How to add a sub woofer to my stereo?

I want to add a sub woofer to my stereo system. The sub woofer is one made from spare parts. It consists of a twelve inch speaker wired directly to binding posts. My problem is that my amplifier only has four binding posts, these are a positive and negative for the left speakers and a positive and negative for the right speakers. I am not sure where to patch in my sub woofer. Thanks for any help

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thegeeke6 years ago
Use either, but be aware that you will reduce the signal slightly by doing so. If necessary, adjust your pan (aka Balance) so that it evens out. The more important thing to consider is whether or not there is a cross-over in your woofer. You really need a cross-over, whether it is before the line that goes into your woofer and has a direct output for the woofer, or even inside the circuit inside the woofer would be fine.
nurdee1 (author)  thegeeke6 years ago
Thanks for the info. I had thought of this but supposedly it is bad for the amp to have more load on one side than the other
Yes and no. You could build a mono bridge, but if you want it to be stereo, you will loose that. Not only that, sometimes amps with short sensing circuits can mistake a mono bridge for a short. (It's not, but it can fool them.) You shouldn't have a problem if you balance the outputs... I would do that with a solid tone sine wave. (If you want to, you could use a multimeter to be exact.)

You could solve all your problems by getting an amp that has a dedicated sub output. That way, you have a cross-over built in to the amp.

All in all, I don't think that you are really going to kill your amp by adding this, but if you are really concerned about it and you don't want to buy a different amp, build a mono bridge. (Or just don't use your woofer.)
nurdee1 (author)  thegeeke6 years ago
Thank you. I think I may build a mono bridge. My amp is a high end Carver and I don't want to buy a new amp. Fortunately I discovered tha the headphone output is isolated from the speaker output. This meens that I can make a mono bridge, and run the subwoofer along with a small amplifier on the headphone output. That way I have a mono subwoofer and still have stereo speakers for the left and right. Thankyou for your help.
Ahh... yes, I wouldn't want to take any chances with a carver either. I'm supprised that it only has two channels, but I'm glad you found a solution. Have fun! :)