Does my power supply really need 140A?

[jodyboy]

First of all I've been searching for hours on the internet (forums like these are usually a last resort for me because I know I'm just another dumb noob asking a question)

Anyways, I'm setting up my car amp/sub in my house and I'm trying to find a power source for it. I've already ruled out bringing a car battery in my house.

I have two options: Make a power converter myself or buy one. I've made small level stuff before but nothing like this. Either way I need to know...

My amp (MB Quart Onyx 1500.1, specifically 1000W RMS @ 2 ohm) uses two 70A fuses. Does this mean that it draws 140A current? I can't imagine that this is true because that's a lot, but I can't find any logic to disprove it. The subwoofer I'm choosing to run is 750W RMS @ 2 ohm.

Basically I need to know much much amperage my power source would need to be capable of having.

Thanks in advance for all of the help.

 

[DUG]

Well, let's make some general assumptions.

If you have a class D amp at 750W output running at 85% efficiency then you need 882W of power for your amp. ( 750 / 0.85 )

If you have a DC-DC converter to produce the supply for the amp running at 85% efficiency then you need 1038W supplied to that DC-DC converter. ( 882 / 0.85 )

At 12V that would work out to be 86.5A. ( 1038W / 12V )

You can change the efficiency numbers and the 12V supply to match your needs but that is how you can get a reasonable idea that you need a lot of power to make a lot of power.

Hope that helps.

(If the amplifier is not a class D then the efficiency number would be lower. Class AB <70%.)

🙂

 

[Enzo]

Numbers alone don't mean much, so don;t look at numbers and ignore the context. 70 amps may SEEM like a lot of current, but your system runs on only 12 volts. If it ran on 120 volts, the same amount of power would only need 7 amps.