Quote:
Originally Posted by avanti1960 View Post
Update 4/22/2012.
After hours of experimenting with manual time alignment settings, I stumbled on a very simple way to dial in the settings after an autotune. First off, let me please say they I have never heard a car stereo sound like this before. It is a whole other world of sound quality once the stage is truly time aligned.
I had an Alpine CDA 117 before and could never get it to sound right so I never really understood how big of a benefit it can be for sound quality.
Basically I ran the "best" autotune sweep for mic position that I had achieved to date- although a per-the-manual autotune as a starting point would probably work.
Then I needed a decent source to play in order to fine tune the settings.
The articles I have read that suggest other methods (manual time alignment using noise and listening for the doppler effect, time alignment by finding the worst out of phase sound) somehow did not seem very easy to work with. All I wanted was for the image to be "centered" equally as to provide a nice stage. I know the autotune on the DEX really struggles with this, the image tends to wander all over the place, probably due to the amount of cabin reflections the various drivers and frequencies show.
So i thought, how do I center the image using time alignment? I really need to do this using music with my own ears because in the end that is what I am hearing when the system is in use.
I thought about using a mono source, since there would be no stereo or studio effects that alter the image position and that I would strictly be adjusting image to center it among the drivers.
AM radio was an option that I quickly dropped because it is not dynamic enough and has a limited frequency range.
I looked at my demo CD "My Disk" by Sheffield labs. It has a mono track of really dynamic, full range well recorded music. Unfortunately it is very short, so I put it on repeat track.
I then decided right or wrong that the "distant" speakers were somewhat OK per the autotune and decided to only adjust the left tweeter, the left midbass and the left rear passive. I wanted to see how this would work. The distances shown on the autoTA seemed reasonable for those farther away drivers on the right side and the sub.
I isolated the tweeters (mounted in stock position just below sail panels).
I changed the crossover to 3K so that they would play a decent range of frequencies.
First off, all levels were set equally and I had the balance position set to the right by (2) on the scale.
I played the mono track and began adjusting the distance settings of the left tweeter. I wanted to focus the tweeter sound to the center of my windshield. I listened carefully as I heard the image go from left to right and back again just by adjusting the left tweeter TA distance.
When I was happy with the center of the tweeter image, I then turned them down and isolated the front mid-bass drivers, located on the bottom front door panels.
Whoaa- this image was really biased to the left. No wonder the stage was crappy.
I again set the mono track on repeat and adjusted the distances on the left mid driver only.
It was a lot easier to center than the tweeters. I quickly had the midbass drivers centered with time alignment.
Then did the same to the rear door drivers. These were already close to center so it did not take too much to adjust he left rear driver to center the rear image.

I then adjusted all crossover points to normal as well as the levels.

Then I played one of the demo tracks (stereo) on the Sheffield labs disk-

I actually shouted out loud in my car in my garage when I heard it for the first time. Un believably amazing. Seriously, I have never heard this before ever- anywhere. I played the FM and a few CDs. Completely blown away. A whole new league and dimension to the sound. The highs are so much brighter but somehow smoother and more natural. The vocals are dead center in my windshield. The left / right stereo effects for instruments or other studio tricks pop out with precision- a keyboard pops out left of center- stays right where it should- and sounds clear and amazing. A guitar springs up to the right of center. Cymbals crash on the far right.
Simply astounding- and very easy to get to using a high quality dynamic full range mono music track.
DEX owners- be prepared to be blown away if you have such an opportunity.
Congrats, I know the feeling. But would you believe there may be even more to be had? The method using the noise (listening for doppler effect) not only centers your image but it also makes sure the tweeter is in phase with the mid, the mid in phase with the sub etc. So while you have the mids adjusted L and R try the noise method on the tweeter/mid first on the left side and then adjust the right side, (don't change the mid TA, just adjust the tweeter).
You will be in audio heaven soon