2.1 from 2.0 system

[Aquinter]

Hi

I'm making my own sound system with a combination of speakers and amplifier I got.
The speakers are full-range, but of course are not that good on the low frequencies.
Since I have a woofer laying around, I thought it would be nice to make a 2.1 set, sending the full-range audio to the small speakers, and only the bass to the woofer.

The output of the receiver I got only outputs 2 channels, eliminating the option of simply connecting the woofer to it. What I was thinking is to merge the two channels parallel over the speakers, and sending this through a low pass filter to supply to the woofer.

Is this possible in any way? I included an image for clarity.

Thanks in advance

 

[americanaudiophile]

That arrangement will work with a passive summing low pass filter but you will have no way adjust the level of the sub to balance it with the full range speakers. You could add a speaker level volume control to whichever plays to loud. I would add a subwoofer plate amp like this:
http/www.parts-express.com/cat/subwoofer-plate-amplifiers/332