Please review this mono-summing

[regal]

I can't believe there are no commercial RCA stereo to mono summing boxes.

Please look at this circuit. Do I need a DC blocking cap on the output?

 

[poobah]

Depends on what you are connecting to.

 

[regal]

I will be adding this to the output of my DIY tube preamp, going to a home theater reciever

 

[edjosh23]

I have 20 of those things... I've been wondering what I should do with them.

Josh

 

[CarlosT]

Not to hijack this thread but I have a related issue. I'm trying to combine the outputs of an iPod/MP3 player into a single mono channel to feed a non-inverting LM3875 chipamp. Would a simple 10K ohm resistor in line with each + input work before summing the channels? I'm looking to do the simplest thing that'll keep me outta trouble.

Something like this...

http://www.epanorama.net/circuits/linesum.html

Does the fact the the chipamp kit is non-inverting have anything to do with anything for summing channels?

Thanks.

 

[davidlzimmer]

Seems to me, you summed them at the 26k resistors. What purpose does the op amp serve? Gain? Impedance matching? Just curious.