# Subwoofer time alignment?



## MrLister (Feb 17, 2006)

Any good tips on how to time align a sub woofer?


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## dkm201 (Nov 29, 2007)

Assuming the sub is the furthest speaker from your listening position, you'll want to time delay everything ELSE, not the sub...


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## MrLister (Feb 17, 2006)

Yea but I'm having a hard time figuring out by how much because unlike the front stage it's a lot tougher to listen to a setup disc and figure out the best center or front.


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## frankmehta (Jan 20, 2009)

im watching this closely. want to hear the gurus about this.


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## freemind (Sep 11, 2008)

What kind of deck are you using?

I use a Pioneer 860mp and it helps to do the sub alignment.

But the deck has the toys(but not all of them).


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## pjhabit (Aug 12, 2008)

Would T/A help you get away w/ a higher LP point, while still keeping the bass up front?


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## donkeypunch22 (Nov 5, 2008)

1. Measure distance from forehead to all speakers in meters (0.00 accuracy is more than enough).
2. Distance of farthest speaker (usually your sub) - distance of speaker to adjust
3. Divide by 343
4. Multiply by 1000
5. Answer is time delay in milisec
6. Listen and make small adjustments, I tend to delay the fronts/center a bit more (all by the same amount) than the math says to give the illusion of "bass up front." Also helps to have your midbass up front playing as low as possible and sub low passed at 24db/oct below 100hz (I tend to set it no higher than 75Hz). 


Hope that helps.


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## 14642 (May 19, 2008)

Bass up front depends much more on the response in the transition from bass to midbass and on woofer distortion and rattles than it does on time alignment. Shoot for a smooth transition from 60-160 Hz and between 6 and 9dB more bass than midrange. Then, once the bass sounds more like it comes from up front, adjust the delay for the rest of the front speakers to improve the bass up front illusion. Adjust all of the front speakers by the same increments. 

This is difficult to measure acoustically, because high frequencies are helpful in viewing the initial peak in the response. Also, the group delay in the sub's response, which is a function of the response roll-off is also difficult to measure. That's why setting the sub using the tape measure and making final adjustments by ear is the best and quickest way to do this part.


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## freemind (Sep 11, 2008)

Just look at that post count would ya?


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## OSN (Nov 19, 2008)

freemind said:


> Just look at that post count would ya?


Ah, more evidence for the 'Andy is trying to screw the public to make a quick buck' sentiment.


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## smgreen20 (Oct 13, 2006)

Here's a visual from the Eclipse manual if it helps any.


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## kunibert (May 11, 2009)

You have to calculate a bit, setting up by ears is extremely hard to do.
Anway, consider your crossover setup too. It's better to have even-order filter. They cause only a phase shift of 180° which is easy to manage by reversing the polarity of the speaker or (if available) use the radio or amp. If you have uneven-order filter, like 6dB and 12dB you might need a continuously adjustable phase shift.


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## MrLister (Feb 17, 2006)

freemind said:


> What kind of deck are you using?
> 
> I use a Pioneer 860mp and it helps to do the sub alignment.
> 
> But the deck has the toys(but not all of them).


Alpine F#1 w/ PXI-H990. It does have auto TA but I never really trust those, I always prefer to do it by ear as much as I can and I usually find better results that way.



pjhabit said:


> Would T/A help you get away w/ a higher LP point, while still keeping the bass up front?


From what I heard, it can definitely put the bass and staging up front and it makes sense. With the subs being so far away and playing at the same time as the result speaker, it's quite a lag behind so the bass notes are not reaching you at the same time but rather later on.



donkeypunch22 said:


> 1. Measure distance from forehead to all speakers in meters (0.00 accuracy is more than enough).
> 2. Distance of farthest speaker (usually your sub) - distance of speaker to adjust
> 3. Divide by 343
> 4. Multiply by 1000
> ...


