Ground to Amp???

[All_Logix 10+ year member]

So I have had a few people mention to me that I might can help my alt whine if I run a wire from the chassis of my HU to the chassis on the amplifier...I am wondering if this will work because I have the pwr and RCA on opposite ends of the car, I have the HU grounded to the car chassis, and I have good grounds for the amps and still have whine, even tried different HU...if I plug ipod into amp through the RCA it goes away and if the RCAs aren't plugged into the amp there is no whine...

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[sacsking916 5,000+ posts]

Have you tried different RCAs?

 

[keep_hope_alive Premium Member]

depends on where the grounds are on the vehicle and if that is the same piece of metal. each car is different, you want to determine what is the lowest resistance path between grounds.

 

[reallyxxxxloud 10+ year member]

You have whats basically a "ground loop" this caused by the difference in electrical potential at different grounding points in your audio system. (All the grounds in a system should ideally be at "0" potential.) A ground loop typically adds a loud low-frequency hum or buzz as soon as you plug in any of various audio components, including Amp/amps, EQ's, H/U, Stackers etc. The buzz/hum is a byproduct of the multiple power supplys, power cables and a ground voltage differential within your system and its network of interconnecting cables.

A few checks...

Make sure the amplifiers have a good audio ground reference. In order for the amps to function properly, the audio ground must be referenced to chassis ground at the source unit. If it is not, the amplifier could oscillate. To check for a good ground reference, take a volt-ohm meter (VOM) and measure the resistance between the chassis of the radio and the shield of the RCA line level outputs of the radio. This reading should indicate a direct short. If this is not the case, grounding the shield of the RCA line level outputs to the chassis of the radio will probably be necessary. Keep amplifier power ground wires as short as possible. The longer a wire, the more resistance it has. When a current flows through a resistance, a voltage drop is produced. Because of this, the ground reference at the amplifier's circuit board is no longer the same as that at the chassis of the vehicle. This ground potential differential can lead to noise and improper operation of the amp. This is the same between amps and other stereo components. All should be nearly the same resistance back to the negitive terminal (yes I know - not easy to obtain).

 

[Imtjnotu 5,000+ posts]

What headunit?

Are ur rcas running along ur powerwire?....

Have you tried grounding the rcas to the headunit?

 

[All_Logix 10+ year member]

Yeah I know it's a groundloop... and I have run the RCA away from power...and it a Kenwood bt948hd, the only thing I haven't tried is what I stated above running a wire to the chassis on each and I haven't wrapped bare wire around the RCA terminals on the HU... It's kind of a stranage GL because I can put my gains down and it is still decently loud and it goes away...but I don't believe it's the full potential of the amp...has anyone else had to wrap wire around RCA terminals to ground them on Kenwoods?

 

[grandam888 10+ year member]

in would try wrapping bare wire around the rca'son the radio and grounding that to the chassis of the radio. also running a separate ground for the head unit to the chassis and not grounding it to the harness anymore.

i had this same issue just yesterday, it was so bad even when i turned my key off, my sub would thump really loud. did the above, and its completely perfect now.

also where are you located in Texas?

 

[Sub Woofin 10+ year member]

alternator whine? add some wd40 to the serpentine belt

 

[grandam888 10+ year member]

alternator whine? add some wd40 to the serpentine belt

yep, it really works, cannot get alternator wine when belt slips so bad the pulley doesn't spin.

 

[All_Logix 10+ year member]

Wow... haha, Ill give that a try grandam...its a little town called Texarkana..what type of HU did you have to do this on?

 

[grandam888 10+ year member]

i did this on my pioneer(notorious for this problem).

 

[keep_hope_alive Premium Member]

Kenwood doesn't have the same situation as Pioneer. i would just measure continuity between the RCA shield and HU chassis before i started grounding outputs. Applying a fix for Pioneer on other makes could result in damage.

simply use your DMM to measure resistance between RCA shields and chassis. if you get less than .5 ohms, then no need to wrap wire around the shield. measure before action. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[reallyxxxxloud 10+ year member]

CivicGti did you even read what I wrote?... Also check the resistance from the amps earths and from the CD player's earth to the negitive terminal. Having good earths does not mean you dont have a ground loop.

 

[jtomsic 5,000+ posts]

CivicGti did you even read what I wrote?... Also check the resistance from the amps earths and from the CD player's earth to the negitive terminal. Having good earths does not mean you dont have a ground loop.

what do you mean by "earths" ..thats a first for me on this term

 

[Kangaroux 5,000+ posts]

what do you mean by "earths" ..thats a first for me on this term

the earth is an effective grounding point if you drive a metal stake in the ground, but idk why he calls it earths since we are talking about cars..