My little stereo to mono box

I needed a way to "sum" a stereo line-level signal from my amp into a mono signal into the amp for a passive subwoofer. I had a little project box, some RCA jacks, and some extra 499ohm resisters sitting around. It seems to work well.





With this little box, my "Bucket Sub" project is complete!

 

Congratulations. I presume that your line-level outputs are not also being used individually (e.g., as stereo inputs to a power amp), right?

 

Bifrost to amp via stereo RCA. The amp has a loop-out, and I connected those to the little box, then to the sub amp. The sound appears to be stereo at the speakers. I used a channel identification track to confirm. Do you think how I have this set up might cause a problem?

 

My concern was that if the outputs feeding the sub were also feeding your main speakers, you would have high levels of channel crosstalk: R signal into your box's R input, passing through BOTH resistors to the box's L input, and from there to the L speaker -- and the same for the L signal into the R speaker.

Since the sub is being fed from a tape-loop output that's separate from the main speaker outputs, that crosstalk is not an issue.