Been an electronics and audio guy for about 15 years but this problem has me stumped so I thought I'd reach out to you all for some ideas.

I have a 2004 Infiniti G35 that is pre-bluetooth connectivity and I wanted to get it to have at the very least bluetooth streaming music from my iphone. What I did was buy a cassette adapter and then connect the 3.5mm cable coming out of the cassette adapter into a bluetooth adapter, which would connect the my phone. It was all working fine but I took my car to get some minor electronics issues fixed and the tech suggested that i have an RCA soldered directly onto the back of the PCB for the stereo so that it would be a cleaner sound. I said fine, cause it was only like $20 extra.

Anyway, I get the car back and when I plug my phone directly into the cable they soldered for me it works great. Sounds awesome. now here is the kicker... when i plug that cable into my bluetooth adapter and try to play music through the phone it sounds all garbled. When i take the bluetooth adapter and use it with another stereo system (like my home stereo) it works fine. I can't figure out what to do...

I thought it may be an issue with the 3.5mm jack not connecting with the inside of the bluetooth adapter so I got an extension cord to see if it was the connection. Same garbled sound. I am out of ideas.

any thoughts?

 

Might be the strength of the signal that the bluetooth adapter sends.
The tape adapter was kicking the signal to whatever level was expected from the magnetic read head, which in turn sent it through the radio at the expected levels, so it worked fine, since everything was within tolerances.

Say for sake of argument (definitely not correct) it's doing a 2v signal from the magnetic head to the radio circuitry, while the bluetooth adapter could be bypassing that and only putting out a 1v signal, (or a 4v signal... who knows?). If your phone is putting out a 2v signal, it's fine feeding directly into the RCA, which sends the signal along the same radio circuitry as the magnetic head sent its signal, while the 1v signal is not high enough, or 4v too high.

As for the other devices you're using it with, you're connecting to a port that's made for input of various levels, rather than a fairly narrow level, like that that would come from the magnetic tape reader head.

A quick check with a 3.5mm male connector and a decent multimeter would let you check the strength of the signal directly from the phone vs. what the bluetooth adapter puts out. Not knowing those levels, this is all really just speculation.