|
We could also get into a lot of things with impedence rise based on the box size/design, specific subwoofer model, wiring configuration, frequency being played, etc, and find that you might only be putting a few hundred watts RMS into them and dimming the lights. Power thru a resistive load for rating purposes comes out much different than power thru a reactive load (speaker). A sub setup might be rated at 2 ohms, but you could throw it in a ported box, play a 50 or 60 hz sine wave and find that the amplifier is seeing something like a 12 ohm load. So that 1200 rms really only cranks 200 rms at that point. Because of box tuning, resonant frequency of the car, cancelation issues, etc, it might be louded at that particular frequency, even though a lower sine wave my put three times a much power into the subs.
If putting out a real-world-in-car wattage of even 600 rms, an 80% efficient (class D) amp at 14.0 volts will only draw 54 amps.
My long winded pointless point is that your stereo probably is not drawing nearly the power you think it is, yet can dim lights. So a large electric fan dimming lights on startup is not that surprising.
__________________
|