Combining two audio sources into one set of headphones

[R1200RT]

Thanks for reading. I want to do this "professionally". I ride motorcycles cross country. Mounted on it is a radar with an audio out headphone jack. I also have an iPod in the pocket of my riding suit. I have high quality, molded racing type, headphones and want to maintain good sound quality. I believe the way to define the jacks is "mimi, 3.5mm". Basically I want to hear music out of my iPod while being able to listen for beeps my radar makes all through one set of headphones. Ultimately I want to be able to adjust the volume of my iPod while I'm listening to music and also be able to hear "beeps" cutting in from my radar while being able to adjust the "beep" volume independently of the iPod. Any advice would be great.

Thanks,
Jason

 

[BobK]

If each of the signals is strong enough that you would never turn it up all the way, you can do it by simply putting a resistor in series with each and connecting the two together to go to the headphones. The resistor should match the impedance of the headphones. Typical headphone impedance is 32 ohms, so 33 ohm resistors would work fine. The grounds from the two signals must be connected together.

Bob

 

[poor mystic]

If on the other hand you need to preserve all the power you can (and get the loudest possible signal) you'll need a mixer.
Mixers can be however good or simple you want. BobK's idea is a mixer of sorts, but amplified mixers are much more complex and expensive.
I think it likely that some company makes a tiny professional mixer for the use of guitarists on stage. I envisage a foot-switch controlled, battery powered unit. I bet they're not cheap, but they'll be designed for hard use.

Oooh! I found one on the net: http://www.americanmusical.com/Item--i-RLL-MX28-LIST