name implies) aligns those differences.


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## MarkZ (Dec 5, 2005)

snow3d said:


> The fact that sub bass frequencies travel slower than higher frequencies. Which is why you normally use TA to align everything else to the sub.


They don't travel slower than higher frequencies. As minbari pointed out, most people set the sub as the reference point (delay = 0) because it's usually the furthest speaker. In your case, find the furthest speaker from you and set that to delay = 0.

Time alignment is just one piece of the puzzle. If time alignment is screwing things up, then most likely it's because a non-optimal delay setting is actually correcting for some phase issue. Which is fine, really. But in an ideal world, you'd set time alignment correctly and then adjust phase directly.


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## Dillyyo (Feb 15, 2008)

snow3d said:


> The fact that sub bass frequencies travel slower than higher frequencies. Which is why you normally use TA to align everything else to the sub.


We are on planet Earth and that theory you are presenting holds no water here or anywhere we are aware of. With that said, do yourself a favor and time all speakers, even your sub, using the farthest speaker as your reference. Once you get this all done then there will likely be a need for some tweaking of distances and phase. 

If you used a manual distance measurement process, then you could very well need to play with the distances of each speaker until you get a good center image and good staging. This will mean you also need to play with the distance inputs for the sub and phase shifting, if you have the ability to do that. If you used software and did impulse response measurements, you could very well be locked in right after completion.


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## snow3d (Feb 8, 2012)

minbari said:


> lol, what scientific bassis do you have to prove that low freq sound moves slower than high freq sound?
> 
> again, that is not what T/A does at all. it aligns the phase difference from speakers being in different locations. the distances of those locations make the sound arrive at different times. T/A (as the name implies) aligns those differences.


Umm...ok maybe that statement is a bit of a misnomer, as it's not scientific fact rather the way our ears perceive those sounds. Low frequencies occur less frequent than higher ones make our ears slightly less sensitive to those frequencies. The human ear is most sensitive from about 300-3k.

I'm really just curious as I have no apparent phasing issues, everything sounds really good. Just wondering what someone with a keener ear would hear in my van.


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## minbari (Mar 3, 2011)

snow3d said:


> Umm...ok maybe that statement is a bit of a misnomer, as it's not scientific fact rather the way our ears perceive those sounds. Low frequencies occur less frequent than higher ones make our ears slightly less sensitive to those frequencies. The human ear is most sensitive from about 300-3k.
> 
> I'm really just curious as I have no apparent phasing issues, everything sounds really good. Just wondering what someone with a keener ear would hear in my van.


your ability to perceive the amplitude of a specific freq has nothing to do with how fast it moves through the air. although true that we dont hear all frequencies equally, this can be adjusted with eq and/or power.

you would have to get someone that you belive has better hearing and see what they think. In the end, if you think it sounds really good, who cares if it is adjusted for someone else?


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## MarkZ (Dec 5, 2005)

snow3d said:


> Umm...ok maybe that statement is a bit of a misnomer, as it's not scientific fact rather the way our ears perceive those sounds. Low frequencies occur less frequent than higher ones make our ears slightly less sensitive to those frequencies. The human ear is most sensitive from about 300-3k.
> 
> I'm really just curious as I have no apparent phasing issues, everything sounds really good. Just wondering what someone with a keener ear would hear in my van.


What are "apparent phasing issues" and how can you tell if you have them? You're telling us that the sound of your bass is changing when you change delay. That usually has more to do with phase than with localization. So yes, you absolutely have phase issues.

Everybody has phase issues when they change delay or phase. That's kinda the point. 

If your processor doesn't have the ability to change phase in a continuous manner, you need to be playing with three things: 1) polarity; 2) delay; 3) crossover points/slopes/Qs. These are all band-aids for solving the phase issues, but can still be effective.


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## snow3d (Feb 8, 2012)

MarkZ said:


> What are "apparent phasing issues" and how can you tell if you have them? You're telling us that the sound of your bass is changing when you change delay. That usually has more to do with phase than with localization. So yes, you absolutely have phase issues.
> 
> Everybody has phase issues when they change delay or phase. That's kinda the point.
> 
> If your processor doesn't have the ability to change phase in a continuous manner, you need to be playing with three things: 1) polarity; 2) delay; 3) crossover points/slopes/Qs. These are all band-aids for solving the phase issues, but can still be effective.



I think I did a piss poor job of explaining my question, and somehow I've created a debate around a problem that doesn't exist. If I add delay to the sub, then I have phasing issues, and reversing it's phase does not fully correct this. When I leave the sub uncorrected it sounds like it should.. 
I think I led yall to believe that I have sloppy bass or something, which is not the case. Just wanted to know why it sounds better with no TA when logic says it should be delayed. 

I'm definitely happy with the way things sound, which I will attribute to a bit of luck and magic. And on that note I'm going to kill this thread because I feel like I've wasted too much of your guys' time already with my semi-incoherent ramblings.

Thanks for the info tho.


