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Thread: Let's talk about time alignment!

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    Noob Fricasseekid's Avatar
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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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    Noob Keele81's Avatar
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    Re: Let's talk about time alignment!

    Quote Originally Posted by Fricasseekid View Post
    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. 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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    Big Daddy chad's Avatar
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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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    Noob Fricasseekid's Avatar
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    Re: Let's talk about time alignment!

    What does SMAART do that REW does not Chad?


    Sent from my Springfield XD with love!

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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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    Big Daddy chad's Avatar
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    Re: Let's talk about time alignment!

    Quote Originally Posted by Fricasseekid View Post
    What does SMAART do that REW does not Chad?


    Sent from my Springfield XD with love!
    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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    Noob Fricasseekid's Avatar
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    Re: Let's talk about time alignment!

    Quote Originally Posted by chad View Post
    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.


    Sent from my Springfield XD with love!

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    Big Daddy chad's Avatar
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    Re: Let's talk about time alignment!

    Lol. PHANTOM POWER

    Wtf is adderal?

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    Noob Fricasseekid's Avatar
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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.


    Sent from my Springfield XD with love!

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    Big Daddy chad's Avatar
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    Re: Let's talk about time alignment!

    That shit would send me through the roof.

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