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General Car Audio
Precision time alignment using only noise tracks and your ears
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<blockquote data-quote="Greg200SE-R" data-source="post: 7168674" data-attributes="member: 560729"><p><span style="color: Blue"><strong>Tuning</strong></span></p><p></p><p><strong><span style="color: Blue">1) Align sub and passenger side midbass</span></strong></p><p></p><p>Mute all drivers except for these two. The sub will remain at 0 ms, and delay will be adjusted for the midbass. Begin your noise track (preferably pink noise since we're in the low frequency range) and turn up the volume loud enough to closely examine the signal.</p><p></p><p>Start increasing delay for the midbass, and listen to for changes in the sound. In the sub/midbass crossover region there are frequencies where both drivers are playing, and this overlap is out of phase. These harmonics appear as an incoherent rumble within the pink noise. As time delay reaches the correct range, the rumble will take on the pattern of the Doppler Effect.</p><p></p><p>More specifically, as delay is increased, listen for one of two possible occurrences:</p><p></p><p>a) The rumble shows itself around 60 Hz, rises in pitch to around 250 Hz, disappears, and then falls again from 250 Hz – 60 Hz.</p><p></p><p>b) The rumble shows itself around 250 Hz, falls in pitch to around 60 Hz, disappears, and then rises again from 60 – 250 Hz.</p><p></p><p>This event may occur anywhere between 0.75 and 3.00 ms. Try holding down the time delay key to scan quickly up and down between zero to 3.50 ms, this makes it easier to hear the pattern. When you think you hear it, note the approximate delay setting. Slowly scan up and down around that area and do your best to locate the center of the peak or trough, where the harmonics/rumbles disappear. This doesn’t have to be absolutely perfect yet, just get it close (the next step will fine tune the delay). Restore your normal XO settings and move on to step 1a.</p><p></p><p>(Note) If you’re having trouble hearing the Doppler Effect, go ahead and force both drivers to overlap and play the same frequencies – set both to play up to 300 Hz. Leave a 40 Hz high pass filter on the midbass to filter out low bass though. Go back and listen for the Doppler Effect again. When you’re finished with all of step 1, restore your normal XO settings and move on to step 1a.</p><p></p><p><strong><span style="color: blue">1a) Verify your delay setting </span></strong></p><p></p><p>The following is an example of how to zero in on, and verify the precise delay setting. Just as an example, say your best guess from step 1 is 2.00 ms delay.</p><p></p><ul> <li data-xf-list-type="ul">Hit the delay “up” button and count how many presses it takes to hear a discernible change in phase (could be up to 30+, depending on time increments).<br /> </li> <li data-xf-list-type="ul">Say it takes 20 button presses to notice a change in phase (the rumble sound will return). Note the number 20.<br /> <br /> </li> <li data-xf-list-type="ul">Return to where you started – 2.00 ms.<br /> </li> <li data-xf-list-type="ul">Now, hit the down button the same number of times (20) – you should hear the very same rumble/phase change appear.<br /> </li> <li data-xf-list-type="ul">If it takes more or less than 20 presses, adjust your 2.00 ms delay up or down accordingly.<br /> </li> <li data-xf-list-type="ul">Repeat these steps until correct.<br /> </li> </ul><p></p><p></p><p>You’ve just eliminated the most apparent phase incoherencies between the 2 drivers, and they are now correctly aligned to your ears. And that’s how the method works. All other drivers repeat the same basic procedures. Each alignment depends on the one before it, so precision and patience in the first steps of the process is paramount.</p><p></p><p>(Note) This verification procedure will be repeated for all drivers.</p><p></p><p><span style="color: blue"><strong>2 and 2a) Alignment and verification: sub and driver side midbass</strong></span></p><p></p><p>Mute all other drivers and adjusting delay for the driver side midbass. Note that because this midbass is closer to your ears than the passenger side, the time delay will end up slightly greater than the passenger midbass. The Doppler Effect will seem to appear and disappear more quickly as well.</p><p></p><p>Once you think you have the correct delay, verify using the same method as in (1a); this time, it should take fewer presses of the up/down button to hear a change in phase.