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## minbari (Mar 3, 2011)

pure luck? maybe you have a phase shift on the sub that just happens to coincide with it sounding good where it is.

either way, if it sounds good, leave it alone


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## MarkZ (Dec 5, 2005)

snow3d said:


> Just wanted to know why it sounds better with no TA when logic says it should be delayed.


Been answered. 

In short: the time mis-alignment is correcting for a phase issue.


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## snow3d (Feb 8, 2012)

minbari said:


> pure luck? maybe you have a phase shift on the sub that just happens to coincide with it sounding good where it is.
> 
> either way, if it sounds good, leave it alone


Agreed, and thank you. I will now put my OCD to work on another project.


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## snow3d (Feb 8, 2012)

MarkZ said:


> Been answered.
> 
> In short: the time mis-alignment is correcting for a phase issue.


Perfect! Exactly the answer I was looking for. That makes sense to my brain.


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## Grindcore (Dec 12, 2012)

minbari said:


> if you did your T/A without the sub, you did it wrong.
> 
> T/A should always have a reference point. that reference point should be the speaker that is farthest away. this is almost always the subwoofer.
> 
> ...


EXACTLY


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## ErinH (Feb 14, 2007)

snow3d said:


> If I add delay to the sub, then I have phasing issues, and reversing it's phase does not fully correct this. .


You misunderstand time alignment, then. 

t/a is phase shifting the sound between two or more speakers. it's as simple as that. the only thing you're doing with t/a is altering the combing pattern. this is why t/a actually has a pretty significant response on tweeters between just a few clicks of adjustment (the wavelength is shorter and the combing is more audible) and why incremental T/A on a sub or midbass is harder to tell an immediate difference in small doses (the wavelengths are so long).


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## MarkZ (Dec 5, 2005)

How incremental do you mean? 0.5ms of delay is shifting 80Hz by like 20 deg or so. That's very audible.

You crazies with your 0.01ms resolution ruin everything.


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## ErinH (Feb 14, 2007)

0.02ms. change it a few times on the tweeters and there's a very audible difference. i showed this to a new guy yesterday and he understood what I meant.

with subs, it's different. it takes a good deal of delay (ie: a whole lot more than 3 or 4 clicks @ 0.02ms) to notice any appreciable difference. I can typically move the relative* sub delay in 45 degree increments before I notice a real difference.


* relative = either the sub or the midbass wrt the sub



edit: with the tweeters, it's not so much where in the soundstage you position them (that's really almost all levels). the t/a affects phase. and by that I mean, one click in one direction may give me smearing and/or a diffuse stage. a click in another direction snaps things right back in to place. this is audible in music. or, if you like, listen to pink noise at 8khz only and alter one tweeter while leaving the other where it is. center it up by only working within a few clicks of T/A. then go to 10khz and see if it's good (it won't be). center it up. now go back to 8khz and see if it's still focused (it won't be). welcome to tradeoffs.


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## 07azhhr (Dec 28, 2011)

bikinpunk said:


> 0.02ms. change it a few times on the tweeters and there's a very audible difference.


I can certainly attest to this as well. I can change my TA for one tweet (mids and subs on mute) and hear it in a different location. They seem to move in a small square when I try this. They are playing from 6.3k and up so this is not because they are playing vocals.


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## benny (Apr 7, 2008)

I only have 0.1ms resolution with my TA, I'd like to play with a unit with finer adjustment


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## ErinH (Feb 14, 2007)

07azhhr said:


> I can certainly attest to this as well. I can change my TA for one tweet (mids and subs on mute) and hear it in a different location. They seem to move in a small square when I try this. They are playing from 6.3k and up so this is not because they are playing vocals.


yup. this is comb filtering at its finest. I can typically work in a 0.1 - 0.2 ms window and get it right... or get the tradeoff I'm willing to accept. T/A on tweeters isn't like it is for mids where you can hear the image move. with tweeters, the image may move... sure... but the coherency and focus of the sound is what _really_ changes with such little alteration of the delay time.


and truly, until you actually go sit in your car and listen for it, you'll never understand how much of an impact it has.


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## ErinH (Feb 14, 2007)

benny said:


> I only have 0.1ms resolution with my TA, I'd like to play with a unit with finer adjustment


you don't have to have as fine resolution as I do. give it a go.


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## 07azhhr (Dec 28, 2011)

bikinpunk said:


> but the coherency and focus of the sound is what _really_ changes with such little alteration of the delay time.


Yeah it certainly does sound different when these minor shifts happen. It is like uhm well ok, then well uhm no not really liking that, then wtf and then back to AHHHHHHHHH that sounds nice. 

And yeah with the mids it seems more of it is together, then separating, then separating more and more. Then leave the moved ono there and do the other side and it will join the first moved one. The tweets seem to only move in that small square but stay relatively close to the origional location.


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## therapture (Jan 31, 2013)

I won't go into details, but I used a simple method to get a baseline for the initial TA settings. Just measure your distances and then plug them in, converting the distance into time, based on the speed of sound at sea level.

