Here’s the scenario: You have a home theater system with surround sound. On the back of your stereo there is an RCA output for the subwoofer. However, the problem is that your subwoofer has 2 stereo wire connectors on the back, a positive and a negative. So what can you do? I’ve encountered this problem myself and fortunately I have a few answers for you.
What you have is a subwoofer with a passive connection. What your stereo expects you to have is a powered subwoofer that has either a built in amplifier, or a subwoofer that is connected to an amplifier.
First off, you are probably wondering if you can connect the subwoofer to the RCA output with some kind of adapter. The answer is yes, BUT the volume that comes out of the sub is so low that it is barely audible, if at all. You won’t damage anything, you just won’t be able to hear any sound from the sub and it will be useless.
The reason for this is that the RCA subwoofer connection of the back of your stereo is meant for an a subwoofer that has an amplifier either built in to it, or a subwoofer that is connected to an amplifier. Either the subwoofer with the amplifier built into it connects directly to that RCA port (the subwoofer it’s self will have a connection for an RCA cable), or an amplifier connects between the subwoofer and the stereo through that RCA port.
But don’t worry, all hope is not lost, you have two options.
OPTION A) What you could do is go to your local Radio Shack or Walmart and buy a cheap amplifier for your subwoofer. If you have money for something expensive, then I suggest just buying a whole new subwoofer that has an amp built in.
OPTION B) The other option, and the one I tend to use in these situations is to connect the subwoofer to either the left or right speaker output, just like you did for your other right and left speakers using normal stereo wire. Now you are probably wondering, if the right and left speaker are already connected to the right and left speaker connections on the stereo then how can i connect the subwoofer to one of these?
Well if your stereo is a good enough quality one that it has an RCA port for a powered subwoofer, then chances are it actually has at least 2 connections for the right speaker and the left speaker. One group of connections will be for an entire surround sound system. You will see the front left, front right, back left, back right, center, subwoofer, and possibly a few other connections.
There very well may be another two connections that are just plain old left and right stereo speaker connections, as you would see on any old stereo. You can connect your subwoofer to either the left or right one of these. You may have to play with your stereo settings to turn on those speaker output though.
This will work decently well, it will not sound as good as if you just went ahead and bought a powered subwoofer like your home stereo expects you to have. The subwoofer is built to only output low tones, thus when you connect to the right or left speaker connection, your subwoofer will only output the low tones from that connection and give you some bass, not great bass, but it should still enhance your movie watching experience.
I hope this helps!