There are a few threads on this but I'm having som issue finding a straight answer, and the necessary instructions. Here's the situation...
We just finished a new TV Room and wired in all the speakers. Until this week I didn't realize the wiring for the sub was 16 gauge speaker wire. I of course needed COAX cable. The placement of the sub is some 30ft from where the AVR and the rest of the components sit (inside a separate room).
So can I use the 16g speaker wire coming out of the wall as COAX? Assuming I solder an RCA plug to either end? Or am I hooped?
You may be "hooped" but you should try it. The likely problem is not signal strength but noise pickup and that is highly specific to the situation. Try it and see as you have little to lose.
If it is unsatisfactory, you can try to pull a coax cable using the speaker wire or you can add a wireless link. I have used the AudioEngine W1 (now discontinued) but there are others.