LED light bars sync to music

I have two 12V blue LED light bars. I need an electronic circuit that I can connect to my amplifier that will make the two LED bars synchronize to music.
I have researched a little bit online and I understand that I need a transistor to amplify the signal, but other than that I am not really sure what I need to do.

I don't know how many LEDs are in your "light bar".
We use an LM3915 IC to drive 10 LEDs in a VU meter display. Usually the blue LEDs are 3.5V, not 12V.

I used red LEDs and a microphone in my project:

I'm not sure either how many LED's there are. I bought it from the internet but the casing prevents me from seeing how many LED's there are. I am assuming that each led is 3.5V but the whole "bar" runs off of 12V.

i had some problems when i tried to make this circuit, but then again, i did try to double the circuit (make 2 of them). the first one worked fine, but the second one was weird. it would display to the input level, but then the LED's would shut off until the signal started to decrease again. maybe it was because i was using 741s instead of 324s... nah that's not it I am also unsure of where to connect the speakers. but other than that, this circuit does work

hey thanks man, im a little confused though about where in the circuit the LM324 goes...sorry i dont know much about schematics

One single LM3915 will replace the old circuit that uses two LM324 quad opamps and millions of other parts.