Using test tones
 

I want to set my gain for my sub using a 50hz test tone to . The thing is, the test tone will be playing through all my 4 of my cars speakers. (my sub being the only thing connected to the amp, the rest of the speakers connect to the HU) Would this be bad. I heard if you play too low frequencys through normal car speakers they'll start to smoke and die. (the front speakers are Pioneer TS-164P and the rear are jvc 6 1/2")

This is why we have HPF's, your deck should have one built in.

your speakers may 'fart' on you and could definatly be damaged...... on 20 watts ? I hope not........

still I think it would be best to get a 50hz tone (or whatever) on your cd player, cell phone, whatever.....and hook that up to your amp....

I thought the whole point of setting the gain was to match the output of the HU to the amp, wouldn't using an mp3 player defeat the purpose?

If your really concerned about damaging your speakers just pull your deck out of the dash and disconnect the speakers wires from your deck so that its just your amp connected to it. Then you can set gain on the amp and connect the speakers back after your done.