The network I use in my speakers will work for you, using values R1=16 ohms, R2=30 ohms and C1=0.47uF. It is a little different configuration than usual, with the shunt resistor in front of the series resistor, because it was designed to provide a specific amount of damping for my crossover. But it will work for you very nicely. Load impedance is about 12 ohms, so keep that in mind when choosing your crossover cap.