Sub Phasing vs Level - AVS Forum | Home Theater Discussions And Reviews
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Old 06-24-2013, 10:52 AM - Thread Starter
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I read alot about balancing the volume level of subs to the rest of the system, but I don't see much about phasing. Most subs have a NORM/REV switch and AVRs also have a NORM/REV switch. These will shift he phasing by 180 degrees. Some subs will allow the user to adjust between 0 and 180 (NORM and REV). But some users do not realize that the sub Distance setting affects the phasing in between for fine tuning.

So, what is the best way to adjust the phasing for a system set up in a room? I read one method that says feed a tone at the crossover frequency and adjust the phasing for max SPL. I guess the idea behind that method is that the Low Pass and High Pass filters will cross at a minimum at that point, so you want to max out the output of the system.

So, I tried that method. After running some sweeps, I found I ended up with a bump around the crossover freq (100 Hz because I am using small satlllites for surrounds). But I also noticed and a bigger bump at what appears to be my room resonance around 40Hz. So I began playing around more with the distance setting of the sub to see how it affects the freq sweeps. I was able to flatten out the FR between 20 and 120 Hz. I am not saying it is flat, but it looks better. Now the system seems less "Boomy", but still has all the bass I want.

So i am looking for feedback from the group here about if there is a proper/best way to quantitativly set the phasing for a sub.
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Old 06-24-2013, 11:03 AM
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Do you have a saved graph you can post?
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Old 06-24-2013, 04:17 PM
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Changing the sub distance is similar to using a variable phase control. A lot depends on your avr and how it's autocalibration deals with speaker/sub integration. It is more complex because of speaker roll off and how that relationship is with the filters. A sub/s close to the mains are easier to integrate and not be localized than subs close to the LP. A higher xo is easier to integrate with sub/s close to the mains. Getting the bass right in a system is one of the hardest things to accomplish.
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