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I read a post in the "High-End" audio forum written by a vendor that suggested ported front speakers are not a good choice to use with a sub-woofer - he was implying that sealed enclosures work better with subwoofers.


Does it really matter when applied to the ordinary consumer grade system or is that just an issue with exotic sound systems.
 

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It really does not matter, in my opinion.
 

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Typically depending on the speaker, you would be crossing over at a frequency well above the area where the port is having the most effect. Therefore it shouldn't be much of a factor.
 

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The intergration of a ported full range speaker to a sub will be dependant on the correct crossover point and slope in relationship to the tuning frequency of the speaker. The Freq response of the sub and it's ability to play at or above the xover point should also be considered as well. Larger drivers 'generally' don't do well higher up the spectrum with cone breakup being the most common artifact to result. For example, if you choose a crossover setting of 80z, the sub will be playing material above 80z, but at a reduced output. The same goes for the speaker below the 80hz xover point. Smaller drivers usually stuggle with LF content due to the small surfae area of the cone and the limited excursion of the drivers suspension. How much reduction or how far up the audibility would be dependant on the 'slope' of the low pass filter used or in the case of the speaker how low or loud dependant on the high pass filter slope used.


Personally i prefer all sealed for smaller driver systems. It prevents the drivers from playing to broad of a spectrum which reduces power handling and introduces distortion. Crossing well above tune in a ported system works good too. From here it's just subjective or opinion based on listening taste.


Basically what you want to achieve is a Subwoofer taking over the low freq playback at a point above where the main speakers begin to roll off thier low frequency playback without having a hump or null in the response at or around the crossover point. The placement of both the mains and subwoofer will also play a part in the overall response. All of this is best accomplished with measuring tools but with carefull listening and experimentation and adjustments, the same results can be realized.
 

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Has anyone ever wondered why THX does not permit ported speakers to be used for the main speakers? All THX rated main speakers are sealed.


If you have a typical smaller speaker that is ported, the problem with the port is change of phase. The phase at the port frequency inverts by 180 degrees. Kind of hard to properly blend a ported speaker with a subwoofer when phase is so screwed up.


The use of "large" main speakers can also cause phase mismatch problems if you use a ported subwoofer!
 

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Quote:
Originally Posted by J_Palmer_Cass /forum/post/15493967


Has anyone ever wondered why THX does not permit ported speakers to be used for the main speakers? All THX rated main speakers are sealed.


If you have a typical smaller speaker that is ported, the problem with the port is change of phase. The phase at the port frequency inverts by 180 degrees. Kind of hard to properly blend a ported speaker with a subwoofer when phase is so screwed up.


The use of "large" main speakers can also cause phase mismatch problems if you use a ported subwoofer!

It looks like THX had a solution for that problem too with the THX-T3.
 

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Quote:
Originally Posted by J_Palmer_Cass /forum/post/15493967


Has anyone ever wondered why THX does not permit ported speakers to be used for the main speakers? All THX rated main speakers are sealed.

Most THX speakers aren't what you would call full range. They are usually rated down to 80hz or so and are designed to be used with a sub or pair of subs. If they were ported, that would put the port tuning in the area of the crossover, so instead they are sealed. Most good typical full range speakers will have decent response down to below 50hz or better. That would get the port tuning well beneath the typical crossover region.
 

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Yep. The ports are not that active when you have the 80Hz crossover and speakers are set to small. Also one thing I notice with that THX speaker I mentioned. The ports on the mains look like they are the same size as those on the subwoofers that the manufactor sells. I wonder if that could have something to do with it.
 
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