I have a 12" JL W0 sub in a sealed enclosure in my trunk. I have noticed that when I turn the music way down in my car or I pause the song, the sub will pulsate, looks like it is breathing. I took out the card board piece from behind the armrest and the sub fires through there so I can see whenever it does it. I have an Alpine V-12 amp(older one) and I have tried adjusting all the settings but the only thing that wil work is when I turn the gain all the way down, but then I have hardly any bass. What is causing this? Thanks!

 

well soemtimes if the subs try to hit low notes, it'll puslate, that's not a bad thing. as for when you pause it, I'm not sure why it's pulsating..maybe you have a bad signal?

 

I had a v-12 amp for a week it was ok!! it draws alot of power though, and if the gains on the amp are turned all the way up, the amp may be clipping(trying to pull more power than the car has to give) so try turning down the gains slightly. How many watts is the amp?

 

Red's right. I have a v12 1000, 500, and 400 (4ch). I only use the 1000 for subs and 400 for front. I had to hood up an optimus batt. and a capacitor and that seemed just to cover the consumption. Try a capacitor. So, what is the size of your amp and how is it wired (directly from battery)?