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Let's talk about time alignment!
Lets talk about T/A (time alignment)!
I am currently aware of 4 ways to adjust T/A.
1&2. By ear
1. Use pink noise and listen for the Doppler effect while adjusting the T/A. Try to get the speaker right at one of the first peaks or troughs as the phase change.
2.Use music and listen for the center image to come into focus. When the sound waves are out of phase the image will sound wide and when T/A is in it's proper place everything should be in phase and focus in the center.
3. Measure the distance from each speaker to the listening position, then figure the difference between each speaker and the speaker that is furthest away. Adjust your T/A appropriately based on measured distance and the speed of sound.
4. Use software such as REW to measure an impulse response and align each drivers response to the base driver (the one with the most latent impulse).
Pros & Cons
1&2.
Pros:
-This is for music. So in the end its what you hear that really matters!
-This can take into account for reflection and diffraction going on inside the vehicle that measurements cant attain.
Cons:
-Its not easy. Listeners fatigue and other factors can reduce the sensitivity of our hearing.
-Psycho-acoustics come into play. Our ears can be deceiving!
-Sometimes its easy to hear the difference in two similar drivers on the left and right, but much more difficult when aligning say, a midbass to a midrange on the same side.
- You must find the peak in the center or in the Doppler effect with these two methods. This can be very difficult when the drivers are already closely aligned. It helps to be able to listen for the rising or falling phase on either side of an acoustic peak or trough. But when the drivers are already close to one of those peaks or troughs you don't have a phase change in both directions to judge symmetry.
3.
Pros:
-By far the easiest method
-Very little margin of error
-Gets you pretty close.... Maybe?
Cons:
-Does not take into account reflection, diffraction, and other vehicles acoustic issues that can effect the staging and image.
-Metal tape measure tongue can get sucked into a strong magnet and damage driver cone. (personal experience)
4.
Pros:
-Probably the most accurate method
Cons:
-Requires extra equipment such as: measuring devices that can get costly, extra cables, a computer and software.
-Requires research time. One must gain the knowledge of the software used to do this properly.
-Requires Mic and PC calibration.
So? Which method do you use?
I used to believe that T/A was black in white. I don't think i believe that anymore. I am coming to realize that T/A (like every other aspect of car audio tuning) is a game of give and take. Sometimes that gray area can be quite large!
So what kind of sacrifices are made for a tighter sound stage?
In what cases would you allow your T/A to be slightly off in order to gain elsewhere?
Do you even believe it is possible to dial in T/A 100% perfect?
How do you know it is perfect (please don't use "because my system sounds great" as an example)?
Do you believe the "impulse response" method can account for a car's acoustical issues as well adjusting by ear?
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Re: Let's talk about time alignment!
Quote:
Originally Posted by
Fricasseekid
Lets talk about T/A (time alignment)!
-Metal tape measure tongue can get sucked into a strong magnet and damage driver cone. (personal experience)
I knew I couldn't have been the only one in the world to manage to do this, thanks for being real. :thumbup: I've only used measuring method & auto eq on pioneer so I can really help any. I started using twine or yarn & a sharpie to measure with after I pulled a similar fuck up. I label them with a piece of tape so I can carry all my twine/yarn pieces indoors with the ac to do actual measurement & any math.
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Re: Let's talk about time alignment!
4... I use SMAART.
The only other way is to measure, get it close, flip the polarity of one passband and null it out. And that's marginal.
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Re: Let's talk about time alignment!
What does SMAART do that REW does not Chad?
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Re: Let's talk about time alignment!
I'm no expert, and own none of the fancy measuring software. Physically measuring always leaves me with major phase issues, so that leaves me with "by ear". In the beginning,this was challenging, because my main focus was always on stage, then ending up with nasty tonality issues that I believe came from phase issues just like when I was measuring. The more I listened while I was adjusting in small increments, the more I learned the correlation between phase and tonality, and how much time allignment affected this. I can now get myself happy by ear.......but, I'm always retuning, just to torture myself and every few tunes I learn some more.......that being said, my time allignment settings are nowhere even related to the actual physical location of my drivers.......but when the old ears are happy, I don't argue.
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Re: Let's talk about time alignment!
