- Crossover Design -
As established in the goals section, the crossover design is
an integral part of the success of this speaker. I employed
a somewhat unique approach to the crossover, namely
what could be called a 2.5.5 way design. Basically, the
outermost drivers operate up to about 200 Hz, the middle
drivers operate up to about 700 Hz, and the innermost
drivers operate up to about 2 kHz where they cross to
the tweeter. This approach allows all of the drivers to
work together at the lowest frequencies for maximum
low-end extension, while only the innermost work at higher
frequencies for maximum dispersion.
To achieve the desired impedance, the speakers are wired
with two drivers in series, and then each of these pairs in
parallel. The outer two drivers are in series with each other,
the middle two are in series, and so on. The net result is
an impedance of 5.33 ohms, which once some inductor
DC resistance is added results in a nominal impedance of
6 ohms. This impedance combined with the high overall
sensitivity should work well with any home theater receiver,
even if it is rated for an 8 ohm minimum center channel.
The tweeter crossover is a second order high-pass with
a very small padding resistor that reduces the output by
a couple dB. This design is unique in that the tweeter
is connected in reverse phase compared to a "normal"
two-way design. The result is excellent off-axis response
in the horizontal domain-- far superior than what would
be expected.
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