The lower midrange output works identically to the upper midrange output, save for the different banding frequencies.

The low frequency woofer output also works identically to the upper midrange output, except that the high pass frequency is set to a sub-audible frequency.

18 dB Crossover Circuit description
Not for the faint of heart. This circuit requires two more triodes and  12 more capacitors and 12 more resistors  than the 6 dB circuit. Still the steeper crossover slopes make it the only choice for many systems. Unlike the 6 dB version, all the crossover network components receive a buffered input by a Cathode Follower, whose low impedance output prevents unwanted interaction between networks. The networks differ in topology between low pass and high pass filters. The low pass sections of the crossover are pure textbook 18 dB filters, but the high pass sections look like 12 filters, although they function as 18 dB filters. The trick is that the coupling capacitor is used as part of filter. Since all Cathode Followers must be capacitor coupled, using this capacitor in the crossover network makes sense. This topology reduces the part capacitor count; remember, less is more. The part count is further reduced by placing the high pass sections after the low pass sections, as this arrangement eliminates the coupling capacitor from the low pass section.

Setting a different
high pass frequency:

     C1 = choose
     C2 = C1
     C3 = 1/(2•¶•F•R3)
     R1 = 1/(4•¶•F•C1)
     R2 = 1/(¶•F•C1)
     R3 = 1/(2•¶•F•C3)


Setting a different low pass frequency:

     R1 = existing value
     R2 = R1
     R3 = R1
     C1 = existing value (old F / new F)
     C2 = existing value (old F / new F)
     C3 = existing value (old F / new F)

Which Tube?
Quite a few tubes can be used in this circuit. The tube chosen was a 6DJ8 type dual triode, as it boasts both a relatively high mu and high transconductance. (Other tubes could have been used. For 9 pin fans, the choices are many:  6AQ8, 6C4, 6CG7, 6FQ7, 6N1P, 12AU7, 12B4, 12BH7, 5687, 7119,  triode connected 6BQ5, 12BY7, EF86. For octal fans, the choices are fewer:  6AH4, 6J5, 6SN7, 6BL7, 6BX7, 12SN7. Other factors in choosing the 6922 are its ready availability, sometimes low noise (many are microphonic), and low heater current demands.