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Discussion Starter #62
The 2/3d view is simply frequency vs delay in ms.

If it's off the the L/R timing is incorrect. Correct this with T/A.

There can of course be other problems like crossovers.


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What is the best process for using TDA?
Should I mute everything but tweeters and align them, then add mids?
Or try to align entire left side and then right side and then align the two sides together?



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Before you continue on that path you should install HolmImpulse and setup your T/A with that. Then go back and check everything with TDA to see how it looks. Just for fun of course. =]
 

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Discussion Starter #65
You place microphone clamped between the seat and headrest. Don't be in the car, run all speakers at the same time. Full system, left and right sides + sub. There you'll see the complete time coherency of the system.

You could go left and right side only + sub too if you are troubleshooting for something.
 

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I actually have holmimulse, just haven't had time to learn how to use it.


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You place microphone clamped between the seat and headrest. Don't be in the car, run all speakers at the same time. Full system, left and right sides + sub. There you'll see the complete time coherency of the system.

You could go left and right side only + sub too if you are troubleshooting for something.

Start at with 0 time delay and try to "walk" it in from there? And assume that it would be the driver's side that needs delaying?
Do you try to align tweeter, then move to mid, then midbass, then sub?


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I had the sub muted.
I would start to look at AFR graph. Improving the frequency response of the selected channel (left or right) by EQ might make the time delay more smooth. Then test once more time and open DFR graph to define values of time alignment needed for every speaker. The goal is to optimize the system in the way when sound from different speakers will arive at the same time. I am talking here about impulse start (arriving start time), not peaks , in order to avoid pre-ringing and the low end. It is important for natural sounding of your system. For TW, mids and MB try to make DFR curve close to 0ms. For subwoofer - the sound should arrive simultaniosly with other speakers, not before. Typically it is much later for SW placed in a trunk, and even worse for a complicated box like 4. or 6. order bandpass.

What are TA settings for these graphs?
 

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... I am perplexed with TA and our beans.. What I mean is our "mic's" on our heads have two, not one, and they're several inches apart. This is the conundrum I'm dealing with concerning a measured TA tool verses ear alignment. Were it speakers very far away and more in-front, instead of car with wider speaker placement and short distances, I could fathom that a single mic point would be pretty darn spot on, but when drivers are so wide as they are in car and your ears are also relatively wide apart, how's it work?
About this, I will try tomorrow 2 different points, left / right ears with me in the car, just to see the difference.

So far I just did one point in front of the nose:


No manual Ta with ms8, but I'll play with different ms8 calibration too.
 

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Wow... That's your first try?!? I have spent HOURS trying to align and haven't gotten anything nearly that good. I'll post my current best later.


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Wow... That's your first try?!? I have spent HOURS trying to align and haven't gotten anything nearly that good. I'll post my current best later.


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Ms8 and APL, so it's really not me :D
But check that, left and right:





Sub could be better on both, i have somehting strange on the right woofer, and some ringing on the right tweeter?
I'll try some more with ms8 on/off and apl on/off.
 

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Yeah I know he is using the MS8 but that is still really impressive now that I have experienced how hard it is to get those frequencies to line up. Especially the sub, I am out of delay to add on my tweets and still like 20 seconds out on the sub. I must still not be doing something properly.
Ah, so you are using the APL already? And that is adding delay to specific frequencies, correct?
I haven't started using my APL yet and trying to do it just by TDA.



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Yeah I know he is using the MS8 but that is still really impressive now that I have experienced how hard it is to get those frequencies to line up. Especially the sub, I am out of delay to add on my tweets and still like 20 seconds out on the sub. I must still not be doing something properly.
Ah, so you are using the APL already? And that is adding delay to specific frequencies, correct?
I haven't started using my APL yet and trying to do it just by TDA.



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Yes it does fix the ir, but what part is due to ms8 and what part is due to APL, I should learn soon.
So you got your, don't wait, even in bad hands like mine it's really cool! :p
 

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Discussion Starter #75
I have to stress this:

DO NOT SIT IN SEAT WHILE MEASURING. DON'T TOUCH THE MICROPHONE.

Clamp it in headrest, in the middle where your head is normally. If you move the mic even an inch the measurement will be messed up. If you are aiming for repeatable results while correcting time coherency the mic must be absolutely stationary.

Elgrosso, The results you seeing on right side are probably due to destructive interference. I assume there's dips in the frequency response (AFR) at the same spots. Is this a 2 or 3-way? If it's a door mid it's perfectly normal. A small dedicated midrange should do better if placed optimally. Where is the crossovers? ;)
 

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Even if it is door installment of the mids, it does not explain the difference between left and right channels. Interesting to check FIR filters upload for the right channel. Wrong EQ by ms8? Look also on XO points and filter orders. Just to eliminate possible error source.

Can you repeat the measurement for the right side?
 

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I have to stress this:

DO NOT SIT IN SEAT WHILE MEASURING. DON'T TOUCH THE MICROPHONE.

Clamp it in headrest, in the middle where your head is normally. If you move the mic even an inch the measurement will be messed up. If you are aiming for repeatable results while correcting time coherency the mic must be absolutely stationary.
Ok that makes sense, will do next time (damn' I don't have a headrest :D)
But what about picking a "repeatable" point, that is closer to each ear?
Doesn't it make sense to use a point around left ear for left channel, and right ear for right channel ?


Elgrosso, The results you seeing on right side are probably due to destructive interference. I assume there's dips in the frequency response (AFR) at the same spots. Is this a 2 or 3-way? If it's a door mid it's perfectly normal. A small dedicated midrange should do better if placed optimally. Where is the crossovers? ;)
It's a 3 way, mids on dash, and the interferences here are near the cross over point: 800Hz/24db between woofer and midranges (even if it looks like 500Hz here).

I didn't "REW" this setup yet, but usually I have more a peak around there.

I re-did them this morning, so mic in hand I probably moved few mm (not inch)
right ear/right channel:

left ear/left channel:


But they are really different than yesterday, around the sub.
Maybe I had a different sub setting I don't remember.
Next measures will be more serious, here it was just to see how this works.
But probably nothing soon, big rain last few days, and my old car is a bit leaky... had to remove the gti to protect them :/
 
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