| Go back to previous topic | | Forum name | Audio, Alarms, AV | | Topic subject | need help grounding my amp | | Topic URL | https://forums.2gnt.com/dcboard.php?az=show_topic&forum=i10&topic_id=3607 |
3607, need help grounding my amp Posted by rfpunch, Aug-14-02 06:39 PM
well i hooked everything up tonight and i cant get all of the ground noise to go away. i tried the seat bolts and the seat bolt. i used a ring terminal at first, then i took it off and just tried the bare wire. its making a constant thump when the radio is on. i got rid of almost all of the noise at one point but i still wasnt happy with it. i also had to run speaker level input to an adaptor because im using the factory cd player. could this be causing noise too? thanks
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3608, RE: need help grounding my amp Posted by a_miller_76, Aug-14-02 11:28 PM
Most likely you're getting the noise from that adapter. Also, where did you get your remote wire from? If you don't get it from the switched power on the back of the radio you may get that thump when it comes on. Also did you run your power wire along with your rca's? If you did this then there is a great possibility as well. There are sooooooo many factors as to what would cause your noise problem it's almost impossible to pinpoint it without knowing what all you did and what kind of materials you used. Tell me about your RCA's (what kind, how much shielding), power wire (what kind, how big), ground wire (what size, how big), who makes your rca adaptor...things like that. Also, did you check to make sure you re-grounded your radio? Our radios don't ground through the harness...only to the body. The factory grounds to the brackets which screw back into the car. If you don't have that hooked up you'll get noise. I got noise through my freakin head unit from that and I've NEVER got noise in a head unit without an amp...kinda weird.
Anyhow, I'll be willing to help in any way I can...just gimme a list :thumbsup
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3609, RE: need help grounding my amp Posted by rfpunch, Aug-15-02 12:38 AM
well lets see. the power wire is ran down the left side of the car. its 4 gauge rockford fosgate wire which goes into a power block with a piece of 8 gauge wire going to the amp. since im using the factory deck, i had to tap into the left rear +,- right rear +,- wires in the factory harness. i ran like some 20 gauge wire for each of those to the adaptor which converts that to RCAs. the ground wire is 8 gauge. the remote wire is like 20 gauge too coming from the switched power in the factory wires. the high level converter has its own ground. the guy at the stereo shop said dont ground that unless you get noise. ive tried grounding that one as well to the same spot as the amp ground. no luck
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3610, RE: need help grounding my amp Posted by a_miller_76, Aug-15-02 01:02 AM
Okay, there's a couple of things I noticed. First of all, which side did you run the wire down for the adaptor? You shouldn't have "ran" it at all. Those adaptors are designed to be hooked up directly behind the head unit then RCA cables ran for the length of the car. I would suggest doing this then getting at least a double shielded RCA cable to run...I usually go with triple shielded and braided ground cables, but I'm a lunatic :) If this is financially not to your liking you should be running a lot higher than 20ga wire....I don't do anything that isn't 12ga at least, and if you're running wire to the back to give signal to a line converter it should be 12ga with seriously thick insulation. This will keep what's called "ground loop" from happening. Ground loop is when the negative charge that's grounded into your body jumps through the insulation on your signal cable and returns back to the amplifier. Once again, get rca's and put that adaptor behind the radio. Run the RCA's on the opposite side of the car from your power cable. Rockford power cable is good stuff so I wouldn't worry about that at all.
Also, what kind of amp are you using...I would guess by your name you're using Rockford, but you never know. If so your amp should have protection circuitry to keep these things from happening...so if you're getting noise from your amp the problem is actually very serious because the amp will cancel out all it can, if something's getting through that means there's more noise going into the amp than it can handle. Also, you have to have some kind of RCA's going from that adaptor to the amp. Make sure they aren't unidirectional. The should have little arrows on the side of the wire if they are. Make sure the arrows are facing the amp. I turned around a set of RCAs once and I couldn't believe the difference.
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3611, RE: need help grounding my amp Posted by SPL_Eclipse, Aug-16-02 02:44 PM
what exactly does the noise sound like? is it a constant hum, or does it rise in frequency as the rpms go up? or is it just static?
because you mention a turn-on "pop", im guessing theres a bad ground somewhere, probably the headunit (because you said you grounded the adapter). perhaps the adapter is defective?
to start troubleshooting, your best bet is to move your way back upstream in the audio path. start by disconnecting the RCAs from the amp. turn on the system. if you hear any noise, you know the problem is in the amp. plug the RCAs back into the amp, and disconnect the speaker inputs on the adapter. turn it back on and check again. if youve got noise, you know its the adapter. if you dont, its probably the headunit. this isnt foolproof, but works most of the time.
as mentioned above, you could have a ground loop, however it is caused by multiple grounding paths for a single device. on most amplifiers (and other audio devices, like the adapter), the RCA shield is not seperated from the 12v- ground. when the device is not grounded properly, it "seeks" out a new ground: your RCAs. current then flows backwards (or forwards, depending on the path of least resistance) into the RCA input of another device in the stream, and then is grounded out to the chassis. this is not only VERY bad for the electronics in the system, but also results in lots of noise, typically a constant hum or a distorted type of sound.
there might also be gain adgustment knobs on the adapter. make sure these are set correctly, because if they are set too low, you are probably compensating by raising the headunits volume and sending a clipped signal on to the amp.
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