The next response curve we have here is of an Acoupower -01 15" driver in a 3.8 cu. ft. (net) vented box tuned to 24 Hz.   See Figure 2 Below.   Again, this is a 2.83V @ 1m half space measurement.   This box is comprised of a large diameter very strong, thick walled tube.   The driver is mounted on one side of the tube, and the port openings are on the other side.   The solid line is the response on the axis of the driver.   The dotted line is the response taken 1m away from the side of the box, and toward the back of the box (much farther from the driver).   The power response is a composite of these two curves.   The slight dip in the response around 200Hz is due primarily to a cabinet mode.

Listening tests and in room measurements show that this box has a typical in room response characterized by a gradual peak of +3dB at 30 Hz and a -3dB point of approximately 19Hz.   Note that the 1m output in a room will be much higher, with up to +12 dB possible when placed in a corner.   Due to the excellent excursion management of this vented system, this driver will NOT exceed it's 100% linear BL range when driven with even 1000W RMS input.   Acoupower 15" drivers in boxes like this have been characterized as producing "effortless", "super extended", "very tight", and "totally clean" bass.  

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