why is are my subs so weak?

[Nate]

i got 2 rockford fosgate 12" single coil the put out 150 rms per sub at 4 ohms and then i got a kicker 2 channel amp that puts out 150 rms per channel at 4 ohms i installed these into my car myself and it worked great for about 2 days. just today i was driving and noticed that my subs got really weak almost to the point that it wasnt noticable but there was no red light on my amp. i turned off my car and turned it back on after 10 mins or so and it worked for a few mins and got really weak again i checked all the connections they all seem fine. i dont think the speaker is blown i was also thinking that it may b my really cheap box that i bought for em im really not sure and would really appreciate any advice people may have to offer please help

 

[Tim]

So your saying your subs are less loud after driving around for 2 days and cutting your car on and off fixed them really it could be 2 things you could just be getting use to the bass so it seems like their not as loud as when you first installed them or Your bass is getting less loud because your alternor isnt letting your amp enough voltage the less voltage your amp is getting the less watts of power your sub is getting so its not going to be as loud as if you had proper voltage to your amp i'd reccomend getting the battery and alternator checked at your local auto store and if they check out maybe you can upgrade your system if you want because your just use to it

 

[Jason]

sounds like the speakers are fine, it's probably the amp, head unit, or battery.