forget what you heard----- as these poeple seem t be just passing on things they heard------- over and over againOriginally posted by Steven Another thing chris..
what causes alternator whine. Everyone has always told me a bad ground will cause it. But you seem to think that grounds don't do anything allow a return path for the current.
I've heard bad grounds can cause:
1. alternator whine
2. noise (buzzing or hissing)
3. amplifiers to go into protect mode
lets start by saying--------------------- the alternator makes noise ever time the car is runing it is the most noisest thing in the car --------this noise travels all over the chassis and through accesories-------- it has 2 parts the 3000HZ diode chopping and the lower field current
the problem here is that to the poeple who do know ------- it seems that the ground in causing the problem when it really is the bad design of the processor or amp.
let me explain------- when you want to design say a 12v processor or car audio you would want to design it such that---------- no matter what is going on in the power supply ------- noise/ buzzing/ changing states of the ground -------- that NONE of this can get into the audio circuits. The way it is done is by having very high AC-DC impedance[resistance] between the power supply and the audio circuits. As you now high impedance means that it is extremly hard for a current to pass through.
the term of this is called AC-DC power supply isolation and should be i the MEGA ohm range..... Mega ohms are seen as open circuits.
Lets take the case of something everone has heard--------- ground loops------- :
BUT before we go there lets get some things strait------ the only signal ground in the whole system should be the HU----- it ref it to the car's chassis through the ground wire/case/antenna ground and should be 0 ohms----- though ref to a noisy chassis is the worse thing you would want to do---------- but thats what these companies make us do-------- whole different story
current AWAYS wants to find the path of least resistance
well we know that the signal ground is 0 ohms through the HU and RCAs
If an amp/ or anything with low isolation is grounded near a highcurrent path on the car body some of that current will want to path THROUGH the audio circuits and jump on the RCAs to the front of the car and exit the HU. As you can guess ANY current in the signal path will CHANGE the signal
so i ask you----- if you played with your grounds getting the noise to change would you think it was the ground? yea I would too---- and I used too also---- BUT it's NOT it is the bad design letting noise in.
--------To fix it you would need either ground loop isolators------blocks the DC current down the RCAs
------OR put the whole thing on a DC-DC power supply that is high isolation
------ or just happen to find the right ground were not current wants to go though the signal wires-----------very hard----------- this step is were you here people tell others to ground all there stuff to the same point..... trying to eliminate the voltage difference between the audio gear
problems with that--------------------------------------------------
1------- this means ALL grounds would have to be at the same point amps/processors/Hu/ hu case/antenna ground/
2------- even so there are complicated issues on the high current travel through 1 point------ basicly it would still try each path equally------= noise
I've seen tests were guys put resistors on the ground and noise noise ever happens----------with high isolationWithout a good amplifier ground the connection is weak and introduces a resistance into the amps power system. As EVERYONE knows resistance = Voltage drop = Loss in amplifier power. This resistance can fluctuate with vibration. A fluctuating resistance will cause the voltage at the amplifier to fluctuate which can introduce alot of noise into the system.
alternators are normally grounded through the case-------if it isn't you are correct---------A weak alternator ground will cause the charging system to be substantially weakened. The Alternator has to work harder to maintain charging voltage and will have a premature death.
correct again --------though this has nothing to do with noise and you should understand thatA weak battery ground - well lets just say this is bad, very bad. It causes slow cranking, more boost starts needed, and our favorite enemy, a voltage drop.
but do you see why playing with your ground for a noise problem--------------------- is ---- funny?Well obviously we don't want any of these, so we tend to make sure all of our grounds are clean, tight, and reliable. ]