Hello, my friend is selling me a pair of Polk RT7 in MINT condition with original box and papers for $150. I would like to know if any member here have or had these speakers. How big is the 7 1/2 driver (outside diameter). all information and pictures of these speakers will be appreciated. I am not so sure ,but I think these speakers use first order crossover. I would like to put a zobel network (impedance compensator) if I buy them, but I do not know the impedance of the woofers. if it is a 8ohm driver I would use a 8ohm resistor with around 15uf cap approximate. But the problem is I do not find any specifications of the drivers to calculate the noble network.