40 replies to this topic

[wazzab4]

I have done some time alinegment today and well it did not work out.
1st i did it for the driver seat only and it sounded good from drivers seat but bad from the passanger.
So 2nd i did my setting to the middle of the car between the drivers seat and the passanger seat and it sounded bad from both.
Then 3rd i tryed adding the two drivers side T/A numbers together, Then divide it by two to try and get a good T/A from both seats. But that did not work.

So my question how do you T/A for both seats.
Where do you measure too, How do you do it.

Wazza

Edited by Pulse-R, 21 April 2009 - 10:58 PM.

[BMWTurbo]

In short you can't TA 'perfectly' for both seats. You can either set a compromise for both seats, or set near perfect for one side but obviously detract from the other side.

What you can do is set the TA up so that on a single point for bewteen the driver and passenger seat you have the best TA response for both seats at the same time. What this means is that you are setting the tweeters/midrange/midbass/sub drivers to all reach the centre point between the passenger and drivers head at the same time.

Well in theory anyways. You will not be able to have any Left to Right bias when setting for both seats, you should only set each driver 'pair' relatively to each other driver' pair. If you have any left or right bias you are robbing Peter to feed Paul, so it's gain one side, reduce from another for want of better way to describe it.

[~Spyne~]

yeah, its impossible to set t/a for BOTH seats at the same time. by setting t/a, you are (in effect) decreasing path length differences for one seat, but by doing that, you are increasing the path length difference for the opposite seat.

the best you can do, is either aim for smack in the middle and have a compromise for both seats or set perfectly for one side only (one of the top 3 expert competitors in vic does this) and know that you will score baddly for imaging from the opposite seat.
of course, if you can use speaker placement in the first place, to get as close as possible to equal path length differences for all drivers, then you eliminate the need for t/a and WILL be able to image very well from both seats

[Pulse-R]

use your ears

if it sounds ok, but out of phase, then change the phase.

all the nay-sayers above haven't done two-seat TA successfully.
I have. not perfect, but pretty darn good.

[BMWTurbo]

Pulse-R, on Apr 19 2009, 06:13 PM, said:

use your ears

if it sounds ok, but out of phase, then change the phase.

all the nay-sayers above haven't done two-seat TA successfully.
I have. not perfect, but pretty darn good.

Can you elaborate on what you are actually referring to here Pulse-R, perhaps give an indication of your settings.

I'm intersted in how delaying one side more then then other could improve imaging for the side that has the PLD's effectively increased through this process?

[Pulse-R]

I have T/A using my ears.
The crossover frequencies are quite critical.

left/right settings are within about 0.2ms of each other, but the drivers are set to approximately the distances.

once you get the TA as close as possible, EQ helps to 'tighten up' the image and/or move it a little left/right as necessary.
it's impotant to have EQ separate for each driver, as little changes around the crossover frequency may affect the imaging from more than one speaker - i.e. 2kHz affects mid and high, so make sure you're adjusting the right thing.

ears are the best tools to use. and good music with strong centre images at various frequencies.
the warble tones on My Disc work ok for trimming EQ.

[Juls]

The only thing can really TA to both seats, is attempt to equal up the sub with the midbass, IF the sub is the furtherest away speaker. (which for the majority, this is the case) or equal the midrange to the tweet, technically with both seats, both sides need the same settings, so it can only be used to equal up one singular or pair of speakers with another singular or pair.

To get good sound from both seats, particularily Image and stage width and depth, then in some ways it comes back to buying the right car.. (or the right room as such) since the majority of cars it's near on impossible to get all speakers equal distances apart, for both the driver AND the passenger.

in pro comp where the image and sound must sound perfect from both seats, vehicles with deep dashes, kicks or doors, will always tend to do much better, since the speakers can be placed further away, and therefore more even to both the driver and passenger.

in a car where it's not possible to get equal distances, i'm sure there is plenty of tricks you can do to try and make it sound right in both seats, but i think near perfection (or at least high scoring SQ setup) is particularily difficult, if not almost impossible.

In this case, I'd just forget the stupid passenger, and focus on the driver, and just stick to Pro Street.. and forget the expert SQ classes. (or forget competition altogether)

IMO, SQ Rules should be dumped which contain scoring from both seats in favor of driver only, this would allow for more near or totally perfect systems to be achieved, instead of lots and lots of mediocre ones. It also allows for modern technology and system design thinking, instead of applying very old school ideas which never intended the use of modern technology.

We do build these systems for ourselves don't we?? not the passenger!

Hell for 99.99% of people who sit in the passenger side if you don't tell them it's better where you sit, they will never know! Do you really need to impress that person with your car stereo?

When it comes to building a system to compete in Expert SQ, you really have to ask yourself, "who are you spending the money on" is it you, or is it to get the pat on the back from some random person who comes up with a opinion about your much loved system. If your spending thousands (and sometimes tens of thousands) to please someone else, then maybe your prioritys are mixed up, and it's not really about the sound.

My stereo is for me, NO ONE ELSE, I'm the only person that needs to be happy with it since i listen to it 99.5% of the time on my own.

Juls

Edited by Juls, 20 April 2009 - 01:29 PM.

[Gonadman2]

... and it sounds pretty damn good on the drivers side Juls!