Awesome thanks! I have my mid-bass playing down to 60 hz which definitely helped. Another tutorial I found was http://www.diymobileaudio.com/forum...-realized-easy-way-calculate-time-delays.html for those interested


I'll play around with it today and post a "what worked for me" based on all the tips above and other links I found. It will most likely be tape measure first for initial and then playing around with different songs to see which ones I can hear a difference in and I think this will be tougher part but I got some songs in mind.


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## MrLister (Feb 17, 2006)

One other interesting thing to consider is from which point do you measure the subwoofer distance from if the woofer is facing the back of the car?

1) from the cone to driver
2) from the cone to back of trunk, and then from back of trunk to driver

I'm thinking #2 since that's the path that the waves would follow.


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## mvw2 (Oct 2, 2005)

Start with a tape measure. That'll get you close.

Second, you'll want to find useful songs that have a good bass note that incorporates both the mid woofer and sub in the sound. Listen to the song, or a variety of songs even, and pay attention to the bass note. Adjust the TA setting both above and below what you guessed with the tape measure. Try and listen to how the beat syncs between the sub and mids. Also pay attention to dominance. If the mid comes in early, it will have a dominant presence. If the sub comes in early, it tends to become dominant. As they get more correct, neither will overshadow the other. 

When you're set correct, both the presence and articulation of note will be synced between the two.

I'll make a side note that I have found it to be easier to try and sync one mid woofer at a time to the sub. Set balance all the way to the right so you only hear the right woofer. Then adjust the woofer TA till it syncs with the sub. Note that your head and ear position will change as you turn your head, so try not to move around all over the place when doing this. You can do the right woofer and sub and then left woofer and sub or you can do the right woofer and sub and then TA the left woofer with the right.

In the end, you should be very close to what the tape measure said initially. You'll really only be a notch or two off at the most. Be wary of reflections. The car's a reflection rich environment, and you can very easily TA in a reflection rather then the original wave if you're not paying attention. This is why I say you will generally be pretty close or dead on with the tape measure. If you aren't, you are most likely TAing a reflection wave and you may want to start over again.

I'll also note that the group delay of the subwoofer (ported designs) will also play a roll in the TA setting. You have the option to tune partially to counter that group delay. It depends on where you have the sub crossed and how much and where the delay is. You'll notice it a little as you TA where you seem to focus towards the higher beat frequency or the lower frequency range as you adjust. You won't get this with sealed setups since the group delay is so minimal, but it can be noticeable in ported applications where the delay is 15, 20, 30ms or more sometimes.


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## frankmehta (Jan 20, 2009)

dkm201 said:


> Assuming the sub is the furthest speaker from your listening position, you'll want to time delay everything ELSE, not the sub...





MrLister said:


> One other interesting thing to consider is from which point do you measure the subwoofer distance from if the woofer is facing the back of the car?
> 
> 1) from the cone to driver
> 2) from the cone to back of trunk, and then from back of trunk to driver
> ...



then doesn't it mean that the above 2 statements are totally contrasting each other???
one says delay the sub , and the other says DO NOT.
please explain this in detail


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## MrLister (Feb 17, 2006)

frankmehta said:


> then doesn't it mean that the above 2 statements are totally contrasting each other???
> one says delay the sub , and the other says DO NOT.
> please explain this in detail


How so?

I think everybody agrees that the subs should be part of the T/A. (As mentioned you would use the sub as the 0 mark and delay all other speakers). When people refer to measuring the distance from speaker to your ear it's easily done up front since usually the pathwave is clear to your ear however with a sub if it's facing back of the car the distance traveled is longer than if the sub faces the front of the car so it's a valid test to delay the front speakers based on the distance in two different measurements to see which one works best:

Scenario #1: from sub cone to driver
Scenario #2: from sub to back of car + back of car to driver


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## frankmehta (Jan 20, 2009)

wait a moment. so you say the sub must be at zero..
then how do the 2 scenarios matter? anyways we are not delaying the subs.
sorry for asking this, i didnt get it..


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## falkenbd (Aug 16, 2008)

you could always measure impulse response to set time alignment.