Like minibari noted, the sub is furthest away from me, and equidistant to either mid, so it's "0" on TA. The right mid is next furthest, so it gets a delay set that is the *differential* between it and the sub's distance (I turned off the left mid while doing this). The speed of sound is constant and doesn't care if it's from a sub or a mid, so the trick is to get both sound waves to arrive at my head at the same time, and I tweaked the TA on the right mid until I got the best midbass and the sub was not localizable as behind me (upfront bass).

Then I take the difference between the left and right mid, convert to ms, and set left side to that, and turn it on of course. I already had phase and polarity well set, and this got me a solid center right off the bat, some may need to try swapping phase/polarity to get the best midbass/sub response. I previously had swapped polarity on the sub and phase on the mids until I had maximum midbass.

After the intial settings, I only had to adjust either side as little as .01 and no more than .1 !!! Careful intial measuring got me close! I then had to work on level balancing a bit to get some highs sorted out, but that's another issue.

End result, a very well defined, crisp, center image. It actually surprised me how good it was. -ps: don't make fun of my sketch, I thought it would illustrate my reasoning.


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## mooch91 (Apr 6, 2008)

therapture said:


> I won't go into details, but I used a simple method to get a baseline for the initial TA settings. Just measure your distances and then plug them in, converting the distance into time, based on the speed of sound at sea level.
> 
> Like minibari noted, the sub is furthest away from me, and equidistant to either mid, so it's "0" on TA. The right mid is next furthest, so it gets a delay set that is the *differential* between it and the sub's distance (I turned off the left mid while doing this). The speed of sound is constant and doesn't care if it's from a sub or a mid, so the trick is to get both sound waves to arrive at my head at the same time, and I tweaked the TA on the right mid until I got the best midbass and the sub was not localizable as behind me (upfront bass).
> 
> ...


I always thought you T/A'ed to a single speaker as reference, i.e., the furthest one. Your method T/A'ed right mid to sub then left mid to right mid.


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## benny (Apr 7, 2008)

bikinpunk said:


> you don't have to have as fine resolution as I do. give it a go.


Oh, I have. I just want/need a better processor setup :laugh:


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## therapture (Jan 31, 2013)

mooch91 said:


> I always thought you T/A'ed to a single speaker as reference, i.e., the furthest one. Your method T/A'ed right mid to sub then left mid to right mid.


The left and right sides are totally equal pathlengths to the sub. It just seemed to work well that way, I figured that the mids would have similar response in relation to the sub because of that. If I TA both mids to the sub, that defeat the center image, since there would be no delay between the mids at all, and both would play at the same time (no delay in relation to each other, which would be just like a stock stereo with no TA) and arrive at my ears at different times. Using the right mid or left mid I assume would have no difference in the intial matching, as far as using a single one to TA to the sub. The distance differential is what matters as far as TA goes for a stereo channel. We are not trying to make a stereo pair out of a single mid and the sub.

And my results are solid, I have a great center image! And solid midbass, with a sub that is integrating nicely as long as I don't go knob happy on the remote.


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## mooch91 (Apr 6, 2008)

therapture said:


> The left and right sides are totally equal pathlengths to the sub. It just seemed to work well that way, I figured that the mids would have similar response in relation to the sub because of that. If I TA both mids to the sub, that defeat the center image, since there would be no delay between the mids at all, and both would play at the same time (no delay in relation to each other, which would be just like a stock stereo with no TA) and arrive at my ears at different times. Using the right mid or left mid I assume would have no difference in the intial matching, as far as using a single one to TA to the sub. The distance differential is what matters as far as TA goes for a stereo channel. We are not trying to make a stereo pair out of a single mid and the sub.


Sorry, I meant difference in distance from your listening position to reference point. So if sub is at 185, left is at 50, and right is at 140, I thought physical measurement-based delays would be 185-185=0 for the sub; 185-140=45 for the right; and 185-50 = 135 for the left mid.


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## therapture (Jan 31, 2013)

mooch91 said:


> Sorry, I meant difference in distance from your listening position to reference point. So if sub is at 185, left is at 50, and right is at 140, I thought physical measurement-based delays would be 185-185=0 for the sub; 185-140=45 for the right; and *185-50 = 135 for the left mid.*



The 185-50 is not needed, take my head out of the equation, and EITHER mid is the SAME distance from itself to the sub. You have to use the right mid as initial delay because it is the furthest from you, and you want to get the right mid and the sub sound wave at your head at relatively the same time for best overall response and "upfront bass". Since the left mid is closer, you have to delay it MORE to make it arrive at your head at the same time, and therefore you use additional delay on it, in relation to the right mid, so that you steer your focal point/image to the center. Does that make sense?

I hope one of the experts can weigh in on this. I think I even confused myself trying to explain hahah...


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## mojozoom (Feb 11, 2012)

My sub is furthest away, but I found best results by flipping the polarity of the sub and then delaying it. I left the right mid at zero delay.

It wasn't my first choice on alignments, but it works. I'm sure that I'll smoke a turd in hell for not delaying everything in relation to the sub, but the bottom line is that I needed more delay than the 3sixty.2 could officially give (I needed over 6' of delay and it's designed for 5' max delay).


