Need help using a subwoofer crossover


I have a cheap Velodyne CT-120 sub. I am trying to experiment by using its crossover to prevent my main speakers from having to reproduce frequencies below about 100-120 Hz.

The back of the sub has RCA input and output terminals. I ran cable from the "main out 1" on my pre to the input terminals on the sub, then ran the output on the sub to the inputs on my amp. Result: I get sound out of the sub but nothing out of the speakers.

I have the low-pass filter set to 120 Hz, and sub is on all the time (as opposed to auto). The only thing I can think of is there is a high-pass filter switch on the sub that can only be set to 80 or 100 Hz. I'm wondering how to engage only the correct filter so my speakers run everything above 100 or 120 Hz.

Any ideas on what I'm doing wrong?

Thanks tons!
Howard
aggielaw
Thanks for the input, guys. I tried running in and out from the speaker-level in/outs and it worked fine. It leads to another question that I'll ask in a different thread about how the crossover and amp interact.
Curious how you made out with the crossover settings? My understanding is that the crossover setting on your sub will not affect the signal that your main speaks receive.
What was your outcome?
Hifi,
I wound up buying an ACI Titan and a Marchand XM9 crossover. Life is good, but I'm already wondering what an even better sub and main speakers would do. :)