this instructable will show you how to make an easy blinking LED to music.
you can try it whit normal lamp but the effect is better whit LEDs its easy to make it.I made it after 30 minutes. and after the effect is awesome

Step 1: Materials That You Will Need

you will need:
materials:
1×tip 31 transistor
2×led
1×6v transformer
some wire

tools:
soldering iron
solderer
wire cutter
scissor

Step 2: Leds

to the effect is better connect the led in serial connection. they going to blinking much better

leds.otg
Download

Step 3: Transistor

the circuit is based on the tip31 transistor you have to connect the music left to the left side of the transistor
connect the wire of the leds to the middle of the transistor
connect the music right and the negative pole of the power supply to the right side to the transistor

Step 4: Connectig to the Music (whit Rca)

grab the to wire for the music and connect the right side to the middle of the right plug's middle
the left side of the music connected to the left side rca to the middle of it.