Tons of audio noise problem

**hutacars** · 09-22-2009, 06:27 AM

It's a 400 watt amp. There may be a fuse inside it, but I have not opened it yet. Then again, maybe not, considering it was a cheap amp from China

I'll check the fuse in the cable first, and if need be I'll pop open the amp and have a look.

**PaulF** · 09-22-2009, 06:39 AM

Volts x Amps = Watts

Car electrical system ~ 12 volts.

400 watts at perfect efficiency is 33.33 amps.

33.33 is over 3 times what a lighter socket can handle. You definitely blew the fuse in the cable. Run it to the battery.

**hutacars** · 09-22-2009, 08:16 AM

I thought watts of audio output were different than watts of power draw? It provides 400 watts of audio output, but I don't know the power input, because as I said earlier, there's no label that tells me, nor can I find any information about it online.

The amp is designed to be used with a cigarette lighter cable, so it *shouldn't* draw more than one of those cables can pull... right?

**ik632** · 09-22-2009, 09:45 AM

Most amps aren't designed to run off a cigarette lighter plug. You need to connect it all correctly and then see if the issue is still there. If your signal cable is running next to the power cable you will get a lot of noise too. Try running the amp with an mp3 player connected to the input. The input level will be about the same as from the computer so get it roughly setup using the mp3 player and then you should be good. Save your self some time and frustration now and just run the proper cables. For a 400 watt amp, you should be fine with some 8awg from the battery. Be sure to fuse at the battery and then fuse again before you go to the amp. For ground, you can connect to somewhere near where the amp is mounted. Finally, you'll need remote turn on either from the computer or some other source that you are using.

**soundman98** · 09-22-2009, 10:05 AM

i think some of this is assuming that the amp truly puts out 400 watts-- if it is just a cheap china amp, i would have to say that the wattage is wrong (or measured at 24volt input...).

it used to be true for car audio amps of any caliber that you could use that formula, but these days, it seems that alot of the companies have strayed to their own measurement system--mostly the cheap amp producers. for these amps, the formula does not work.

but on the other side of the coin, there is CEA certification, and higher end companies that pride themselves on selling exactly what they market (alpine and jl are 2 of the more popular companies that do this).

**summer69guy** · 09-22-2009, 11:18 AM

chek your power suply

**Phoenix750** · 09-22-2009, 11:30 AM

I agree with everyone's good input here. I'd also like to note, that if you'll be grounding your amp to the chassis, you need to do it RIGHT:

- less than 12" from amp
- avoid using existing bolts; but you can if necessary for you
- sand the surface BARE
- use quality ring terminals

Seriously, I've wasted so much time troubleshooting **** that turned out to be improper grounding. Save yourself the headache and do it right the first time.

**hutacars** · 09-22-2009, 11:31 AM

Originally Posted by summer69guy

chek your power suply

What should I be checking for exactly? The way things are currently set up, the amp is not connected to the power supply anyways, so I don't see how the power supply could be causing the issue.

**trader007** · 09-22-2009, 11:56 AM

you have made this so much harder for yourself it is insane.

take a 30a fuse, hook it to your battery's positive post within 12".

take a 4awg or 8awg wire and hook it to the other side of the fuse, then run that wire back to your amp and hook it up to the positive terminal.

take another 8awg wire and run it from the amp's negative terminal to the closest ground point in the car, usually a seat mount. do not screw this up, the ground must be 100% good.

done. do it right

**PaulF** · 09-22-2009, 12:28 PM

Originally Posted by hutacars

I thought watts of audio output were different than watts of power draw? It provides 400 watts of audio output, but I don't know the power input, because as I said earlier, there's no label that tells me, nor can I find any information about it online.

The amp is designed to be used with a cigarette lighter cable, so it *shouldn't* draw more than one of those cables can pull... right?

Watts is watts. It's a unit of power. There are no "different" types of watts. The thing is that:

Originally Posted by soundman98

i think some of this is assuming that the amp truly puts out 400 watts-- if it is just a cheap china amp, i would have to say that the wattage is wrong (or measured at 24volt input...).

But regardless, I guarantee the draw of the amp is over 120 watts.