Expert: Peter G. Lee - 8/13/2006

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I would like to know how to wire a car stereo to a headphone jack and have it play in stereo instead of mono. I tried wiring front left+ and right+ to jack and combined front left- and right-to ground on jack which does not work. This causes the headphones to heat up fast! So when I remove one of the negetives it works but not in stereo.
The stereo is installed in a tractor and because of the noisey enviroment I wear foam ear plugs then put on headphones which works well. The radio is a sony with 30 watts. There are two rear speakers that are hooked up to this radio they are small and it's to loud inside the cab to hear them anyway, so I was trying to use the front radio speaker wires to wire a headphone jack and ran into problems. To answer your question this is a four speaker radio/CD player hooked to two rear speakers and the front hooked to a (MONO) headphone jack. Thanks for response.

Answer -
Sorry I need more info.
Are you trying to install a headphone jack for passenger (front or rear?) use or for the driver use (illegal) instead of the speakers or as well as the speakers? Are you working on a two speaker (front only) radio without rears or a four speaker radio and not connecting the rears?
Let me know and I have diagrames I can e-mail you to do it with a switch or relays.
Peter

Answer -
OK MARLIN! Oh your out of the tractor, :-)
If I read it right the phone set up you have is wrong, many radios have a common earth on all speakers, yours, it seems, doesn't, you need to buy a socket and jack with 4 bands on not three, this will have 8 connections on the socket if switchable and 4 if a plain socket, 4 input, (L&R+ and L&R-) which can output to the two front speakers when the jack is out and give stereo to headphones when in.
Search ebay for "4 pole" and you wil find a few listed
Peter

Thanks Pete, but I would like to use a standard 3 pole jack for the headphones. I have already wired a pair of headphones with an extra ground wire "4 wires" but what a pain. I have read in other forms where they have said you could wire a 300ohm .5watt resister on the positive leads and not wire the negitive leads to anything. The ground is a common ground through the frame? Have you heard of this? I was hoping this would be a simple problem. How about aircraft, motorcyles and noisy machines surely this has to be a simple thing to do. Marlin.

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Speakers are either 4 or 8 ohm so I couldn't reccomend 300ohm, if you have a 8 wire speaker system rather than a common earth system then you will need to run two pairs and that means 4 pole. it's not a case of what vehicle it's fitted to, it's what head unit you are running.
I have just tried it out on the bench with a Kenwood 4 x 40 set and it works fine with l & R earths joined and l & R poss the l & R speakers so it must be your head unit.
Have you tried feeding l & R from the unit but earthing the ground on the jack socket instead of going to the neg leads?