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1802 sub port experiment


AHall

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6 minutes ago, Chris A said:

What is the longest dimension of your listening room?  This will determine the transition to "pressure zone" region or band.  In my room, that transition happens at ~14 Hz...calculated using:

 

     1132 ft/sec / (2*39.5 feet))--a half wavelength calculation. 

 

Above this frequency band, you've got the "sparse mode region" of the room (usually up to 100-300 Hz, depending on room volume and reverberation time), and above that, the "dense mode region".  At the commercial cinema scale, there is no real "transition to pressure zone" due to the room's dimensions since they are quite large by comparison to home hi-fi sized rooms.

 

Chris

My Room is 19'6" L  x 14' W x 9'H

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Then that's about a 29 Hz transition frequency. 

 

Of course, I can't tell you what happens in terms of measured frequency response of subwoofers at that frequency, but I can tell you that below that frequency, bass response no longer behaves like waves sweeping across the room, rather it's more like living inside a drum (or the interior of an automobile).  Anything that "hits the drum head" below that frequency will more or less instantly pressurize the entire room.

 

From a source, the effect of the pressure zone in terms of "cabin gain":

 

Quote

Once this magic frequency is reached [i.e., the transition to pressure zone], bass output will increase by about 12 dB/octave below that frequency [relative to full or half space response].

 

Chris

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