system noise troubleshooting

[madhouse12]

off late people have been having so much problem with noise in their systems. what with the oh-so-professional installers who tape the power wires and rca together and then change half the system just to troubleshoot the noise, it is becoming pretty hard for the average jamil (or joe) to be satisfied without having a few very bad hair days. in this thread, i and hopefully some other experienced Pakwheelers will tell you how to troubleshoot the issue.

First of all, it is most important to find out WHERE the noise is originally originating. is it the alternator noise? is it a ground loop noise? are the rca faulty? is the pre;s ground fuse (pico fuse i think they are called) blown? are the speaker wires short somewhere? is the noise only audible on high volumes? and so on. instead of giving a lengthy detail, i am going to give short tips on how to diagnose the issue and resolve it

is it the alternator noise?
symptoms:
the sound only comes when the engine is running. it increases and decreases with the engine rpm and turning the headlights on and off.

diagnosis:
moving the rca and power wires away from each other solves the problem then its induced current noise

if turning off the engine solves it then it is alternator noise


cure:
this can be caused by the alternator or the power wires being close to the rca. for the later, simply relocate the power wires and rca as far away from each other as possible. run the power wires from one side of the car and rca from the other. for the former, make sure the alternator ground is a good one. sometimes relocating the amp ground also solves this. it can be caused by weak battery as well in some cases. make sure your power and ground wires are of same gauge and ur ground is a solid wire to body ground.

if you the rca and power wires must cross each other, make sure they do it at right angle to each other.

is it a ground loop noise?
symptoms:
the noise remains even if the engine is off.

Diagnosis:
if you are running two amps of different power and are grounding them separately

cure:
ground the amps at the same point and make sure the ground wires are same gauge as power wires. if you can not ground the amps at same point, changing the ground site of one amp might also solve it


are the rca faulty?
Symptoms:
sounds like krrr krrr. sometimes only one speaker gives this sound.

Diagnosis:
increases and decreases with volume. sound as if the music is on untuned radio. disconnecting rca one by one would end the noise.

cure:
this is an interesting fault as i have just recently seen this in a 1000 Rs. supposedly high quality rca. the wires were badly soldered to the rca plug and were touching each other. this can be solved by replacing the wires.

is the pre;s ground fuse (pico fuse i think they are called) blown?
symptoms:
.......

Diagnosis:
......

Cure:
wrapping a wire around ur pre's rca sockets and soldering it to the pre's chassis should solve this problem

are the speaker wires short somewhere?
symptoms:
krr krr noise. one speaker sounding louder than other

Diagnosis:
disconnect the speaker wires from the amp. take a 1.5 volt pencil cell and connect the speaker wire to the cell's terminal for 2-3 secs. if the cell starts to heat up, wires are short. also notice the cone movement. if one cone moves more than the other, same problem

Cure:
replace the faulty wire

is the noise only audible on high volumes?
symptoms:
the noise only comes on high volume

diagnosis:
your pre's max volume is 40 (for example only) yet you can only take it to 12 (for example only) and the loudness becomes max. and when no song is playing, u hear a hissing sound as if radio is on at low volume but not tuned to any channel

Cure:
amp gains are set too high. adjust the gains as explained in my other thread.

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this is by no means a complete solution. there are noises produced by other factors. the solutions are also not complete. its just a small effort to point out the main faults and their cures. diagnostic steps should start from the pre and follow the audio signal from there i.e.

pre>rca>amp>speaker wires> power wires.

this again is not a rule but it simplifies diagnosis. oh by the way, if the noise is coming from engine and not speakers then its an engine problem.

happy diagnosing

[DrSmiley]

Nice thread sir keep it up

[Sharo53]

:s now i think i have all the problems except alternator noice and speaker wires short..

[versatilegenious]

nice thread. SOld my ride so no noise from now

[madhouse12]

@sharo
yara start form one place and troubleshoot one by one..