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S2Ma for summing rca left/right to single input for subwoofer

Posted: 4 years ago Quote #866
Hello Edcor,

I'm looking for a way to sum up two rca inputs (left/right) into one that I can pass to a single rca input on a subwoofer.  I _think_ the right product to do that is the S2Ma.  Is that correct?
Posted: 4 years ago Quote #867
As long as it is line level, yes. The S2Ma will allow you to lower the level, but not give it any gain. level gain you would need a pre-amp.
Brian Weston
Tech Support
EDCOR Electronics Corporation
Posted: 4 years ago Quote #868
Thanks for the quick response Brian.

I think that's going to work perfectly.  I do believe it's line level as the source signal is from the tape out on a pre-amp. Currently, I barely have to turn up the powered subwoofer to get high volume so only being able to lower the level is not a problem.
Posted: 3 years ago Quote #873
OK, so I got the S2Ma in this weekend and I've tried it out, but unfortunately it is humming at 60Hz.  My situation is:

* Tape out from pre-amp to S2Ma via left and right rca
* Output from S2Ma to subwoofer Left/LFE input (or right, doesn't matter)
* Without the S2Ma in the middle, no hum
Posted: 3 years ago Quote #874
I am sorry to hear that you are having problems. Because the S2M is not an active device, I am not sure would it could inject a 60Hz. hum. That is the hum derived from a active Device's power supply. Some consumer devices can not handle an inductive loads. Have to contacted to manufactures of the components to see if they can handle an inductive load on the input/output?  
Brian Weston
Tech Support
EDCOR Electronics Corporation
Posted: 3 years ago Quote #880
If the sub has both left and right input jacks that are line level then you can connect the stereo output directly to it.

What could be happening is this.

If the ground of the primaries on the matching transformer are not connected to the ground of the secondary on the matching transformer then that may cause hum in certain situations.

Suggest taking a wire and temporarily bridging the input ground and output ground. With RCA jacks it is as easy as touching one wire to the input shell and the other end to the output shell.

If the hum goes away you will need to find a way to make that connection permanent.
Posted: 3 years ago Quote #881
Thanks Justin, that seems like a useful and easy to try suggestion.  Unfortunately I no longer have the S2Ma to test it out.
Posted: 3 years ago Quote #883
You're welcome
Posted: 3 years ago Quote #922
Having the same problem here with the S2Ma. When placed in line with the stereo RCA unbalanced output of a Sonos CONNECT unit and the mono RCA unbalanced input of an amplifier there is a loud buzz. No buzz present when the S2Ma is removed from the equation. What is the solution? Jerry-rig a wire between the RCA sleeve at the Sonos and RCA sleeve at the amplifier?
Posted: 3 years ago Quote #923
I am not sure what the issue would be. connecting the two sleeves of the RCAs could allow the ground to follow through and not keep them isolated. I would use Justin idea of connecting them and seeing if they need to have a ground follow through. The S2M isolates the input and output grounds. This helps with any type of ground look problem, like a isolation transformer does. But, some units do not ground the signal input and expect the source to ground it. This could be causing the issue.
Brian Weston
Tech Support
EDCOR Electronics Corporation