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## stryke23x (Jun 22, 2007)

One of the easiest tricks to get time alignment correct is to reverse the polarity on one of the drivers. When they are time aligned properly, there will be a deep notch at the crossover point because they are out of phase. Adjust in small increments up and down taking measurements until you see the deepest and most defined notch. Then flip polarity back where it should be and they should sum nicely.

You can also time align nicely by looking at the impulse response. Measure and adjust so the impulses all line up. This is easier between mids and tweeters than the subs as the shape of the impulse changes based on frequency so it is a little harder to see in the bass frequencies.


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## MarkZ (Dec 5, 2005)

bikinpunk said:


> 0.02ms. change it a few times on the tweeters and there's a very audible difference. i showed this to a new guy yesterday and he understood what I meant.
> 
> with subs, it's different. it takes a good deal of delay (ie: a whole lot more than 3 or 4 clicks @ 0.02ms) to notice any appreciable difference. I can typically move the relative* sub delay in 45 degree increments before I notice a real difference.
> 
> ...


I assume you're doing all this with your head stapled to the headrest?


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## MarkZ (Dec 5, 2005)

benny said:


> Oh, I have. I just want/need a better processor setup :laugh:


That kind of T/A resolution is unnecessary, but it seems like most of the people in this thread need processors with phase adjustments. 

Another thing to keep in mind is that 0.0227 is the lowest increment you can actually have for 16/44.1. If your processor says it goes down to 0.01, it's lying. [or it's interpolating, which should probably be avoided...].


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## cyberdraven (Oct 28, 2009)

In my experience, TA for subwoofers in cars doesnt help at all. 

Low frequencies are long. Try to TA your tweeter for 0.3ms and you'll definitely see the difference. Try TA 0.3ms on your mids and still noticeable but not as pronouced as your tweets. Finally, try TA 0.3ms on your subwoofer and tell me if there's significant change.

The key to tune subwoofers is to create a perfect handshake between the mids and sub. This is the only way for the sub to completely "disapear" and blends where the soundstage is.

To get that much needed handshake, you need to:
1. Have the midbass level at your crossover reqion mimic the subwoofer level at your crossover region. 

In typical cars, you'll find the low frequencies upfront but noticeably lacking. Once you increase the level of the sub, you'll hear it behind and that sucks! If you encounter this issue, play some tracks and turn-off your sub. If you cross your mids at 63hz, play close attention to 200hz below. You will notice that the mids are rolled-off at these levels. Boost it a little bit then until you get the tonality, then bring back the sub at HIGHER levels. Voila! you'll have a disapearing sub with upfront bass like before but now at higher low freq levels.

2. Crossover. Just like tweets and mids, play with the crossover. No hard or fast rule on where you set it, just make sure there's no cancellation or peaks at the crossover region.

3. Phase. For me this is the most important. Play with it and see what suits best. 

Just an interesting observation, in ALL cars ive listened to that has fantastic lows, upfront bass, they always have something in common- phase coherent. I play a pink noise with a bandwith limit of 40-80hz with the sub in reverse polarity and it was damn DEAD quiet, no sound at all, 0db. Thats how phase coherent those system is, complete cancellation if you reverse one of the drivers.

Thanks

Paeng


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## therapture (Jan 31, 2013)

bikinpunk said:


> yup. this is comb filtering at its finest. I can typically work in a 0.1 - 0.2 ms window and get it right... or get the tradeoff I'm willing to accept. T/A on tweeters isn't like it is for mids where you can hear the image move. with tweeters, the image may move... sure... but *the coherency and focus of the sound is what really changes with such little alteration of the delay time.*
> 
> 
> and truly, until you actually go sit in your car and listen for it, you'll never understand how much of an impact it has.


I see what you are saying, I think...I noticed my tweets would go majorly hot on one side, with very small adjustments in TA. I was confused because I was equating this with loudness, and I think that is the wrong way to look at it. I find that small, .01 changes affect the high ranges tremendously, and I was making too large of an adjustment on the TA, where I have now found that I can tune using small .01 increments and get noticeable changes in sharpness and definition of the image. Combined with some level matching, I have found a new level of SQ.


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## therapture (Jan 31, 2013)

cyberdraven said:


> 3. *Phase.* For me this is the most important. Play with it and see what suits best.
> 
> Just an interesting observation, in ALL cars ive listened to that has fantastic lows, upfront bass, they always have something in common- phase coherent. * I play a pink noise with a bandwith limit of 40-80hz with the sub in reverse polarity and it was damn DEAD quiet, no sound at all, 0db.* Thats how phase coherent those system is, complete cancellation if you reverse one of the drivers.
> 
> Paeng


If I reverse my sub phase 180 degrees using the 3sixty.3's GUI, it sounds like the sub has been turned off, does this mean I appeared to have lucked into a decent combination via my several weeks of tuning? I would like to hear a real life SQ car, up close, I bet I could learn alot from it.


