Onkyo 606 Crossover

[GeneD5]

I've got the Onkyo 606 and Polk rm6750 5.1 setup. My woofer is pretty much only doing very deep rumbles and nothing more. Talking to an a/v guru that I know, he said to set the crossover frequency up to 120hz (as the polk guide also suggests) so that the sub gives off more kinds of sound other than just the super-low end. That being said, where the heck can you do this on the 606??? I've found the db settings, have gone through the manual, and can't find this setting. It shows "hz" speaker settings for every other speaker but the sub (p.s. I did the audyssey straight off and this is where I'm at still)