hali098

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!

MP3Car.com

 

DarquePervert

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.

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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.

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scott_fx

bingo

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Rob Withey

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

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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.

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If It's Called Tourist Season, Why Can't We Hunt Them?
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The Definition of an Upgrade: Take old bugs out, put new ones in.
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Rob Withey

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>

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Cinfraco

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.

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hali098

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

mrhonnesty99

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.

helllordkb

yeah i was thinking, would a DC car battery charger put out enough amps to run the car amplifiers in the house? and just wire there power/ground to the dc car charger?


or do you think the trickle or slow charge most do, will only charge it at very low amperage

blafrisch

Are you talking about a wall wart? There is not a chance in hell that it would put out the amperage you'd need.

You need something like on this page to power an amp, making this idea rather impractical.

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helllordkb

you would need somethign like this http://www.batterystuff.com/battery-...2-volt/21amps/

thats what i was talking about

Cinfraco

Look at the prices of the DC inverters. For the amount that you would spend on getting this set up to work right you can get a home amp of about the same quality as the car amp you are trying to use. For about $300 you can buy the low end of the Denon amps. You can do better than that if you buy used.

The other option is to build a 12volt inverter. This can be done for about $50, with parts form digikey.

helllordkb

lol im not sayign its a good way.. its very stupid to do that..... i wouldnt ... id just use a cheap marine battery for a trolling motor and when the battery died id recharge it. totallly areee not worth it even then though. id rather just put it in the car and see if it works, if not i replace it.

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