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Old 03-17-07, 11:42 AM   #14 (Link)
 
brucek
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Re: First real measurement subs, subs+main, subs+main large


Quote:
The critical band is between 100 Hz and 5 Khz. Below 100 Hz is not very important
Yeah, anything below 100Hz doesn't respond to room treatments or traps very well unless you involve very large physical devices. At the lower frequencies (where subwoofers play the biggest role) the wavelengths involved compared to standard room dimensions are large enough that the behaviour is considered minimum phase.

This means that primary reflections (second order) from the walls, ceiling and floor arrive at the listening position anywhere in the room with a phase shift of quite a bit less than a cycle. For example a 40Hz signal has a wavelength of ~28 feet. The limit here of about 100Hz with a wavelength of ~11 feet is reasonable for equalization..... It's important in home theater to remove the peaks caused at model frequencies to avoid low bass boominess. Multiple subs is a lofty goal that has benefits, but difficult to put into practice for most people (cost, WAF, technical ability, etc). The modal response at the listening position is easily and effectively controlled by second order filters (same Q, inverse gain) designed by REW software and implemented by a BFD parametric equalizer.

brucek


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