Help with Resitor?

I'm trying to set up a simple two way speaker system using the following
components.

Two SR powered speakers and Two Turbosound Powered bass bins.

Both fed from line out mixing desk.

What I want to do is limit the amount of bass frequency to the SR powered
cabinets without using an active crossover.   I can feed a signal to the
bass bins, which in turn has its own crossover, which has a line out to the
smaller top speakers, but I want to reduce the bass frequency - I've read
that you can just put a resistor in line to the smaller speakers that will
do the job.

Now I've a good working knowledge of electronics, but theory is not one of
them.  Any ideas welcome

Paul