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## OSN (Nov 19, 2008)

frankmehta said:


> wait a moment. so you say the sub must be at zero..
> then how do the 2 scenarios matter? anyways we are not delaying the subs.
> sorry for asking this, i didnt get it..


If the sub is your reference, not delayed, the next furthest driver from the listener would be delayed by the difference in path lengths. If your sub is 7 feet from your head, and your right mid-bass is 4 feet from your head, your right mid-bass time delay would be equivalent of 3 feet of time delay, translated to milliseconds. Your left tweeter could be 2 feet away from your head and 5 feet of time delay. That way, the waves from sub travelling 7 feet arrive at the same time as right mid-bass that's 4 feet away and was "held up by 3 feet," and your left tweeter that's 2 feet away and was "help up by 5 feet."


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## frankmehta (Jan 20, 2009)

right. that's beautifully explained. awesome! knocked it right into my head.


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## OSN (Nov 19, 2008)

frankmehta said:


> right. that's beautifully explained. awesome! knocked it right into my head.


At least, that's how I understand it. Hopefully knocking the right thing into your head. :surprised: I do know there will be some tweaking necessary after doing the math and all, when you actually hear how it turns out, but this is the closest approximation I know of.


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## frankmehta (Jan 20, 2009)

yes, but it sounds logical. brings home why TA was there in the first place!


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## Fast1one (Apr 6, 2007)

Andy Wehmeyer said:


> Bass up front depends much more on the response in the transition from bass to midbass and on woofer distortion and rattles than it does on time alignment. Shoot for a smooth transition from 60-160 Hz and between 6 and 9dB more bass than midrange. Then, once the bass sounds more like it comes from up front, adjust the delay for the rest of the front speakers to improve the bass up front illusion. Adjust all of the front speakers by the same increments.
> 
> This is difficult to measure acoustically, because high frequencies are helpful in viewing the initial peak in the response. Also, the group delay in the sub's response, which is a function of the response roll-off is also difficult to measure. That's why setting the sub using the tape measure and making final adjustments by ear is the best and quickest way to do this part.


BIG x 2 here. For years I had been trying to crossover the fronts as low as possible. Crossover the front stage at the lower limits of the response and no lower. Also take into account the 12db/octave roll off of the drivers (depending on the alignment) and the acoustic phase shift at that point. Then crossover the sub to match, playing with slopes and inverting phase.

That gets you pretty damn close. T/A is just icing on the cake.


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## MrLister (Feb 17, 2006)

OldSchoolNewbie said:


> If the sub is your reference, not delayed, the next furthest driver from the listener would be delayed by the difference in path lengths. If your sub is 7 feet from your head, and your right mid-bass is 4 feet from your head, your right mid-bass time delay would be equivalent of 3 feet of time delay, translated to milliseconds. Your left tweeter could be 2 feet away from your head and 5 feet of time delay. That way, the waves from sub travelling 7 feet arrive at the same time as right mid-bass that's 4 feet away and was "held up by 3 feet," and your left tweeter that's 2 feet away and was "help up by 5 feet."


Right, what I was talking about is how do you measure the "7 feet". Is the 7 feet from the cone to driver seat or is it from cone to back of car + back of car to driver seat

So in scenario #1 let's say it's 7 feet
in scenario #2 it would be more than 7 feet


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## falkenbd (Aug 16, 2008)

MrLister said:


> Right, what I was talking about is how do you measure the "7 feet". Is the 7 feet from the cone to driver seat or is it from cone to back of car + back of car to driver seat
> 
> So in scenario #1 let's say it's 7 feet
> in scenario #2 it would be more than 7 feet


that is why measuring the sub distance doesn't work perfectly. measuring along with adjusting by ear or even measuring the impulse response (to get actual time delay) is better


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## gijoe (Mar 25, 2008)

I'd say measure from the cone. Bass is omni directional and the sound from the cone will reach you before the reflected sound, even with the subs firing away from you. You will want to tweak a little here and there because the reflected sound will also come into play, but I think it would be in your best interest to take the measurements from the cone and start from there.