Quote:
Originally Posted by
Fricasseekid
What does SMAART do that REW does not Chad?
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It is transform based.... real time. Works with plain-ol music.
So what is does id give you data from extrapolating differences in a closed loop system.... You feed the left channel the exact source you feed the audio and the right channel the mic. so it KNOWS what the system is getting versus what. Somehow REW does this but I'm not certain that it is a hardwired closed loop, you want this.
It is very user friendly as it is designed to be used in the field live.
Cons..... Fucking expensive.
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Re: Let's talk about time alignment!
Quote:
Originally Posted by
chad
It is transform based.... real time. Works with plain-ol music.
So what is does id give you data from extrapolating differences in a closed loop system.... You feed the left channel the exact source you feed the audio and the right channel the mic. so it KNOWS what the system is getting versus what. Somehow REW does this but I'm not certain that it is a hardwired closed loop, you want this.
It is very user friendly as it is designed to be used in the field live.
Cons..... Fucking expensive.
This is my current problem. I've read several how-tos for doing impulse response with REW. And they all sound something like what you just said. I think calibrating your comp sound board as some effect on it and I dint even know what sound card my shitty laptop has, and I'm missing a piece of equipment in the signal chain. All I have is a mic, usb ghost power, a laptop and the software.
I guess I'm just gonna have to pop an adderall and research the subject for a few hours and figure out exactly what I need to make it happen.
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Re: Let's talk about time alignment!
Lol. PHANTOM POWER
Wtf is adderal?
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Re: Let's talk about time alignment!
Lol, yeah. That's it.
Adderall is legal amphetamines that I take for my ADD. I dose up whenever I'm lethargic or embarking on a task which requires my concentration.
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Re: Let's talk about time alignment!
That shit would send me through the roof.
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Re: Let's talk about time alignment!
Fric tried to bait the guys on the facebook Q&A section with this same write up ... no one bit.
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Re: Let's talk about time alignment!
Quote:
Originally Posted by
chad
That shit would send me through the roof.
It's all in the dosage.
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Re: Let's talk about time alignment!
Quote:
Originally Posted by
PaulD
Fric tried to bait the guys on the facebook Q&A section with this same write up ... no one bit.
Isn't whistle blowing illegal?
Besides those guys need some tech write ups shoved down their throats!
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Re: Let's talk about time alignment!
I use my ears, put in a mono track (such as Don Cheskey speaking on a constant loop),close my eyes and start to turn the dial for each driver individually until it is centered. It has never failed me, and I have always had a tight as a frogs ass in water center image with very good staging detail.
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Re: Let's talk about time alignment!
I've been wondering how to fine tune my HU's T/A, I'm using the general "sedan" setting but it still feels off. I guess those mono Brubeck CD's will be of use after all. Though when you say you do each driver individually are you talking about using the balance and fad to isolate one driver at a time?
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Re: Let's talk about time alignment!
Quote:
Originally Posted by
chefhow
I use my ears, put in a mono track (such as Don Cheskey speaking on a constant loop),close my eyes and start to turn the dial for each driver individually until it is centered. It has never failed me, and I have always had a tight as a frogs ass in water center image with very good staging detail.
^This. Only I go one step further; after tuning the drivers per pairs, I dial them together (aka midbass with mids, then mids with tweeters, etc).
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Re: Let's talk about time alignment!
Actually to measure impulse ( time ) response you don't need a calibrated mic..
It's about receiving the impulse, not FR.. ;) And as long as you measure with a reference-signal, or multiple drivers at the same time ( per side, to get the biggest spike ) calibration is not needed since you're measuring time and not frequency..
I use Holm for my measurements with a Tascam US-122mkII usb soundcard and a Behringer ECM8000 mic.
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Re: Let's talk about time alignment!
Quote:
Originally Posted by
n_olympios
^This. Only I go one step further; after tuning the drivers per pairs, I dial them together (aka midbass with mids, then mids with tweeters, etc).
Exactly! :D
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Re: Let's talk about time alignment!
Nick, On my H701 I could mute or turn off each driver and play only one at a time, I believe most if not all units will allow that.
Nick O, if it does need to be fine tuned once its all turned back on then I will do a summed T/A.