</p><p></p><p><strong><span style="color: blue">3) Verify alignment: both midbasses</span></strong></p><p></p><p>Save your TA settings. You’ve just individually aligned your midbasses using the sub as their reference. Now it’s time to listen to both midbasses together. Mute all other drivers and return the XOs for the midbasses to their normal frequencies.</p><p></p><p>Play the pink noise and listen for the width and center of the presented soundstage. It should be quickly apparent that the image is solidly centered. If soundstage is not cohesive (almost like drivers are wired out-of-phase), or pulling to one side, then the best thing to do is go back to steps 1 and 2, and refine/re-verify your time delay settings. Making any arbitrary time adjustments during this verification step will do more harm than good.</p><p></p><p>An incoherent or off-centered soundstage can be caused by zeroing in on the wrong Doppler Effect (the second one that appears as opposed to the first one). As you get better at recognizing the Doppler Effect during the first 2 steps, the midbasses tend to automatically end up correctly aligned, and no changes need to be made in this step.</p><p></p><p>Don’t continue until you’re confident of your midbass time delay settings.</p><p></p><p><strong><span style="color: blue">4 and 4a) Alignment and verification: passenger side midbass and tweeter</span></strong></p><p></p><p>We’ll continue the process with the passenger mid/tweeter combo. Since this step deals with the midrange frequencies, playing back white noise instead of pink may be better (but not required). Use your normal XO settings, mute all other drivers and play the noise track.</p><p></p><p>The midbass will now be the reference; its predetermined delay setting will not change. Adjust tweeter delay until the Doppler Effect is heard. It will be more pronounced and easy to hear this time because the XO region is now in the midrange, and because the mid and tweeter radiating surfaces are physically quicker. The tweeter’s time delay should end up relatively close to that of the mid. If you have problems hearing the effect, use the XO filters to cut the high-end response of the tweeter, and cut the low frequencies of the midbass.</p><p></p><p>Verify using same procedure as above. It will take fewer button presses to hear a phase change.</p><p></p><p><strong><span style="color: blue">5 and 5a) Alignment and verification: driver side midbass and tweeter</span></strong></p><p></p><p>You know what to do. This one is a bit tricky because of the angle and proximity of the 2 drivers relative to your head. The Doppler Effect will come and go quickly. During verification, it should take very few presses of the up/down buttons to hear a change in phase.</p><p></p><p><strong><span style="color: blue">6) Verify alignment: both tweeters</span></strong></p><p></p><p>Save, or write down your TA settings. Restore both tweeters’ high-pass filters to their normal frequency. Listen to noise on both tweeters together and verify your settings from the last few steps. Again, listen for the width and center of the presented soundstage. Same deal, if it’s pulling to one side or incoherent, go back to steps 4 and 5 and refine/re-verify your time delay settings.</p><p></p><p><strong><span style="color: blue">7) Verify alignment: front stage</span></strong></p><p></p><p>Normal up the XOs for your entire front stage. Leave the sub off. Still playing the noise track, double-check for coherency and general staging. This is just a final verification of your settings, and if your verifications have been good up till now, this should not require any adjustments.</p><p></p><p><strong><span style="color: blue">8) Normal up all settings and evaluate</span></strong></p><p></p><p>This is the moment of truth. Normal up all of your XO settings, and save the configuration to memory. Play some music through your system and evaluate.</p><p></p><p>If you’ve never set TA by ear, and you’ve followed the steps with confidence in your determinations, there should be a very noticeable difference. Each time you go through the process, you’ll be better at recognizing the Doppler Effect and further refine your sound.</p><p></p><p><strong><span style="color: Blue">Improvements</span></strong></p><p></p><p>With correct application, this method achieves immediate improvements in imaging, staging, impact, and transparency. Bass should become thinner, but in a good way - lean, with great impact. The sub-bass shouldn’t come from the back of the car, or even up front – it should be completely unlocalizable. Midbass should be solidly up front along with the rest of the center image.</p><p></p><p>That said, TA doesn’t magically transform your system into a rolling 5-digit audiophile’s dream. It just reduces the tendency for your speakers to fight against each other. Hearing correct TA for the first time can be downright shocking - but this is simply the moment we realize how much the speakers fight against each other within the confines of an automobile.</p><p></p><p>And, of course, this method is no replacement for a carefully installed system with well-placed drivers. But, it will definitely help a modest system with drop-in speakers bridge that gap somewhat.</p><p></p><p>Thanks for reading.</p></blockquote><p></p>