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## donkeypunch22 (Nov 5, 2008)

Andy is the man. Thanks for the info!


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## donkeypunch22 (Nov 5, 2008)

MrLister are you using the F1 H990? If you are, are you using the computer program to tune the system? If not, you should. Much easier than trying through the deck.


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## MrLister (Feb 17, 2006)

donkeypunch22 said:


> MrLister are you using the F1 H990? If you are, are you using the computer program to tune the system? If not, you should. Much easier than trying through the deck.


Yea I got the program and saying it's "much easier than trying through the deck" is a insanely massive understatement


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## donkeypunch22 (Nov 5, 2008)

Agreed. I learned the hard way. I was too lazy or too stupid to grab a pc and hook it up. Thought it would be faster to just use the deck. That was dumb. The program makes things so much easier and faster.

Are you using the parametric EQ or the graphic? I have been using the parametric, and although I am happy with the results, I think it falls short in several critical areas. Not being able to dial in any frequency, not being able to have consecutive bands any closer than "4 steps", and not being able to shelf high or low are the three that bug me the most.


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## foosman (Oct 14, 2007)

When I was learning to tune a system initially, I was told by Scott B. the following and it has proven to work out well for me.

Also, put NO time alignment on the subwoofers. This will help impulse response, and help to bring the bass up front. Use time alignment on all other channels.


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## Oliver (Jun 25, 2007)

MrLister said:


> Any good tips on how to time align a sub woofer?


Try it all the way one way and then all the way the other way....

Eventually , you will hear something you like...leave it there


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## 14642 (May 19, 2008)

foosman said:


> This will help impulse response, ...


Iber sniben fliber giben woope doopee snoopy loopy. Reminds me of a video training i saw once for a retroincabulator.

Here it is:

YouTube - Retroincabulator


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## Oliver (Jun 25, 2007)

Mic10is put TA on his sub when he won at IASCA :surprised:


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## BigRed (Aug 12, 2007)

or this  sorry, had to 

YouTube - JBL do'n it big at CES 2007


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## donkeypunch22 (Nov 5, 2008)

All right, stop picking on Andy, and lets just ask this guy and be done with it:

YouTube - Ask A Ninja Question 16 "How To Kill A Ninja"


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## frankmehta (Jan 20, 2009)

Here's one more question. In a passive setup, how does one practise time alignment? I mean which speaker(the tweeter or the midbass) does one consider when the 'front left' and 'front right' parameters on the head unit need to be punched in?

Also, is time alignment used JUST for bass? Or does it have any other advantages?


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## Mless5 (Aug 21, 2006)

With passives you can only balance left to right.
TA is not for subs only. It is used more for staging and height.


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## frankmehta (Jan 20, 2009)

So then how does the time alignment for the bass come into question in a passive setup, if only the left right staging is taken care of?


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## jsun_g (Jun 12, 2008)

x2 on mvw2's advice below. I can attest to this for my ported sub box in the trunk. First, I aligned the front midbass drivers with the sub turned off, then turned on the sub and put in some music with a distinct kick drum that spans several octaves (for e.g. having high frequency content of the mallet striking the drum). I increased the time delay of the front stage until the entire frequency content of the kick drum seemed to arrive at the same time, which really helped create the illusion of upfront bass. No time delay on the subs.




mvw2 said:


> Start with a tape measure. That'll get you close.
> 
> Second, you'll want to find useful songs that have a good bass note that incorporates both the mid woofer and sub in the sound. Listen to the song, or a variety of songs even, and pay attention to the bass note. Adjust the TA setting both above and below what you guessed with the tape measure. Try and listen to how the beat syncs between the sub and mids. Also pay attention to dominance. If the mid comes in early, it will have a dominant presence. If the sub comes in early, it tends to become dominant. As they get more correct, neither will overshadow the other.
> 
> ...


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## jbholsters (Jun 17, 2009)

You shouldn't take your baseline measurements from the speaker cones, but from the voice coil plane. Depending on the speakers this could the the diffence of 3-9 inches.


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