How do I connect a car amplifier?

I have a "300W" (actually 30W) mini amplifier. It has black, red and yellow wires for power.How do I connect it?

Re-design8 years ago
What do the instructions say?

THe red is probably positive.  THe black is probably negative.

They yellow is probably a sense wire from the radio/cd, so the amp is not on unless the radio/cd is on.  It might be pos. to turn on or it might be ground to turn on, I don't know since I don't have your amp. and instructions in front of me.
slovenija (author)  Re-design8 years ago
Instruction says I have to connect it to radio, and that's it...
It's better to try ground first, right?
And... does it need to be connected all the time or just a moment?
A modern radio should have a terminal called "amp sense" or something like that.  It turns the amp on and off.  It should be connected all the time.
slovenija (author)  Re-design8 years ago
Thanks for your help!