Ground to Amp???

[mrToester 10+ year member]

A few checks...

(1)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. (2)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).

1) so all i need to do is take my volt meter and stick 1 side on the HU chassis and then the other ( either neg or pos) to the RCA? and i should get a reading?

2) Does this mean that i will need to connect a wire from the chassis of the HU to the output of RCA, in my case the MTX ReQ5? My two are about 5 feet from each other, do i still need to do this?

Im just a slow one when it comes to wiring, that is why i am asking this all back to you in dumb format but your reply will be greatly appreciated!

mr.toester

 

[reallyxxxxloud 10+ year member]

1) so all i need to do is take my volt meter and stick 1 side on the HU chassis and then the other ( either neg or pos) to the RCA? and i should get a reading?
2) Does this mean that i will need to connect a wire from the chassis of the HU to the output of RCA, in my case the MTX ReQ5? My two are about 5 feet from each other, do i still need to do this?

Im just a slow one when it comes to wiring, that is why i am asking this all back to you in dumb format but your reply will be greatly appreciated!

mr.toester

Your using a MTX ReQ5 so I'm guessing you have a factory H/U and are running speaker level back to the MTX. Id be looking at the MTX firstly (is the MTX chassis grounded to the car? and or by its earth wire only). Check it the same as you would the CD player with RCA outs.

I run a long wire to the batts negitive and check each devices earth for their electrical potential. All should be within .5 ohm as Keep_hope_alive had stated... Also e,g if one earth point is lower .8 of an ohm lower than the others (being the others are within spec of each) add or move earth cables untill you have closely matched desired resistance between all devices.

Oh and to the children who mocked me about "earths" - More than one earth e.g two amps, two earth cables = earths. Smartass you knew what I meant BLOODY grammer nazi's... If one earth cable is longer than the other there could be a difference in their resistance.

 

[benzmansl65amg 10+ year member]

earths are the same as grounds its old english its what the british say

 

[reallyxxxxloud 10+ year member]

Hahahahaha didn't even think of that... I'm from New Zealand but live in Australia.