My sub connects with speaker wire but reciever has rca..what do I do

[Brian_200]

I have a omniphase 5.1 speaker set and just got a Phillips model fr965/17

 

[jsmithepa]

That signals your sub is un-amplified and you are probably looking at a SUB OUT jack on your receiver, this signifies this Receiver, as most of them do, expect to talk to an amplified sub. The missing item here is AMPLIFIER, specifically a mono amplifier, ideally designed for a sub. Like THIS.