# Summing stereo and mono channels passively

I am trying to build a headset for use on my motorcycle which will allow me to listen to my music from my phone (stereo signal) and the incoming sound from my UHF radio (mono i'm pretty sure). what is the best way to passively sum these signals? i wont really need mixing control as i can alter the volumes from the uhf controls.

• Using resistors is a common method of combining left and right. I'm not suggesting it will work well for you. I'm not suggesting any particular resistor values, just yet. But it is commonly done to produce mono from left and right stereo. – jonk Aug 28 '20 at 9:41

• L music $$\\rightarrow\boxed{\text{ 1 kΩ }}\rightarrow\$$[L output]$$\\leftarrow\boxed{\text{ 1 to 10 kΩ }}\leftarrow\$$ Mono signal
• R music $$\\rightarrow\boxed{\text{ 1 kΩ }}\rightarrow\$$[R output]$$\\leftarrow\boxed{\text{ 1 to 10 kΩ }}\leftarrow\$$ Mono signal