[QUOTE="Greg200SE-R, post: 7168674, member: 560729"] [COLOR=Blue][B]Tuning[/B][/COLOR] [B][COLOR=Blue]1) Align sub and passenger side midbass[/COLOR][/B] Mute all drivers except for these two. The sub will remain at 0 ms, and delay will be adjusted for the midbass. Begin your noise track (preferably pink noise since we're in the low frequency range) and turn up the volume loud enough to closely examine the signal. Start increasing delay for the midbass, and listen to for changes in the sound. In the sub/midbass crossover region there are frequencies where both drivers are playing, and this overlap is out of phase. These harmonics appear as an incoherent rumble within the pink noise. As time delay reaches the correct range, the rumble will take on the pattern of the Doppler Effect. More specifically, as delay is increased, listen for one of two possible occurrences: a) The rumble shows itself around 60 Hz, rises in pitch to around 250 Hz, disappears, and then falls again from 250 Hz – 60 Hz. b) The rumble shows itself around 250 Hz, falls in pitch to around 60 Hz, disappears, and then rises again from 60 – 250 Hz. This event may occur anywhere between 0.75 and 3.00 ms. Try holding down the time delay key to scan quickly up and down between zero to 3.50 ms, this makes it easier to hear the pattern. When you think you hear it, note the approximate delay setting. Slowly scan up and down around that area and do your best to locate the center of the peak or trough, where the harmonics/rumbles disappear. This doesn’t have to be absolutely perfect yet, just get it close (the next step will fine tune the delay). Restore your normal XO settings and move on to step 1a. (Note) If you’re having trouble hearing the Doppler Effect, go ahead and force both drivers to overlap and play the same frequencies – set both to play up to 300 Hz. Leave a 40 Hz high pass filter on the midbass to filter out low bass though. Go back and listen for the Doppler Effect again. When you’re finished with all of step 1, restore your normal XO settings and move on to step 1a. [B][COLOR=blue]1a) Verify your delay setting [/COLOR][/B] The following is an example of how to zero in on, and verify the precise delay setting. Just as an example, say your best guess from step 1 is 2.00 ms delay. [LIST] [*]Hit the delay “up” button and count how many presses it takes to hear a discernible change in phase (could be up to 30+, depending on time increments). [*]Say it takes 20 button presses to notice a change in phase (the rumble sound will return). Note the number 20. [*]Return to where you started – 2.00 ms. [*]Now, hit the down button the same number of times (20) – you should hear the very same rumble/phase change appear. [*]If it takes more or less than 20 presses, adjust your 2.00 ms delay up or down accordingly. [*]Repeat these steps until correct. [/LIST] You’ve just eliminated the most apparent phase incoherencies between the 2 drivers, and they are now correctly aligned to your ears. And that’s how the method works. All other drivers repeat the same basic procedures. Each alignment depends on the one before it, so precision and patience in the first steps of the process is paramount. (Note) This verification procedure will be repeated for all drivers. [COLOR=blue][B]2 and 2a) Alignment and verification: sub and driver side midbass[/B][/COLOR] Mute all other drivers and adjusting delay for the driver side midbass. Note that because this midbass is closer to your ears than the passenger side, the time delay will end up slightly greater than the passenger midbass. The Doppler Effect will seem to appear and disappear more quickly as well. Once you think you have the correct delay, verify using the same method as in (1a); this time, it should take fewer presses of the up/down button to hear a change in phase. [B][COLOR=blue]3) Verify alignment: both midbasses[/COLOR][/B] Save your TA settings. You’ve just individually aligned your midbasses using the sub as their reference. Now it’s time to listen to both midbasses together. Mute all other drivers