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## MarkZ (Dec 5, 2005)

I've found the exact opposite of everything you guys are saying.  I'm actually shocked and bewildered that you guys are experiencing what you're experiencing. I thought it was fairly well-known that delay at high frequencies is not really accomplishing much, and that delay at low frequencies was a big deal.... precisely for the same reasons you guys are stating.

Look, if you delay your tweeter by 0.3ms, you're not actually impacting phase in any common-sense way. It's the equivalent of shifting one speaker by one wavelength at about 3kHz. At 6kHz, you're now shifting by multiple wavelengths.

If you delay your tweeter by much smaller increments, now you're shifting phase in a more common sense region (fractions of a wavelength), but you're doing the same exact thing simply by moving your head an inch to the right or left. Time alignment on tweeters makes sense if you implant a bar into your cranium and bolt it to the ceiling of your car when you get in. 

Also, relative timing doesn't impact localization at these frequencies. Tweeters are sensitive to ILD, not ITD.

I'm not saying you're not hearing a difference. Of course you are! But the difference is going to be way more dependent on head movement than at lower frequencies, where the wavelengths are longer.

I suspect that some of you guys need to play with your crossovers more than you're doing. Crossovers will usually solve your phase incoherence issues if you can independently adjust point, Q, and polarity! I promise!


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## minbari (Mar 3, 2011)

^^^^ I agree here too. if you shift a tweeter freq by one whole wavelength, what have you accomplished? you delayed it in such a way that it sounds exactly the same. since it only takes a few tenths of a milisecond to do that, T/A on tweeters in the least important.


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## ErinH (Feb 14, 2007)

MarkZ said:


> I've found the exact opposite of everything you guys are saying.  I'm actually shocked and bewildered that you guys are experiencing what you're experiencing. I thought it was fairly well-known that delay at high frequencies is not really accomplishing much, and that delay at low frequencies was a big deal.... precisely for the same reasons you guys are stating.
> 
> Look, if you delay your tweeter by 0.3ms, you're not actually impacting phase in any common-sense way. It's the equivalent of shifting one speaker by one wavelength at about 3kHz. At 6kHz, you're now shifting by multiple wavelengths.
> 
> ...



Mark, first off, tell me if you have no desire to try I've mentioned above. If you don't, there is no sense in us arguing this because until you hear what I'm saying, you won't understand that it's true. That said, I'll explain my point one more time.




As for your reply, yes, ILD & ITD (as well as IPD) are all measured and quantified realities. I never said either didn't play here. In fact, if you ask anyone I help out they'll tell you the first thing I mention is ILD & ITD. IOW... yes, we got it. 

Now, when you say localization, I'm assuming you mean the same thing I do: placement on the stage. For example, TA & ILD adjustments between right and left speakers that are at different distances from you are adjusted so you put the center in the center of the soundstage, rather than having sounds bunched up to your near side speakers.

The issue isn't purely localization, however. The issue is relative phase at the listening position. And, yes, without a doubt T/A impacts that phase because - as I stated previously - you're altering the combing pattern. It doesn't take only 0.027ms increments to tell this. And yes, moving your head can have the same affect, though I find getting proper TA setup to be more important because I'm not Stevie Wonder driving with my head all over the place and if I'm checking mirrors or looking back, I'm not worried about the soundstage. It's a car. I don't expect there to be even distribution throughout the cabin. 

No one said (at least I didn't) ILD & ITD are to be disregarded. In fact, I said the opposite. Mids are the most noticeable in terms of localization. Tweeters are much less so, again, in terms of _localization_. But when you're talking amplitude via the combing pattern adjustments, it's a different story. With sub and midbass, where the wavelength is longer, *for me* it's harder to tell differences in location in small doses of time alignment.


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## therapture (Jan 31, 2013)

I am not having issues, my rig sounds great. I don't run any delay on my sub, and my phase/polarity is great. I am loving this pursuit of SQ, I never, ever had the "upfront bass" that I have now. I didn't even know it could be that way until a couple months ago.




MarkZ said:


> I've found the exact opposite of everything you guys are saying.  I'm actually shocked and bewildered that you guys are experiencing what you're experiencing. I thought it was fairly well-known that delay at high frequencies is not really accomplishing much, and that delay at low frequencies was a big deal.... precisely for the same reasons you guys are stating.
> 
> Look, if you delay your tweeter by 0.3ms, you're not actually impacting phase in any common-sense way. It's the equivalent of shifting one speaker by one wavelength at about 3kHz. At 6kHz, you're now shifting by multiple wavelengths.
> 
> ...


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## MarkZ (Dec 5, 2005)

bikinpunk said:


> Mark, first off, tell me if you have no desire to try I've mentioned above. If you don't, there is no sense in us arguing this because until you hear what I'm saying, you won't understand that it's true. That said, I'll explain my point one more time.
> 
> 
> 
> ...


Erin, I've done exactly what you've done. Many times. [I was joking about "you crazies" having single sample resolution... you know I use a car PC and have it too...]

