Need Help In Logic for Car Stereo Amps

[jollyrgr]

My brain is in neutral or something as I can't figure out this simple problem.

Let's say you have a standard car stereo and want to design it for high power. The max DC power supply voltage for a typical car will be 14VDC, assuming all is well with the charging system and the car is running.

Using P = (E^2)/R, and using 2 Ohm speakers you'd get:

P = 196/2 = 98W or just under 100 watts. Now I know you can bridge amps but that is still the same max voltage into the same load.

If you were to use step up transformers on the outputs you could step up voltages into the 2 Ohm loads but you get progressively higher reflected loads on the transistors/ICs used in the amps.

I'm also aware that amps will be rated for 400 watts* where the star reads (4 channel, 2 Ohm loads). How do you get the super high powered amps with only 14VDC max?

[Mike]

You don't.

The max power of a 14V supply is somewhere around 15W (I believe) into either 4 or 2 ohm (again, can't remember fore sure).

For example, I bought a so called 1600W amp at a garage sale. Pop it open and see two stero chips running on the input voltage. It's physically impossible to get 400WPC out of little chips running at 14V.

To get more power, you have to boost the power up. There's no way around it. If there was, I would have built my own car amp.

[Chris Smith]

There are many ways to rate a watt speaker system, and mostly, that is what they do.

Rate them all sorts of [cheating] ways!

Peak power can be had by using super caps to deliver, when the moment arises.

Step up convertors in the amp can supply 50 volts or higher to the circutry, and with a sufficient amp delivery system [super caps and large leads] you can provide any amount of amps/watts to the speaker system, ....period.

Its called trading curent for power/watts.

If you have 14 volts and 100 amps available to the amp, you have the potential for 1400 watts of out put, .......minus the R losses.

But to make this actually happen, you first step up the voltage way above 50 volts and use the high voltage to deliver the lesser current, much like our house hold AC wiring.

One amp at 100 volts is 100 watts.

[Robert Reed]

Jolly
"I'm also aware that amps will be rated for 400 watts* where the star reads (4 channel, 2 Ohm loads). How do you get the super high powered amps with only 14VDC max? "


I think you answered your own question. The clue here is " four channel". If in fact you do get 100 watts per channel as per your calculation, Then four channels will give 4 X 100 watts = 400 watts total.

[Tommy volts]

When the next door neighbor's kid drives by our house, his windows rolled up, our windows and doors closed, the power of his stereo still rattles our 2 story house with bass thumping.

It seems like there must be some serious power there somewhere. It also seems like all the music players in kid's cars these days have that kind of power. How are they getting that power?

[Chris Smith]

They use a second alternator, second battery, and super caps of values of one farad or more for the base response.

The old saying is you dont need to run your heater in the dead of winter because your stereo will keep you warm, just like the old days of the linear running at 4kw in the trunk.

[Externet]

Those true 14V high powered amplifiers have a voltage step-up booster inside their housings to provide usually plus minus ~80 Volts to run the amplifier section in them.
Miguel

[JPKNHTP]

-JPKNHTP

[Chris Smith]

Adding more batteries and alternators allows these amps to draw 50 to 100 amps, with out effecting the cars battery and alternator system.

A lot of the amps are a joke, the legit ones convert amps to volts while the super caps supply the momentary BOOM BOOM for the base.

The Fets units amps I have are suit case in size, [you almost need a fork lift to install them] and they are actually rated at 140 watt, 280 watt, 400 watt and 600 watts.

Their heat sink dimensions are almost two square feet, and their feed wires are "battery" size cables in the "0" to "00" gage in dimension.

The Fets when removed and recycled can power your hybred car,.... almost?