Using MP3 Player off Cigarette Lighter Noise - VT

[dfp]

I have a VT commodore, and was wanting to use an MP3 player (Iriver) direct to the head unit line in, which is on the front of the standard unit in the car. It works well if the Iriver is playing off battery but i've tried to power it from the cigarette lighter port, and you can hear engine noise badly in the sound whilst its power off the car. Any ideas around this, like some sort of noise filter for power coming from the cigarette lighter port?

 

[semi]

try changing the earths and possibly even the power line of the cig. lighter. Often engine noise is caused by poor earths.

 

[Phreddy]

I've heard a lot of complaints along the same lines.....

It seems the power from that socket is inherently noisy - probably doesn't matter too much if you're charging your mobile phone or running a spotlight, but not so great for audio methinks.... :whistling


EDIT: If you're serious about it, I guess you could get one of those power line noise filters (they sell 'em at Dick Smith, Jaycar, etc...) and bury that inside the center console, break the wiring to the socket, and throw the filter in-line. Should work...

 

[SweetWagon]

My brother's vt done this too. It sounded like a supercharger whine! my best bet would be one of those filters also, i dont think earthing has much to do with it.

 

[dfp]

Cheers

Also seen this product at Jaycar:
https://secure4.vivid-design.com.au...&pageNumber=&priceMin=&priceMax=&SUBCATID=563
Not sure if this will do anything to help

Also the suppressor below would so if this wired behind the Cigarette Lighter?:
https://secure4.vivid-design.com.au...&pageNumber=&priceMin=&priceMax=&SUBCATID=563

 

[garfa]

My brother's vt done this too. It sounded like a supercharger whine! my best bet would be one of those filters also, i dont think earthing has much to do with it.

yup thats called alternator whine! also grounding can have everything to do with it! it could be a ground loop between the amp/s and h/u.

 

[SweetWagon]

yup thats called alternator whine! also grounding can have everything to do with it! it could be a ground loop between the amp/s and h/u.

Im aware that it was alternator whine, could have fooled me for a supercharger though I'm not going to argue about the ground loop as i have no idea, in my understanding wouldnt it be caused, in this case via interference from the power from the ciggy lighter and low-level signals in the mp3 player? like how amplifier power cables interfere with low-level RCA's if placed next to each other? I dont know how the alternator whine filter's work but it should do the job.

 

[semi]

I doubt it. The power that is running through the cigarette lighter would be pretty uniform, as in a (relatively) constant current. Interference is only caused by changing currents

 

[SweetWagon]

how is properties of the power, say taken directly from the battery different from the ciggy lighter??

 

[garfa]

how is properties of the power, say taken directly from the battery different from the ciggy lighter??

a ground loop is just a difference in potentional between 2 points. eg there is resistance between 2 gorund points. so the only way to illeminate this is to have all share a common ground (the same point). since its not exactly not very practical ot have this happen, usually we just need to find the best place for a ground. the way i would do this is to set my multi meter to resistance and then have a long neg lead and have that on the battery's neg terminal and then just scratch off the paint at various places and test their resistance.
this is becaeuse even if your ground point is great, the panel its grounded to can have crap spot welds or what ever and lead to higher resistance (the ground loop's noise gets louder as the potentional between (resistance) grounds increases.)
so pretty much yes there can be a great deal between one point of power and another.