Difference between car audio system and portable speaker

[hamzamahmood96]

I have made this post on a few other forums but i haven't found much help.

I'm an absolute noob when it comes to audio systems. I've heard terms like impedance matching and having separate grounds, but I'm unaware as how to apply these stuff, anyways here it goes:

I designed a circuit which would turn on LEDs with intensity of the music (music reactive LEDs). I tested this using a portable Chinese speaker and it worked amazing. This makes me think that the circuit design I used for this is not @ fault for what I'm about to mention, anyways the circuit is attached (RGB.jpg).

I take the 12V from the car battery. The J1 connector is where i hook up the audio connection(Left or Right and ground). Now as i need 2 AUX wires, one for this setup and the other for the audio system itself, i make use of an AUX splitter, pic attached (IMG_20190804_015229.jpg).

The male part of this goes into my phone, two AUX cables are plugged into the female end, one going to the audio output, while the other goes to my circuit.

Now the problem: When I plug this whole setup in the car, and plug the AUX into the car stereo system (KENWOOD) the LEDs do not work the way they should, for example they do no catch the beat of the music. Or the LEDs would stay lit even if there is no music playing. However if i just take out the AUX from the car stereo system (KENWOOD) and plug it into a portable speaker(keeping the rest of the setup same), the LEDs work flawlessly.

For some debugging :
I checked the connection of the ground coming from the AUX input with the ground of the car(battery) using a digital multi meter. It did NOT show a short circuit, which might mean it has a floating ground ?

If it helps you in helping me, the unit installed is Kenwood KDC W3044 (https://kasc.kenwood.com/files/prod/1163/5/KDC-W3544W_W3044_W313(EN).pdf)

Please help me on how to solve this issue. I am totally clueless on this. If you find the information incomplete, I'll be happy clarify. And feel free to suggest any improvements to the circuit in question.

 

[russc]

1 - I assume you are plugging into your phone headphone jack?
This is an audio output.
2 - your car aux-in is an audio input.
3 - the 10K is putting 12v DC to the input plug which is not good.

 

[hamzamahmood96]

1 - I assume you are plugging into your phone headphone jack?
This is an audio output.
2 - your car aux-in is an audio input.
3 - the 10K is putting 12v DC to the input plug which is not good.

Thank you for replying.
1. Yes, that's right
2. Yes, that's also correct
3. I will try out the circuit without the 10K resistor there, but it working with the portable speaker makes me believe its working as expected.

In addition, I tried this setup in another car just now, whose aux-in ground seems to be shorted with the chassis of the car. The system worked flawlessly there.

The concept is that my phone gives the signal, and that splitter "splits" the signal. One wire goes to the car aux-in, the other wire goes into my circuit and does the LED stuff.

Please advise, thanks