Also, I didn't mean to imply that localization is the only issue here. Actually, I didn't spend much time talking about localization. The issue here is phase coherence and its impact on the FR. I acknowledge that you guys are changing phase coherence by adding delay, but my point is that you're changing it by the same amount simply by moving your head. Stevie Wonder head movements aren't necessary... normal routine head movements, going over bumps, etc will move your head a quarter wavelength or more at the frequencies we're talking about.

I think some of you guys are barking up the wrong tree here. Just because you can _hear_ a change doesn't mean you can adjust it to achieve a _consistent_ change. You don't have that kind of precision. And that all has to do with the fact that the wavelengths are so short. As soon as adjustments begin to approach the intrinsic variance that occurs due to head movements and what not, those adjustments start to have less impact. It's analogous to trying to tweak a passive crossover to perfection when you're always fighting the effects of power compression.


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## ErinH (Feb 14, 2007)

I never really understand the head movement argument. If my head is relatively stationary (ie: I'm driving or at a meet) then it's moot. It's brought to the table as an argument that doesn't have any real world impact; if I'm driving and hit a bump my sense of connection to the music or critical listening is abbreviated. If I'm moving my head for anything then my focus is off the music for that moment. Maybe I'm the only guy who doesn't move his head around while he's driving. Which is fine, because I can tune for my listening position and you other guys have to deal with the issues you get when you move your head.


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## Mic10is (Aug 20, 2007)

bikinpunk said:


> I never really understand the head movement argument. If my head is relatively stationary (ie: I'm driving or at a meet) then it's moot. It's brought to the table as an argument that doesn't have any real world impact; if I'm driving and hit a bump my sense of connection to the music or critical listening is abbreviated. If I'm moving my head for anything then my focus is off the music for that moment. Maybe I'm the only guy who doesn't move his head around while he's driving. Which is fine, because I can tune for my listening position and you other guys have to deal with the issues you get when you move your head.


LIAR!!!
you move your head all the time when listening, usually followed by the word "SQUIRREL!!!"


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## highly (Jan 30, 2007)

It appears then that what's needed is a less compliant seatbelt and safety restraint. Maybe try a 5-point harness and a Hans device?


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## ErinH (Feb 14, 2007)

highly said:


> It appears then that what's needed is a less compliant seatbelt and safety restraint. Maybe try a 5-point harness and a Hans device?


I'm developing a laser system that keeps track of your forehead and alters the arrival time based on that. In real time. No,.... NO. IN FUTURE TIME!


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## minbari (Mar 3, 2011)

bikinpunk said:


> I'm developing a laser system that keeps track of your forehead and alters the arrival time based on that. In real time. No,.... NO. IN FUTURE TIME!


lol, while you are at it, can it automatically adjust for other phenomena like power compression?


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## ErinH (Feb 14, 2007)

Mic10is said:


> LIAR!!!
> you move your head all the time when listening, usually followed by the word "SQUIRREL!!!"


That would explain a lot, actually. Wish my master would fill the water bowl more often.


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## BuickGN (May 29, 2009)

Lol. My biggest problem is leaning to the right by accident when tuning, probably because the laptop sits there. I get it perfect only to find that I've been leaning the whole time and everything is off when I sit straight up. The only positive is I tend to lean toward the right as I get tired but by that time I'm turning the music down or off since it makes me more sleepy. The only thing worse is getting a near perfect tune and realizing the factory HU somehow got bumped and I tuned with the balance not centered or the bass turned up. 

I'm enjoying this thread.


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## MarkZ (Dec 5, 2005)

bikinpunk said:


> I never really understand the head movement argument. If my head is relatively stationary (ie: I'm driving or at a meet) then it's moot. It's brought to the table as an argument that doesn't have any real world impact; if I'm driving and hit a bump my sense of connection to the music or critical listening is abbreviated. If I'm moving my head for anything then my focus is off the music for that moment. Maybe I'm the only guy who doesn't move his head around while he's driving. Which is fine, because I can tune for my listening position and you other guys have to deal with the issues you get when you move your head.


I guarantee your head moves at least a quarter of an inch here and there while driving. It happens naturally as a consequence of centrifugal force.

And I didn't pull that quarter inch number out of my ass.  That's the length of 0.02 ms delay.

If you sit in a slightly different position in the car each time (mostly on left cheek, mostly on right cheek, left knee up a little, left leg extended, left arm on window shelf, right arm on center console, etc), your head is also going to be in a slightly different position each time. And if your wife ****s with your seat position, then all bets are off.

Do you know how easy car audio would be if we could position our heads in the same EXACT location every time? We could implement electronic echo cancellation, noise cancellation, deconvolution, etc. It would be SWEET.


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## ErinH (Feb 14, 2007)

You're right. I'm wrong. 


/cycle


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## MarkZ (Dec 5, 2005)

bout ****in time.


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## therapture (Jan 31, 2013)

BuickGN said:


> Lol. My biggest problem is leaning to the right by accident when tuning, probably because the laptop sits there. I get it perfect only to find that I've been leaning the whole time and everything is off when I sit straight up. The only positive is I tend to lean toward the right as I get tired but by that time I'm turning the music down or off since it makes me more sleepy. *The only thing worse is getting a near perfect tune and realizing the factory HU somehow got bumped and I tuned with the balance not centered or the bass turned up. *I'm enjoying this thread.