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Re: Let's talk about time alignment!
Mic10is would add time alignment to his sub when competing ( up to 5 milliseconds ).
You are looking for a sound from a song you know intimately, that pleases you !
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Re: Let's talk about time alignment!
Quote:
Originally Posted by
Hic
Mic10is would add time alignment to his sub when competing ( up to 5 milliseconds ).
You are looking for a sound from a song you know intimately, that pleases you !
He did that with a sub upfront. When we did my car I could have as much as 10MS added to mine. At one point we were playing around and added 12+ ms to the fronts and had the image half way out the hood, it was just like listening in a tunnel...
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Re: Let's talk about time alignment!
You still have to remember that time allignment also plays the role of phase shifting. Delaying a sub can make it in total acoustical phase to the listener's position. I for one don't believe in the theory that says the sub (usually being the one further away from the listeners) should have 0 delay, and all the rest should tune to that. I'm not saying it can't happen, but it'll be due to the cabin size/shape, and the sub placing and angling.
Whatever works, man.
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Re: Let's talk about time alignment!
Quote:
Originally Posted by
n_olympios
Whatever works, man.
THAT^^^^^^
Every car is a different environment and presents different challenges. There is no cure all for every car, there are theories that can be put into place but every car will have its own problems/solutions
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Re: Let's talk about time alignment!
Somebody brought up this technique on Diyma and I tried it with fairly good success...at least it got me a good starting point:
1. Turn off all your channels except for the farthest driver and play pink noise
2. Starting with your next farthest driver, turn it on and reverse the phase 180°
3. Start adding t/a to this driver and listen for it to start cancelling out the original driver. In a perfect world, once the two drivers are in alignment, they should completely cancel each other out.
4. Once you've found the deepest trough, you are done. Switch the phase on this driver back to 0º and it should be in alignment with the source driver.
5. Repeat the steps with the next farthest driver.
As with any time alignment technique, it's a good starting point, but your ears will need to be the final judge.
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Re: Let's talk about time alignment!
Quote:
Originally Posted by
AL9000
As with any time alignment technique, it's a good starting point, but your ears will need to be the final judge.
I disagree, They are aligned or not.. Ears should be used for tonality imo.. :P
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Re: Let's talk about time alignment!
Quote:
Originally Posted by
AL9000
Somebody brought up this technique on Diyma and I tried it with fairly good success...at least it got me a good starting point:
1. Turn off all your channels except for the farthest driver and play pink noise
2. Starting with your next farthest driver, turn it on and reverse the phase 180°
3. Start adding t/a to this driver and listen for it to start cancelling out the original driver. In a perfect world, once the two drivers are in alignment, they should completely cancel each other out.
4. Once you've found the deepest trough, you are done. Switch the phase on this driver back to 0º and it should be in alignment with the source driver.
5. Repeat the steps with the next farthest driver.
As with any time alignment technique, it's a good starting point, but your ears will need to be the final judge.
That's the nulling I was speaking of, using pink noise is not the brightest thing to do unless it's heavily bandwidth limited.. man up and use a tone.
Quote:
Originally Posted by
WOOSEY
I disagree, They are aligned or not.. Ears should be used for tonality imo.. :P
Word to your mother.
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Re: Let's talk about time alignment!
I originally set T/A by ear using pink noise and familiar songs. I did something similar to what Al just posted and to the method posted on the first page using tones and a center image.
The result was promising, once I finally figured out that I needed to flip my passenger side full-range's polarity. I had a decent center image and strong left/right. But my center image was slightly to the left of where it should've been.
So last night for shits and giggles I redid all my T/A settings with a tape measure and then I confirmed/fine tuned those setting by ear. The results were so far from my original settings that its not even worth posting the numbers. The funny thing is that the image ended up about the same as before except my center was actually centered and I no longer needed to flip one of the midranges. In fact none of my driver polarities required swapping and my midbass felt more punchy. I also need to do a little more critical listening but it seems that I have more resolution in between center and left/right stage.
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Re: Let's talk about time alignment!
I've seen numbers from each side on equalizer with sliders that were completely different ( no mirror image ).
