I thought I would like some music while riding my bike, but I really wanted to try it before I paid big bucks for a fancy motorcycle sound system. I had some old PC speakers sitting around and I thought to myself, "I wonder if they would work on my bike?". I checked the voltage of the AC adapter and it was 15 volts DC. My bike charges about 13.8 to 14.5 volts, so it looked like a good match. So I cut off the AC adapter and I bought a cigarette lighter adapter (male) and wired it up. I already had a cigarette lighter adapter (female) on bike for my GPS, so this was a pretty easy installation. The hard part is finding a place to put the speakers and making them secure. The Altec Lancing speaker system I am using has a built-in amplifier, so that was another part I did not need to buy. I already had a MP3 player with lots of music loaded. The system sounds pretty good. Passengers report they can hear it up to about 35-40 mph. I can hear it up to about 55-60 mph. After that, the wind noise takes over. You can not beat the price. It was zero for me as I just used parts laying around.
Enjoy the video.