LoL - I did that once with balance to the left +1 and bass +2.....had to slap myself when I discovered I did that...


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## Hanatsu (Nov 9, 2010)

BuickGN said:


> Lol. My biggest problem is leaning to the right by accident when tuning, probably because the laptop sits there. I get it perfect only to find that I've been leaning the whole time and everything is off when I sit straight up. The only positive is I tend to lean toward the right as I get tired but by that time I'm turning the music down or off since it makes me more sleepy. The only thing worse is getting a near perfect tune and realizing the factory HU somehow got bumped and I tuned with the balance not centered or the bass turned up.
> 
> I'm enjoying this thread.


LOL. Same here, always leaning to the right unconsciously when tuning.

Sent from my Samsung Galaxy 3 via Tapatalk.


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## stryke23x (Jun 22, 2007)

Time alignment between drivers on the same side is much more critical than time alignment from left to right or from fronts to the sub. As a general rule time aligning the left and right to the drivers seat is used to move the image in front of the driver. Without it you don't have a good stereo image. The drivers side arrives first and appears dominant in the system. Getting the two sides to arrive at the same time restores a good center image. Matching the levels then finishes it off. This isn't too particular to distance or delay, it just has to be close. You can move your head back and forth 12" and it won't affect the image much. Time alignment to 1/10 of a ms is plenty accurate in this case.

The time alignment between mid/tweeter on the same side is more critical. Especially in cases where the distance between them is greater. You can have your mids down low on the doors and tweeters up on the pillars and still get good results as long as they are properly time aligned. The farther the distance, the more particular the results are to movement of your head. If crossing over at 3KHz, the wavelength is only 4.5" long. A path length difference of 2.75" puts the drivers out of phase at their crossover point. If the drivers are close to one another, it takes a massive head movement to mess with that. That is why it is best to have drivers close to one another. At 3KHz, tiny adjustment in terms of time delay can have a much more significant affect on response. That is where you might need to be into 1/100ths of a ms to get it right.


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## Dillyyo (Feb 15, 2008)

MarkZ said:


> I guarantee your head moves at least a quarter of an inch here and there while driving. It happens naturally as a consequence of centrifugal force.
> 
> And I didn't pull that quarter inch number out of my ass.  That's the length of 0.02 ms delay.
> 
> ...


FWIW I can move my had several inches in any direction, up and down and I never lose such levels of phase coherence that I notice that drastic of a change in stage or output.


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## MarkZ (Dec 5, 2005)

Dillyyo said:


> FWIW I can move my had several inches in any direction, up and down and I never lose such levels of phase coherence that I notice that drastic of a change in stage or output.


Which proves that relative phase between L & R tweeters doesn't really matter.


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## ZAKOH (Nov 26, 2010)

If subwoofer is grossly out of phase with front speakers, adjusting time alignment or phase can make an audible difference. If it's just a little out of phase, it can be difficult to find the right time alignment setting by ear.


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## therapture (Jan 31, 2013)

MarkZ said:


> Which proves that relative phase between L & R tweeters doesn't really matter.


I was chasing phase on the tweets, never finding a happy setting, when in fact I was supposed to be fixing the issue with EQ balancing. Once I started down that road I cured my tweeter issue.


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## ErinH (Feb 14, 2007)

MarkZ said:


> Which proves that relative phase between L & R tweeters doesn't really matter.




There is an audible difference in relative phase. Doesn't really matter is a very relative term apparently.


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## MarkZ (Dec 5, 2005)

Dillyyo says there isn't. 

It's worth noting that for a lot of program material, the stereo correlation >1kHz can be very small. Between that and the head position issue, it's hard to argue that L/R phase coherence is as important than phase coherence at the crossover.


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## Dillyyo (Feb 15, 2008)

MarkZ said:


> Which proves that relative phase between L & R tweeters doesn't really matter.


I think maybe it matters more on it's own than it does in a complete system. I have noticed differences when setting up my system and setting TA/phase on just the tweeters, just as Erin said. I just think when the rest of my system is phase coherent that such head movements make no real differences. Maybe I'm just lucky that my vehicle allows this behavior, but I've never experienced such drastic changes in any of my car set ups.


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## ErinH (Feb 14, 2007)

MarkZ said:


> Dillyyo says there isn't.
> 
> It's worth noting that for a lot of program material, the stereo correlation >1kHz can be very small. Between that and the head position issue, it's hard to argue that L/R phase coherence is as important than phase coherence at the crossover.


I don't disagree with you in entirety. My point is one of compromises. Let's say I concede and agree that I move my head even 40% of the time from where I tuned the tweeters to sound most in phase. That means 60% of the time I still enjoy that sweet spot. Car audio ultimately boils down to tradeoffs. Luckily I don't move my 40% of the time so the tradeoff isn't dramatic.