[muzzy66]

wazzab4, on Apr 19 2009, 07:06 AM, said:

I have done some time alinegment today and well it did not work out.
1st i did it for the driver seat only and it sounded good from drivers seat but bad from the passanger.
So 2nd i did my setting to the middle of the car between the drivers seat and the passanger seat and it sounded bad from both.
Then 3rd i tryed adding the two drivers side T/A numbers together, Then divide it by two to try and get a good T/A from both seats. But that did not work.

So my question how do you T/A for both seats.
Where do you measure too, How do you do it.

Wazza

I measure the distance between the left mid and left tweeter, then the distance between the right mid and right tweeter.

If the install is symmetrical, then those two distances should be the same. If so I apply the same amount of time alignment on the left side as I do on the right side, and then fine tune by ear.

If there is a slight difference, then I average the two sides and apply the average to both sides, then fine tune by ear.

I always apply speaker-specific time alignment, rather then driver focussed time alignment. What I mean by this, is I aim to get the left tweeter/mid/midbass in time with each other, then the right tweeter/mid/midbass in time with each other. I never attempt to get the left and right side in time with the driver or passenger, because if you do this then the timing will be excellent on one side of the car, but completely out of wack on the other side of the car. I just accept the fact that you'll never get a centre image from both seats.

As long as the drivers themselves are in time (tweet in time with mid, which is in turn in time with midbass) then it should sound good.

[syd-monster]

Simon (pulse-R) hit a specific point. X-over points

T/A isn't going to solve it.

T/A is an after-tool. You shouldn't rely on it.

What should happen is during installation you shoul work on speaker placement, axis angles, phase & cross-over points with NO T/A. Get it all a close as possible, if not perfect.
Now this may take a LONG time, but its the price for hi-end competiton SQ in an already compramised environment (cars). Now not all of us have this sort of time, hence short-cut tools like T/A, active x-overs, DSP's & PEQ's were all introduced as tools to help us tune faster. A not so long ago, we didn't have T/A and trust me when I say, cars imaged.
A better tool is to use an RTA & Pink noise disk, get your levels right after doing all the above. Then go for T/A at the end.

[syd-monster]

Wazza,

Some Tuning links that may help you get your head around it all.
This isn't the be all end all, but a good read non the less.

http://www.diymobileaudio.com/forum/diyma-...ips-cmusic.html

http://www.diymobileaudio.com/forum/diyma-...ctive-user.html

http://www.diymobileaudio.com/forum/diyma-...esy-cmusic.html


Converter for T/A and other things
http://www.sengpiela...culations03.htm

Frequencies.

http://marchandelec.com/sweeps.html

http://www.dak.com/r...frequencies.cfm

Edited by syd-monster, 20 April 2009 - 04:31 PM.

[SCorpion]

wazzab4, on Apr 19 2009, 05:06 PM, said:

So 2nd i did my setting to the middle of the car between the drivers seat and the passanger seat and it sounded bad from both.

what?

you sat in the middle of the car and then did your T/A?

are your drivers not equal distance from the middle of the car? because if they are, then there should be no T/A adjustment between the drivers if you are sitting in the middle of the car.

i've never understood how T/A works.

people say that it is making the path lengths the same. which is all well and good, but the angle between the listener and the driver is still going to be different.

Therefore, equalizing path lengths is only going to go some way to getting an image centered.

I just did a quick calc then, if the difference in path lengths is half, then to get a centre image you need to double the difference in path length.

but this doesn't correspond in car. so the only conclusion i can draw is that those T/A adjustment tables you get in the manuals are completely useless, as are any calculators UNLESS you take into account the difference in angle as well.

i shall upload an image once i can use the scanner

[Pulse-R]

path length and distance from you to the driver aren't always the same thing.

acoustic phase and distance are hard to measure, but relatively easy to hear. As syd-monster said, it takes hours of testing and listening and tweaking to get it just so. computers can't hear, so they won't be much help.

[SCorpion]

Pulse-R, on Apr 20 2009, 05:18 PM, said:

path length and distance from you to the driver aren't always the same thing.

acoustic phase and distance are hard to measure, but relatively easy to hear. As syd-monster said, it takes hours of testing and listening and tweaking to get it just so. computers can't hear, so they won't be much help.

no, i simplified the T/A idea and put it into an ideal scenario.

people go on about how T/A is about making the "path length" the same to centre an image. but the angles between listener and drivers vary from left side to right side. so in my theoretical case, you need to DOUBLE the adjustment in T/A to get a centre image.

the doubling of the adjustment puts the adjustment WELL into the late reflection and even nearly echo region. i am talking 20ms+ sometimes. thats not acoustic phase issues at all.

i shall scan a picture up sometime soon to show what i mean.

[Pulse-R]

no processor around (except a few pro audio ones) allow TA greater then 20ms.

and having all the speakers aligned the same 20ms defeats the purpose, as you need a reference in the near-field, and align to that reference. i.e. if all sound is delayed by 20ms, then you just hear the same thing, but 20ms later.

if you delay a tweeter by more than 1ms compared to the acoustic disance of the mid, then you can hear the 'echo' and it's terrible.

The point of two-seat listening (and tuning) is to step above the electonics, and use your brain.

There are 2 distinct schools of thought regarding setup of an audio system:

1. Get the install perfect, and everything else takes care of itself.
2. Use electronic wizardry to improve the sound.

Personally, I use a combination of the two - get the install mostly right (but remain practical), and then use the electronics to
improve the result.

This of course relies on having good source, amplification and speakers. If any one of those lets you down, the whole system suffers.