Car Stereos: subs or alternator, 4 ohms, dereck

Question
hi ive got a prob when i barely turn up my stereo my subs cut off but my front speakers( not connected to amp)stay on  thought it may be subs but when i tried to start car up after 2 weeks batt was dead just bought batt 2 months ago never replaced alternator could this be the prob.?

Answer
Hi Dereck,

When amps turn off, it means one of three things: they're overheating, they're not receiving as much impedance as they require to function, or the amp is shot.

Amps can overheat from bad ventilation, or from being overworked.  You're suggesting it happens when you barely turn them up, so I'd suggest that being overworked is not likely to be your issue.

So we move onto impedance.  Make sure your subs are wired in a configuration that is providing the correct amount of impedance (or higher) that your amp requires.  If your amp says it is capable of 4 ohms, and you're running 2ohms to it, it will not like it, and it will shut off to prevent damaging itself.  If it says it can handle 2ohms, but you're giving it 4, that's OK.  If you're unsure, get a multimeter and check the amp's specs.

Justin