can a car amplifier be set up in a home??

**hali098** · 07-27-2007, 12:45 PM

hi,
I have a 800w car amplifier, and was wondering if it could be set up in a home. I know the basic setup for a car amp, I have a power supply (12v at 10 amps), and I am using another power supply (12v at .75 amps) for the remote lead. It won't seem to power up. I have never actually confirmed that the amplifier is good, so I don't know whether the setup is bad or the amp?

THANKS!

**DarquePervert** · 07-27-2007, 01:05 PM

Yes. You need a 12v DC power source, which you state you have. Assuming that the power draw from teh amplifier is lower than the output of your power source, you should be able to get the amp to power up.

**KB5WID** · 07-27-2007, 01:27 PM

If you look at the calculation P=I*E you need around 67Amps to provide 800Watts at 12V.

Your Power supply is not big enough.

**scott_fx** · 07-27-2007, 02:26 PM

Originally Posted by KB5WID

If you look at the calculation P=I*E you need around 67Amps to provide 800Watts at 12V.

Your Power supply is not big enough.

bingo

**Rob Withey** · 07-27-2007, 02:47 PM

Originally Posted by KB5WID

If you look at the calculation P=I*E you need around 67Amps to provide 800Watts at 12V.

Your Power supply is not big enough.

It won't draw that unless you turn it up loud. It should power up on much less.

**KB5WID** · 07-27-2007, 11:06 PM

Originally Posted by Rob Withey

It won't draw that unless you turn it up loud. It should power up on much less.

Car Amps do not have volume controls like home amps. They just amplify the output of the headunit by a certain factor. It usually takes more than 10 amps to fire up. Hook the amp up to a car battery and put a 10 amp fuse un the holder. I bet it blows the fuse. Then you can place larger fuses in until the amp powers up without blowing the fuse. This will tell you the minimum powersupply size. Most auto amps I have seen require more than 10 amps for initial power.

**Rob Withey** · 07-28-2007, 03:31 AM

Originally Posted by KB5WID

Car Amps do not have volume controls like home amps. They just amplify the output of the headunit by a certain factor. It usually takes more than 10 amps to fire up. Hook the amp up to a car battery and put a 10 amp fuse un the holder. I bet it blows the fuse. Then you can place larger fuses in until the amp powers up without blowing the fuse. This will tell you the minimum powersupply size. Most auto amps I have seen require more than 10 amps for initial power.

Most amps I see in general don't have volume controls - I can't remember the last time I saw an amp that put the volume control in the feedback loop. They pretty much all rely on attenuating the input signal (just that home amps have it built into the box - it is still separate from the amp circuit). When I say don't turn it up, I mean don't feed it with a large input signal.

I'm guessing the startup current must be related to the inrush current on the power supply - must amps boost the 12v to increase the power drive capability with a boost switcher.

Otherwise with a 24v swing (bridge configuration), you're going to need a really low impedance speaker and high amperage drive capability to get 800w.

<Naive DC based calcs>
V = IR
P = VI
P = V^2/R (where V = 24)
</Naive DC based calcs>

**Cinfraco** · 07-28-2007, 05:52 AM

Yes a car amp can be run in a home application. But the biggest question comes to mind of why?
You need a 12 volt power source capable of providing enough power for that amp. The easiest way to find out what amperage you should provide is to add the fuse values on the side of the amp together.
As stated previously you need a volume control for the amp. If you have a pre-amp for system then it will work fine. Or you can run it out of a reciever, which will give you control. There is also an inline volume control module available that you can place on the RCA line.
available here: http://www.cardomain.com/item/PERPRC1

What are you planning to power off the amp? Car audio amps typically have greater THD than home theater amps. I am guessing since you say it is an 800w amp that it is a class D amp, and the RMS is about 400w. If it is a class AB or A amp then the THD will be much better. The other thing to take into consideration is the ohm load of the speakers your wiring up to it. Home theater speakers are typically 6 or 8 ohm. Car speakers are usually 2 or 4 ohm. Using higher ohm speakers will significantly reduce the power output of the amp.

**hali098** · 07-29-2007, 12:51 PM

Thanks for all your help! I still haven't gotten it running, but at least I know whats going on now.

**mrhonnesty99** · 07-30-2007, 02:26 AM

Hey when i siold my car i had 2 amps,2 12;s amd a 5 sattelite speakers running from a $30 12volt battery i got from autozone i also picked up a battery charger for another $30 and that seem to work for me. my 2 amps never lacked power.