and return the XOs for the midbasses to their normal frequencies. Play the pink noise and listen for the width and center of the presented soundstage. It should be quickly apparent that the image is solidly centered. If soundstage is not cohesive (almost like drivers are wired out-of-phase), or pulling to one side, then the best thing to do is go back to steps 1 and 2, and refine/re-verify your time delay settings. Making any arbitrary time adjustments during this verification step will do more harm than good. An incoherent or off-centered soundstage can be caused by zeroing in on the wrong Doppler Effect (the second one that appears as opposed to the first one). As you get better at recognizing the Doppler Effect during the first 2 steps, the midbasses tend to automatically end up correctly aligned, and no changes need to be made in this step. Don’t continue until you’re confident of your midbass time delay settings. [B][COLOR=blue]4 and 4a) Alignment and verification: passenger side midbass and tweeter[/COLOR][/B] We’ll continue the process with the passenger mid/tweeter combo. Since this step deals with the midrange frequencies, playing back white noise instead of pink may be better (but not required). Use your normal XO settings, mute all other drivers and play the noise track. The midbass will now be the reference; its predetermined delay setting will not change. Adjust tweeter delay until the Doppler Effect is heard. It will be more pronounced and easy to hear this time because the XO region is now in the midrange, and because the mid and tweeter radiating surfaces are physically quicker. The tweeter’s time delay should end up relatively close to that of the mid. If you have problems hearing the effect, use the XO filters to cut the high-end response of the tweeter, and cut the low frequencies of the midbass. Verify using same procedure as above. It will take fewer button presses to hear a phase change. [B][COLOR=blue]5 and 5a) Alignment and verification: driver side midbass and tweeter[/COLOR][/B] You know what to do. This one is a bit tricky because of the angle and proximity of the 2 drivers relative to your head. The Doppler Effect will come and go quickly. During verification, it should take very few presses of the up/down buttons to hear a change in phase. [B][COLOR=blue]6) Verify alignment: both tweeters[/COLOR][/B] Save, or write down your TA settings. Restore both tweeters’ high-pass filters to their normal frequency. Listen to noise on both tweeters together and verify your settings from the last few steps. Again, listen for the width and center of the presented soundstage. Same deal, if it’s pulling to one side or incoherent, go back to steps 4 and 5 and refine/re-verify your time delay settings. [B][COLOR=blue]7) Verify alignment: front stage[/COLOR][/B] Normal up the XOs for your entire front stage. Leave the sub off. Still playing the noise track, double-check for coherency and general staging. This is just a final verification of your settings, and if your verifications have been good up till now, this should not require any adjustments. [B][COLOR=blue]8) Normal up all settings and evaluate[/COLOR][/B] This is the moment of truth. Normal up all of your XO settings, and save the configuration to memory. Play some music through your system and evaluate. If you’ve never set TA by ear, and you’ve followed the steps with confidence in your determinations, there should be a very noticeable difference. Each time you go through the process, you’ll be better at recognizing the Doppler Effect and further refine your sound. [B][COLOR=Blue]Improvements[/COLOR][/B] With correct application, this method achieves immediate improvements in imaging, staging, impact, and transparency. Bass should become thinner, but in a good way - lean, with great impact. The sub-bass shouldn’t come from the back of the car, or even up front – it should be completely unlocalizable. Midbass should be solidly up front along with the rest of the center image. That said, TA doesn’t magically transform your system into a rolling 5-digit audiophile’s dream. It just reduces the tendency for your speakers to fight against each other. Hearing correct TA for the first time can be downright shocking - but this is simply the moment we realize how much the speakers fight against each other within the confines of an automobile. And, of course, this method is no replacement for a carefully installed system with well-placed drivers. But, it will definitely help a modest system with drop-in speakers bridge that gap somewhat. Thanks for reading. [/QUOTE]
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