16
When coupled with an active high pass filter, this switch will allow a bit of
slope contouring for acoustically blending with the sub.
The system also compensates diffraction loss by applying approximately a
1 dB/octave roll-out (with rising frequency) in the woofer stage. This is
verified by near-field measurement of the woofer. While the impedance
curve implies a box tuning frequency of 32 Hz, the rear port actually
achieves maximum output at 45 Hz. Tuning the system a bit lower allows
a slightly lower cutoff frequency at the expense of some output, thus
allowing the speaker to take advantage of a bit more room gain without
peaking the frequency response. Switch 2 provides a tweeter pad of 2.5
dB for near field listening.
In set-up, I recommend a speaker spread of about 7 ft for a listener
distance of about 12 feet. The speakers should cross behind the listeners
head (don’t toe-in excessively).
The bottom end will be determined primarily by the distance from rear wall.
I feel they can reach down to low E as anything near the size.