car engine rev interferance with radio

[SilverSaloon]

hi

as u may have read HERE i have just fitted a dvd player to my car that goes via comand.

the video signal and audio L and R signals are sent via phono cable to the comand.

When driving the revs of the car go thru the speakers as a high pitched whine. Could this be due to the quality of the cables i used? they were just basic phono leads - do i need shielded ones or something?

any ideas would be appreciated.

 

[Paul Grainger]

Ummmm - I have the same problem with my DVD player.

Strangely, it seems to come and go.

My DVD player is under the drivers side seat, sometimes I can reduce the noise by raising the seat slightly.

Let me know if you get a solution. My phono cables are reasonable quality, and connect directly to my TV tuner which is mounted behind the rear offside trim panel.

Paul G

 

[miro]

hi

as u may have read HERE i have just fitted a dvd player to my car that goes via comand.

the video signal and audio L and R signals are sent via phono cable to the comand.

When driving the revs of the car go thru the speakers as a high pitched whine. Could this be due to the quality of the cables i used? they were just basic phono leads - do i need shielded ones or something?

any ideas would be appreciated.

You either have a chassis ground continuity with audio ground (most likely) or you need one of those metal woven screens (like the ones used on newer cars) which are grounded on one end only.

My friend bought a Taureg and the factory MP3 player called a PHAT BOX has a gound problem where the chassis, ground and audio ground are all connected. Since my friend is a wiz kid he wont have any hassles fixing it but I am quite confident that this is a good place to start.

Unfortunately it means cracking open the DVD player to see which 1 penny part was left out and caused the leakage.

As you know ..... any wire grounded at two end is an antenna. So the antenna is working perfectly. Its picking up the noise it is naturally designed to do by the laws of physics. In effect it is the outside not the core of the cable that is causing the problem.

Either find a clever way to break that ground loop or shield the signal.

 

[miro]

I seem to recall that there are also ground loop breakers for TV signals. Only in TV it gives a herring bone pattern. Since those are RCA oriented I can only wonder if they would help.

www.channelplus.com

This American company makes one very small inline device which can help.

 

[SilverSaloon]

I seem to recall that there are also ground loop breakers for TV signals. Only in TV it gives a herring bone pattern. Since those are RCA oriented I can only wonder if they would help.

www.channelplus.com

This American company makes one very small inline device which can help.

so u reckon it has nothing to do with the cables i am using?

 

[nickmann]

You can get an inline ground loop isolator from Maplin for about £8. Or a car audio place. I don't know enough about the subject to know if it will fix your problem though, sorry.

I had the same problem with my in-car DVD. In the end it turned out to be a cheap low-quality IR audio transmitter (from TGincar). Problem not evident with higher-quality kit from Veba or Centurion. Usual story - serves me right for trying to save a few quid.

 

[SilverSaloon]

You can get an inline ground loop isolator from Maplin for about £8. Or a car audio place. I don't know enough about the subject to know if it will fix your problem though, sorry.

I had the same problem with my in-car DVD. In the end it turned out to be a cheap low-quality IR audio transmitter (from TGincar). Problem not evident with higher-quality kit from Veba or Centurion. Usual story - serves me right for trying to save a few quid.

maybe i need a noise surpressor????

 

[nickmann]

for the price its gotta be worth a try. Yours is nice and easy to get to as well so won't take long to try it.

 

[Thmsshaun]

Phono quality can be an issue here. You want a good Oxygen free cable from any car audio supplier.

Also try running the cable down a different side of the car.
Try running the cable across the centre of the car loose to see if the interference still occurs and also check there is a good connection.

Running my amps I get the whine through my front speakers sometime barely noticable even on low volumes but other times I can get a high pitch sound. This I found was just due to poor connection at the back of the headunit. Again good quality gold plated phonos instead of cheap nasty in home stuff will help.


Hope this helps

Shaun

 

[SilverSaloon]

Phono quality can be an issue here. You want a good Oxygen free cable from any car audio supplier.

Also try running the cable down a different side of the car.
Try running the cable across the centre of the car loose to see if the interference still occurs and also check there is a good connection.

Running my amps I get the whine through my front speakers sometime barely noticable even on low volumes but other times I can get a high pitch sound. This I found was just due to poor connection at the back of the headunit. Again good quality gold plated phonos instead of cheap nasty in home stuff will help.