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## MarkZ (Dec 5, 2005)

Dillyyo said:


> I think maybe it matters more on it's own than it does in a complete system. I have noticed differences when setting up my system and setting TA/phase on just the tweeters, just as Erin said. I just think when the rest of my system is phase coherent that such head movements make no real differences. Maybe I'm just lucky that my vehicle allows this behavior, but I've never experienced such drastic changes in any of my car set ups.


But delay and head movements are doing the *same exact thing*. That is why some DSP manufacturers represent their delay values in meters rather than in seconds. The speed of sound is (roughly) constant, so there's an easy transformation going from one to the other.

If you delay your left tweeter by 0.1ms, you're doing the same thing you'd be doing if you moved it away from you by 3.5cm (ignoring reflections and whatnot). Moving the tweeter away from you 3.5cm is equivalent to moving YOU away from the tweeter by 3.5cm. So when you say you hear a difference delaying your tweeter by 3.5cm, it doesn't make sense that you don't also hear a difference moving your head by 3.5cm.

The exception to this is if your speakers are configured so that they are very close to each other. For example, in a coaxial arrangement, delay of the tweeter alone by 3.5cm is possible, but moving your head by 3.5cm moves both the tweeter and the woofer. This is (part of) the reason why I said that L/R delay at high frequencies is less effective than delay around the crossover. Stryke23x actually said this before I did. 



bikinpunk said:


> I don't disagree with you in entirety. My point is one of compromises. Let's say I concede and agree that I move my head even 40% of the time from where I tuned the tweeters to sound most in phase. That means 60% of the time I still enjoy that sweet spot. Car audio ultimately boils down to tradeoffs. Luckily I don't move my 40% of the time so the tradeoff isn't dramatic.


Right, but it's also worth keeping in mind where all the variance comes from, and if there's something that's high variance then trying to achieve precision doesn't make any sense. We know that moving your head half an inch is going to have an impact on high freq phase relationships, but not so much when it comes to low freq phase relationships. Therefore, if you know that 40% of the time you're ****ing up your phase relationship at high freqs, and 0% of the time you're ****ing up your phase relationship at low freqs, then it makes more sense to focus on precision at low freqs. Which is one reason I said that delay is more important at low freqs... [the other reason is the localization issue]

And don't give me this ******** that you don't bob your head back and forth when you have Seals and Croft cranked. Someone was telling me you were jamming out to this the other day...

Tommy Seebach Band - apache - YouTube


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## Dillyyo (Feb 15, 2008)

MarkZ said:


> But delay and head movements are doing the *same exact thing*. That is why some DSP manufacturers represent their delay values in meters rather than in seconds. The speed of sound is (roughly) constant, so there's an easy transformation going from one to the other.
> 
> *If you delay your left tweeter by 0.1ms, you're doing the same thing you'd be doing if you moved it away from you by 3.5cm (ignoring reflections and whatnot). Moving the tweeter away from you 3.5cm is equivalent to moving YOU away from the tweeter by 3.5cm. So when you say you hear a difference delaying your tweeter by 3.5cm, it doesn't make sense that you don't also hear a difference moving your head by 3.5cm.*
> 
> ...


I understand what you are getting at and I agree. I likely don't experience this because my mid-ranges are very close to my tweeters, while my MB, MR and TW are also all on the same plane. This is basically what I was inferring when I said all of my speakers are in phase coherence, but that was with the qualifier that my speakers are situated the way they are.


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## MarkZ (Dec 5, 2005)

IMO, some of these issues illuminate just how advantageous coaxials are.


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## 14642 (May 19, 2008)

MarkZ said:


> I guarantee your head moves at least a quarter of an inch here and there while driving. It happens naturally as a consequence of centrifugal force.
> 
> And I didn't pull that quarter inch number out of my ass.  That's the length of 0.02 ms delay.
> 
> ...


Precisely. fortunately, our ears and brains use midrange sounds, primarily, to determine the location of sounds. That makes tuning systems relatively simple. Phase has to be correct in the midrange and less correct at very low frequencies and very high frequencies. In fact, if you think about this in terms of group delay, a flat group delay isn't necessary, but a smooth one is. Abrupt changes in timing are the issue.


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## ErinH (Feb 14, 2007)

Seriously, is there an echo in here or is it me? Lets see how many people can say the same thing in a different way. Ready? GO!


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## MarkZ (Dec 5, 2005)

bikinpunk said:


> Seriously, is there an echo in here or is it me? Lets see how many people can say the same thing in a different way. Ready? GO!


My turn!

_It is used primarily in real time, all the speakers time concerns were secondary, humble advice, as well as the first to correct in response to power away. Will be divided into parts, so if there are steps, the progressive solution, but in my ears, only the sound of the hard disks found in the settings area._

[cajunner's post passed through 8 sequential Bing translators...]


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## 14642 (May 19, 2008)

OK, another one for the echo chamber:

1/4" doesn't matter.


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## MarkZ (Dec 5, 2005)

Wear headphones.


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## ErinH (Feb 14, 2007)

Quit car audio.


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