I had the same problem use a ground loop filter and make sure the inverter and computer (power supply) are grounded to the same spot. I have no noise at all now.
even after grounding the inverter and the computer, i get this terrible noise from the speakers that i can't even listen to anything. do you think more grounds will help? maybe 2 grounds for the inverter and like 5 for the computer? haha maybe i just need better cables or should get a ground loop isolator. damn, i'm just here typing all my thoughts
Actually, adding more grounds can reduce the noise.
It wasn't untill I actually took an oscilloscope to my pler that I noticed how much effect the strength of the ground connection can have on the noise.
Considering my player takes 4A from the battery when it is running I was able to see about 0.1V P-P noise on the ground of the player with reference to the car chassis. Compare that to the normal 1 to 2V P-P audio signal and the total audio signal is almost 10% noise!!!
Just for reference the ground lead resistance at 4A, 0.1V = 0.1/4 = 0.025ohm which is pretty low. That was using about 1.5' of 13A mains cable.
I was able to reduce this a lot by making the ground lead as short as possible, using thicker wire and improving the connections. But the noise is still there a little (white noise and alternator whine).
Ground loop isolators usually work by feeding the audio signal through a little audio isolating transformer to seperate the grounds therefore removing the ground noise. The disadvantage of this is that the isolating transformers usually cut off the audio below 100Hz pretty much killing any deap bass :-(
PS: this was with a DC-DC convter which shows that DC-DC isn't a cure all :-p
I grounded both my computer and the inverter to the same spot and I have added the ground loop isolator but I still hear a faint buzz from the speaker. is there anything else I can do??
what do you think is a good grounding point? I'm using a bolt on the seat rail(passenger side) Does anyone know??
does ne1 know?
i may have a swell idea that may help us all.
What about using the ground that the car stereo uses??? When i hooked up my stereo, there were grounded wires for me to hook up.
(I'm thinkin' maybe a Cat5 cable to the trunk dedicating 2 of the wires for the inverter+PSU ground)
I have a 95 Firebird with 2 Pioneer amps, a Pioneer head unit, and a Pioneer Cd Changer, and today I hooked up an inverter to the cig lighter, my laptop to the inverter, and the sound out to an auxillary Rca jack. I was really surprised when I heard that there was no audible noise or whine. The system sounded exactly like it did before I hooked up the inverter. It must be in the grounding.
So here is how I grounded mine. The head unit is grounded using the wire harness just like a normal installation. The two amps are grounded to the the same spot over the wheel well of the car using a really good quality and well insulated 8 gauge wire. When I grounded the amps, I drilled a small hole, and then filed the paint away to make a good contact the the car body. I then just screwed the grounds down on the exposed metal surface. This step is very important. For the main power to the amps I ran a 4 gauge line to a 30A fuseblock, and then ran 8 gauge power wires to each amp. To ground the changer I just ran the ground to one of the grounds on the amps. So far this has worked perfectly.
If you used good wire and have good contact with your grounds, you may want to check you cig. lighter; if you are using one. Who knows, it may not be grounded well. The problem may also be in the inverter itself. You may want to try a different brand or a higher quality one. If it doesn't fix the problem, just take it back.
My biggest advice would be to use high quality wire and nothing smaller than 8 gauge for power or ground if you are running amps. Also, make sure you have good contact to the car body.