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<blockquote data-quote="keep_hope_alive" data-source="post: 7464453" data-attributes="member: 576029">I thought more about the comment that PLD alone can result in poor T/A results.&nbsp; and I think I know where bad experiences with this come from.first and foremost - if you don&#039;t image when you take IID, ITD, HRTF, and PLD into mathematical consideration when adjusting speaker location, aiming, crossover points, and time alignment - then you have phase interference.&nbsp; phase interference is a HUGE problem for people trying to tune a sound stage in cars for a number of reasons.1.&nbsp; it is understood by few people in car audio.&nbsp; most people don&#039;t even consider it or know it exists.2.&nbsp; it is dominated by installation methods.&nbsp; install is the weakest link in most systems.3.&nbsp; if phase (both electrical and acoustic) is not considered in every facet of the install, problems will crop up.the car is a tricky environment due to glass at ear level.&nbsp; we get many specular reflections that throw off the information we are getting.&nbsp; for example, when sound plays from a right speaker, our right ear hears the direct sound then the left ear hears a reflected sound (of almost equal level and bandwidth) a short time later.&nbsp; if we can get the left channel to arrive before the reflected right channel, we have a better chance of properly localizing sound.&nbsp; however, the reflected right channel is on axis and the direct left channel is commonly off axis.&nbsp; to correct for this, we adjust T/A but in doing so we create other issues.if the initial time delay gap (ITDG) is too short, we perceive it as the same sound.&nbsp; much research has been done in the subject of ITDG (a lot by Berenek) and it&#039;s effect on localization - mostly in concert halls but the same concepts apply to car audio.&nbsp; psychoacoustic theory applies regardless of application.another reason is that in car audio, we are trying to put the sound stage somewhere that it is unlikely to be using T/A based on PLD alone.&nbsp; while it won&#039;t sound poor, the sound stage won&#039;t be where your typical competition judge wants it to be.&nbsp; but really, that only matters for a tiny percent of the population - and they aren&#039;t asking general questions in car audio forums.&nbsp; when we&#039;re talking about the above average installation, the majority of people don&#039;t care about a sound stage that is impeccable.&nbsp;&nbsp; they want something that sounds &quot;good&quot;, and &quot;good&quot; can be had with some simple installation methods and tuning techniques.in the end, acoustics is like *** - everyone thinks they are an expert.</blockquote>

[QUOTE="keep_hope_alive, post: 7464453, member: 576029"] I thought more about the comment that PLD alone can result in poor T/A results. and I think I know where bad experiences with this come from. first and foremost - if you don't image when you take IID, ITD, HRTF, and PLD into mathematical consideration when adjusting speaker location, aiming, crossover points, and time alignment - then you have phase interference. phase interference is a HUGE problem for people trying to tune a sound stage in cars for a number of reasons. 1. it is understood by few people in car audio. most people don't even consider it or know it exists. 2. it is dominated by installation methods. install is the weakest link in most systems. 3. if phase (both electrical and acoustic) is not considered in every facet of the install, problems will crop up. the car is a tricky environment due to glass at ear level. we get many specular reflections that throw off the information we are getting. for example, when sound plays from a right speaker, our right ear hears the direct sound then the left ear hears a reflected sound (of almost equal level and bandwidth) a short time later. if we can get the left channel to arrive before the reflected right channel, we have a better chance of properly localizing sound. however, the reflected right channel is on axis and the direct left channel is commonly off axis. to correct for this, we adjust T/A but in doing so we create other issues. if the initial time delay gap (ITDG) is too short, we perceive it as the same sound. much research has been done in the subject of ITDG (a lot by Berenek) and it's effect on localization - mostly in concert halls but the same concepts apply to car audio. psychoacoustic theory applies regardless of application. another reason is that in car audio, we are trying to put the sound stage somewhere that it is unlikely to be using T/A based on PLD alone. while it won't sound poor, the sound stage won't be where your typical competition judge wants it to be. but really, that only matters for a tiny percent of the population - and they aren't asking general questions in car audio forums. when we're talking about the above average installation, the majority of people don't care about a sound stage that is impeccable. they want something that sounds "good", and "good" can be had with some simple installation methods and tuning techniques. in the end, acoustics is like *** - everyone thinks they are an expert. [/QUOTE]

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