This speaker uses dual drivers for the woofer portion, but I decided to stick with a standard three-way design instead of a 3.5-way design. This was mostly due to the low crossover point, but also to keep the impedance at 8 ohms throughout the entire woofer region. In general, it becomes exponentially more difficult to design a crossover as more drivers are added. This is primarily due to the interactions between the high-pass and low-pass filters on the midrange drivers. One of the best ways to reduce the difficulties in this regard is to allow the midrange to cover a fairly wide frequency range. In this particular design, the midrange is playing from about 400 Hz to 3 kHz, which is almost three octaves and keeps the interactions to a minimum. Because each driver is being used well within its natural range, the acoustic crossover point and slopes stays fairly consistent with the predicted electrical models.

The woofers use a second order low-pass filter, which creates a 12 dB/octave slope centered around 400 Hz. The midrange uses a second order high-pass filter, which electrically starts higher in frequency, but which eliminates a bit of a hump in the 600 Hz to 1.2 kHz region. The midrange low-pass is a second order filter at about 3 kHz, which again because of the naturally extended top end response yields roughly second order acoustic rolloff. The tweeter comes in at around 3 kHz with a standard second order filter. Reversing the polarity of the midrange created deep and well-defined nulls at the crossover points, indicating good phase coherency between drivers in the crossover regions. The padding resistor on the midrange driver is more to help shape the response than reducing the actual output of the driver. In reality the sensitivities of all three drivers is a near perfect match.