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<blockquote data-quote="keep_hope_alive" data-source="post: 7506627" data-attributes="member: 576029">don&#039;t forget that you localize sound based in time arrival (ITD) for frequencies below ~3kHz and you localize sound based on intensity (IID) above ~3kHz.Crossover point and slope should be taken into account here.&nbsp; A 3kHz 12dB/oct slope does not get you above the IID point.&nbsp; a 4.5kHz 12dB/oct slope is a better point.&nbsp; The reason should be obvious; the speaker will be audible below the crossover point.&nbsp; When a source is 10dB down relative to other sources, it no longer adds to the cumulative sound pressure level.&nbsp; In other words: if you have two sources producing the same frequency and one is 10dB lower than the other, you only measure one source.This is why people will say that T/A on tweeters isn&#039;t necessary - just proper aiming.&nbsp; What they should clarify is that the statement is only true for crossover points/slopes above a certain frequency.&nbsp; most component sets use a crossover point below 4kHz, so when using passives, you are best to just T/A the whole set - locate your tweeters at a distance from the nearest headrest that is equal to the door woofer, and aim them off-axis relative to the nearest seating position.&nbsp; naturally, this is a general statement and each vehicle should be tested.lastly, T/A is not a requirement for a good soundstage. it is a bandaid for poor placement/installation.&nbsp; sadly, our cars are poor environments for speaker placement.&nbsp; we do our best with placement/install, then use tools are our disposal to fix what we can.<img src="http://i38.photobucket.com/albums/e128/phat_funky_beats/Sound%20Domain/HRTFexplained.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></blockquote>

[QUOTE="keep_hope_alive, post: 7506627, member: 576029"] don't forget that you localize sound based in time arrival (ITD) for frequencies below ~3kHz and you localize sound based on intensity (IID) above ~3kHz. Crossover point and slope should be taken into account here. A 3kHz 12dB/oct slope does not get you above the IID point. a 4.5kHz 12dB/oct slope is a better point. The reason should be obvious; the speaker will be audible below the crossover point. When a source is 10dB down relative to other sources, it no longer adds to the cumulative sound pressure level. In other words: if you have two sources producing the same frequency and one is 10dB lower than the other, you only measure one source. This is why people will say that T/A on tweeters isn't necessary - just proper aiming. What they should clarify is that the statement is only true for crossover points/slopes above a certain frequency. most component sets use a crossover point below 4kHz, so when using passives, you are best to just T/A the whole set - locate your tweeters at a distance from the nearest headrest that is equal to the door woofer, and aim them off-axis relative to the nearest seating position. naturally, this is a general statement and each vehicle should be tested. lastly, T/A is not a requirement for a good soundstage. it is a bandaid for poor placement/installation. sadly, our cars are poor environments for speaker placement. we do our best with placement/install, then use tools are our disposal to fix what we can. [IMG]http://i38.photobucket.com/albums/e128/phat_funky_beats/Sound%20Domain/HRTFexplained.jpg[/IMG] [/QUOTE]

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