What's a good and efficient 12v sound system?

[fireofenergy]

I want to completely bypass the inverter to power led lighting, a laptop and SOUND system with just 12v batteries.

I know it is really simple to make the most efficient led lighting by using four Cree XP-G's and a low ohm resistor in series.
I assume Newegg sells car (boost) adapters for most laptops...
But isn't there a way to do better than a power hungry car stereo system without having to build it myself?
Thanks

[Mike90250]

I'd say look for a Automotive stereo, in the 5 - 10 watt/ch range. Use it to drive some efficient speakers, and you can shake the fillings out of teeth at 20 feet.

Don't get so wrapped up in POWER WATTS, that you loose sight of EFFICIENCY. Why pump 100 watts of power into inefficient speakers, when 5 watts will be just as loud, with efficient speakers.

With solar, it's all about doing things efficiently.

[Mike90250]

...I know it is really simple to make the most efficient led lighting by using four Cree XP-G's and a low ohm resistor in series. ....

Wrong. That is the simplest way. Resistors = heat = loss.

The most efficient way is with a LED driver circuit, that can take 12-16VDC input, and power the LED. Basically a Constant Current Driver. LED's run from current (amps) not volts.

A simple resistor will burnout the LED's when the charging voltage is high. Someday, somebody, will leave the light on all night, and when the sun comes up to charge the battery, poof!

[fireofenergy]

Thanks for the info. As for the leds, I have already done the resistor thing and "sized it" for 14v (and still less than led max current). Then, when the battery gets down to 12v, it's really dim, for me, a nice low battery indicator.
The driver idea (used it too) can only drive three leds from the 12v... then the battery DOES get too low (because each led's forward voltage is only 2.8 to 3.3v). In this case, I'm just talking batteries for the lights.
However, the driver is better as long as it isn't connected to such a small battery as it is constant current, I'm just afraid it could all of a sudden shut off without warning by the controller.
Edit, and I can't find a led driver that "starts" at 12v. That would be wonderful !

[Wy_White_Wolf]

Something to consider is where the music is coming from. Playing CDs will require more power than listening to the radio or playing from an MP3 memory stick.