Keeping voice on factory nav. with aftermarket radio? Possible?

[rpm240sx]

I bought a double din head unit about 597 years ago haha that I need to install. I have just about everything ready to go. Just curious my car has the factory nav. will I lose the nav voice when I install the new head unit? If so does anyone know how to keep it. I've searched around and have found no solid info. on this topic. I've even checked with kptech. Any and all help would be greatly appreciated.

[JeromeS13]

You'll lose it.

[pfarmer]

I bought a double din head unit about 597 years ago haha that I need to install. I have just about everything ready to go. Just curious my car has the factory nav. will I lose the nav voice when I install the new head unit? If so does anyone know how to keep it. I've searched around and have found no solid info. on this topic. I've even checked with kptech. Any and all help would be greatly appreciated.

There are a couple of ways of keeping it. One is to keep the stock audio unit in place and use depending on the new head unit use a differential amp to bring the sound into the new head unit.

Another method is to remove the stock audio unit and use a differential amp directly on the outputs from the nav unit.

Pin outs on an 05 (don't have an 04 doc) indicate that the voice out of the Nav unit is on pin #7 (Voice plus) and pin #8 (Voice negative). Note that these appears to be a balanced output so you need to bring in the signal with something on the order of a differential amp. The voice signal is positive 1 volt to negative 1 volt. The 2004 is probably similar.

Perry

[rpm240sx]

Thanks, just seems like there would be an easy way for this to be done. Wonder if the dealer would be of any assistance. My local Nissan dealer has some pretty cool techs. maybe they might have some dirt on the issue...

[pfarmer]

Thanks, just seems like there would be an easy way for this to be done. Wonder if the dealer would be of any assistance. My local Nissan dealer has some pretty cool techs. maybe they might have some dirt on the issue...

My experience is not so good when it comes to anyone understanding these types of outputs and how to bring them in. Most of the audio guys I have seen seem to think it is perfectly ok to simply connect the negative to ground which depending on the other end may just have done some damage (which I suspect are some of the issues with stock head units).

This part really is not all that complicated as long as the sound is somehow not encoded which is not evident from the FSMs. In some ways this is very similar to elimination of hum on home audio equipment connected to different ac outlets and circuits. There is a difference in ground in these cases which induces the hum when you connect them together.

In this case you have a differential amplifier, often in the form of opto-isolators, which amplify the difference between the plus and minus connectors. The amplified output which is usually something like a 1 to 1 ratio (often used for mono headphones with multiple inputs). The output would then be in the form of a plus and a ground for using RCA types of inputs on the aftermarket amp.

This is also what is typically done for connecting an aftermarket amp input to the high level speaker outputs of the original amp. In this case it may be simpler since you are dealing with a single channel instead of all four.

Perry