What are the differences between amps used for cars and amps we use in home theater/music applications? It seems that car amps have higher power ratings with similar tolerances in THD and S/N but are much cheaper. Why not use something like
http://www4.shopping.com/xPF-Rockford-Fosgate-Power-1500bd (purely as an example not specifically this) for home based subs?
I'm sure there is a reason or more people would do it; I'm just curious what the reason is.
Thanks.
Ratings tend to be, shall we say, generous. In the past, we used to consider car amps to be rated in Watts JBF (just before fire) and WLS (when lightning strikes), because what was stated never happened in real life. Also, you would need a pretty beefy power supply to adequately run a car amp unless it's Class D. If you look at Rockford amps, they tend to have very high headroom, which means they draw a LOT of current because their power supplies don't tend to be highly regulated. I wouldn't recommend using a car battery inside unless it's truly sealed, can't possible leak and is made for high current discharge. High current power supplies are expensive and would negate any savings you would see just when comparing amp vs amp. Optima isn't what it was but if you look in some of the car audio forums, you will definitely get some ideas about which ones are better than others. The reason car amps need a beefy supply is that cars work with 12VDC and the output devices often need 60VDC or more. You can't just take 12V and make it into 60VDC but 60V is a piece of cake on a 120V AC line because a transformer can be used to step voltage up or down. In a car, the 12VDC needs to go to an oscillator for creating an alternating voltage that can be transformed into a higher voltage, then rectified into DC voltage, regulated for stability and filtered. All of this happens before the audio is even considered.
It's not a dumb question, by any stretch. It can be done but you need current and as I mentioned, a truly sealed battery set up so it can't leak (acid or hydrogen) is needed. Storage batteries work well for this and if you think a bit outside of the box, it's not hard to charge it, especially if you're in an area that allows devices on/near your house that a homeowner's association or zoning doesn't.