But sound was very nice to my ears
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Re: Let's talk about time alignment!
Quote:
Originally Posted by
Hic
I've seen numbers from each side on equalizer with sliders that were completely different ( no mirror image ).
But sound was very nice to my ears
Huh?
Are you talking about eq or t/a?
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Re: Let's talk about time alignment!
Quote:
Originally Posted by
WOOSEY
I disagree, They are aligned or not.. Ears should be used for tonality imo.. :P
Having the sound from all speakers reach your ears at the exact same time doesn't certify that the result is perfect. Phase coherence is necessary and only achieved through acoustical tests.
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Re: Let's talk about time alignment!
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Originally Posted by
n_olympios
Having the sound from all speakers reach your ears at the exact same time doesn't certify that the result is perfect. Phase coherence is necessary and only achieved through acoustical tests.
and with the right slopes... But then again, perfect phase is impossible in a vehicle...
When your drivers are aligned well, phase should be pretty good, since the impulses arrive at the same time.
You can always integrate all-pass filters for phase adjusting, not using ta for phase problems...
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Re: Let's talk about time alignment!
Quote:
Originally Posted by
chad
Word to your mother.
I just did... She looked pretty stupid when I said that... :D
Do you know her? She did some translating work for 10cc and Uriah heep a long time ago..
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Re: Let's talk about time alignment!
Quote:
Originally Posted by
Hic
I've seen numbers from each side on equalizer with sliders that were completely different ( no mirror image ).
But sound was very nice to my ears
I have never seen an EQ that was the same on both left and right that sounded very good.
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Re: Let's talk about time alignment!
Quote:
Originally Posted by
chefhow
He did that with a sub upfront. When we did my car I could have as much as 10MS added to mine. At one point we were playing around and added 12+ ms to the fronts and had the image half way out the hood, it was just like listening in a tunnel...
http://en.wikipedia.org/wiki/Precedence_effect
http://www.rane.com/par-h.html
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Re: Let's talk about time alignment!
Ok, I was messing with the T/A on my new HU, so I can have it set to match my car instead of using the default "sedan" setting. I wanted to give the measuring the distance from each driver to the desired listening position (Front Left in this case). From myh understanding I would measure the distance from the farthest driver from the desired listening position (Right Rear) and set the distance/delay to the measurement on the HU (57 inches in my case). You would then take a measurement of the next furthest driver (front right) and add the difference between the two to get the T/A for that driver. It was 55 inches which is 2 inches closer meaning I set it to 58 inches, correct?
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Re: Let's talk about time alignment!
Quote:
Originally Posted by
Hi-FiDelity
Ok, I was messing with the T/A on my new HU, so I can have it set to match my car instead of using the default "sedan" setting. I wanted to give the measuring the distance from each driver to the desired listening position (Front Left in this case). From myh understanding I would measure the distance from the farthest driver from the desired listening position (Right Rear) and set the distance/delay to the measurement on the HU (57 inches in my case). You would then take a measurement of the next furthest driver (front right) and add the difference between the two to get the T/A for that driver. It was 55 inches which is 2 inches closer meaning I set it to 58 inches, correct?
I think you should just measure and enter the distances in the HU, the processor does the calculating... ( A kenwood unit ? )
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Re: Let's talk about time alignment!
And make sure to report back how it turns out.
Most systems I've seen only need the differences entered, with the furthest driver remaining at 0".
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Re: Let's talk about time alignment!
Quote:
Originally Posted by
WOOSEY
I think you should just measure and enter the distances in the HU, the processor does the calculating... ( A kenwood unit ? )
The HU is a Pioneer FH-P5000MP from 2005, so I don't know how sophisticated her DSP is in that regard. The manual doesn't tell me a damn thing aside from how to adjust the settings. I'll try just inputting the difference and report back.
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Re: Let's talk about time alignment!
Well I set the T/A as woosey and Fric suggested and it solved the imaging issues I had been experiencing. The sound stage is definitely centered in front left of the car now, though it not as focused as I would have hopped I think that could be due to the lack of power my speakers are getting from the head units inbuilt amp. We'll see what happens when I get the amp installed.
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Re: Let's talk about time alignment!
Ee-Kew!!!
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