question about power and audio

[NeX]

hi all,

as we all know you should not run your low level audio leads parallel with your power cables, but why is it ok to run the audio cables right next to the body of the car which is earth and not ok to run it next to your 12v+ supply?

 

[NeX]

nobody?

 

[pjg1979]

Beats me, it might open a parallel universe and you and your micra will be gone for ever.

 

[richj]

well like you said the body is earthed to the battery, the same earth the head unit / amp is/should be using. The body of the car is also a sort of Faraday cage, so external interference will be minimized. If you want, cover the rca leads in a copper sheaf grounded both ends. Then they would be protected from interference from the ignition etc & could run next to the power leads. Interference is the answer to your question. Flowing current creates a magnetic field, which can cause interference due to induction in the rca cables (like an aerial). The resistance in the body, due to mass & composition is minimal, thus very little if any interference is broadcast.

 

[NeX]

Beats me, it might open a parallel universe and you and your micra will be gone for ever.

oh no! i don't want that!

well like you said the body is earthed to the battery, the same earth the head unit / amp is/should be using. The body of the car is also a sort of Faraday cage, so external interference will be minimized. If you want, cover the rca leads in a copper sheaf grounded both ends. Then they would be protected from interference from the ignition etc & could run next to the power leads. Interference is the answer to your question. Flowing current creates a magnetic field, which can cause interference due to induction in the rca cables (like an aerial). The resistance in the body, due to mass & composition is minimal, thus very little if any interference is broadcast.

yep sounds logical thanks

 

[Ed]

If you had high quality wires for audio or balanced (pioneer use balanced audio on their ip bus but its not common on car audio really) there will be no problems. Its just good practice. I ran my power with audio no problems at all and easily had 80-100db s/n.

I wouldn't worry to much to be honest.

 

[richj]

I wouldn't worry either, but that wasnt the question.

 

[Ed]

I didn't need to give a full answer - you had already done so!...

 

[NeX]

If you had high quality wires for audio or balanced (pioneer use balanced audio on their ip bus but its not common on car audio really) there will be no problems. Its just good practice. I ran my power with audio no problems at all and easily had 80-100db s/n.

I wouldn't worry to much to be honest.

wow they used a balanced audio? that is impressive, i have recently been doing stuff with that at work and its all so expensive lol

thats cool, i wasn't really worried, just wondering why people keep the wires away from the 12V+ when its right next to the ground anyway....

i am going to run the audio down the middle anyway as its a shorter route.