Hope this helps

Shaun

thanks. i thing i will try the following in this order:

(1) replace the phono leads with gold-plated good ones (current ones are from a home-dvd system)

(2) try keeping the wires away from the 12v wires

(3) fit noise surpressor

(4) cry


as the dvd player is fitted under the glovebox i am limited to the route where the wires go to the comand unit.....

 

[guydewdney]

i have a similar problem - a whine directly related to engien revs...

but - i ran a second set of cables OUTSIDE the car - whine still there.

do i need to break the ground loop on the phonos? - if so - why cant i just cut the shield right next to one of the phono plugs?

 

[Will]

What happens to the whine if you apply a decent earth to the outside of the phono plug?

 

[Will]

Might be of help to some people here:

Link

Cheers

Will

 

[miro]

i have a similar problem - a whine directly related to engien revs...

but - i ran a second set of cables OUTSIDE the car - whine still there.

do i need to break the ground loop on the phonos? - if so - why cant i just cut the shield right next to one of the phono plugs?

Despite the fact that urban myth dictates you must use silver cables hand woven by tibetan schoolgirls there is only one way to break an Earth loop and that is to break it. However, breaking continuity completely just kills the audio circuit but why not try it anyway. Who knows what strange things happen in cars and no other place.

If you have a MB TV tuner then you can see the extra-ordinary lengths they have gone to in order to avoid the tuner RCA connectors touching the chassis of the tuner.

 

[guydewdney]

Despite the fact that urban myth dictates you must use silver cables hand woven by tibetan schoolgirls there is only one way to break an Earth loop and that is to break it. However, breaking continuity completely just kills the audio circuit but why not try it anyway. Who knows what strange things happen in cars and no other place.
.

ex aerospace wiring connector design engineer here.. no bloomin' fairys for me thank you..

OFC cable only gives a difference in longevity - not signal (OFC corrodes less than non ofc)

ill try a) grounding separately the sheild then b) cutting the sheild at one end

 

[Thmsshaun]

Another problem can lie with the quality of the audio equipment and what is around it.

I am running 3 amps with 3 sets of phonos running the length of the car. The noise only appears through the front speakers. I was talking to my local ICE shop and about the supressors. (Which may help but not guaranteed) And they said it could be just a poor amp. Tried a friends amp and the problem was not so persistent.

One of the many wonders of car electronics.

 

[Will]

Another problem can lie with the quality of the audio equipment and what is around it.

I am running 3 amps with 3 sets of phonos running the length of the car. The noise only appears through the front speakers. I was talking to my local ICE shop and about the supressors. (Which may help but not guaranteed) And they said it could be just a poor amp. Tried a friends amp and the problem was not so persistent.

One of the many wonders of car electronics.

Is it the front LHS speaker that is creating the most noise by any chance?

 

[Thmsshaun]

No it is both. Not even sure if its the left hand phono now its not to bad generally only me in the car so the solution is play it loud

Going to sort it out at some point replacing my 2 small amps with 1 4 channel VIBE Still with all the cash im spending at the min it will be a while yet its not at the top of the list.

The thing with the front is I am running phonos to the amp. This is in the spare wheel well (not the best place anyway) Then the crossovers for the front speakers are in the boot. so there are the 2 sets of wire each side running back down the car. one for the mids and one for the tweets.

The seperate crossovers are to the left and right of my sub amp. So as you can tell it will be a good days work to re wire and stage by stage to find the source which is why im leaving it until i get the new amp.

p.s Sorry to hijack the thread

 

[Will]

No it is both. Not even sure if its the left hand phono now its not to bad generally only me in the car so the solution is play it loud

Going to sort it out at some point replacing my 2 small amps with 1 4 channel VIBE Still with all the cash im spending at the min it will be a while yet its not at the top of the list.

The thing with the front is I am running phonos to the amp. This is in the spare wheel well (not the best place anyway) Then the crossovers for the front speakers are in the boot. so there are the 2 sets of wire each side running back down the car. one for the mids and one for the tweets.

The seperate crossovers are to the left and right of my sub amp. So as you can tell it will be a good days work to re wire and stage by stage to find the source which is why im leaving it until i get the new amp.

p.s Sorry to hijack the thread

What happens if you substitute the phonos from the rear speaker's amp with those for the front?

 

[Thmsshaun]

It is the same. I think the amps location if partly to blame. The amp for the rear speakers is in place of the first aid kit. and that is fine. (there wasnt one in there when I got the car) I did rest it over the sub amp and that seemed to help but couldnt be left like it as it looked a mess and would damage the other amp.