Help Need to combine L and R feeds for mono amp

I need to combine the L and R channel signals from a stereo CD player, and other stereo sources as well, to feed a mono amp. Can you tell me how to build a bridge device to accomplish this - maybe send me a simple schematic?

All help appreciated.

This is for a vintage setup with HH Scott preamp/amp, Klipsch Corner Horn, Thorens TT, etc.
My local dealer says to use a buffer; they sell a buffered y-adaptor ic. Cannot remember the brand, but I'm sure it is readily available by doing a search.
Can't you simply use a splitter?

Thanks Ericjcabrera - I will look into that as soon as I get to town.

Thanks also Rlwainwright. I had tried using a reversed splitter and got poor mono signal, and then was advised by a nice person on thTs forum that doing so would cause more than one problem. Yhat individual suggested a simple "bridge" but did not give specifics. Thus, my request.

Anyone else have some info?

Try this:

1 kilohm to each output. Tie the loose ends together. Take that into your mono amp. You may have to juggle the value some, and perhaps add a resistor to ground at that common point.
Hey Ar_t - thank you. Will try.