Need Help with RCA Cord Over-Amplification or Noise

 

New member
Username: Bob_k

Post Number: 2
Registered: Apr-08
I'm trying to connect an older (1995) Sony CDX-51RF 10 disc changer to a brand new Kenwood head unit in my car. The Sony changer normally uses an FM transmitter hooked to the antenna cord, and sound from the Sony disc changer is provided to the FM transmitter via left and right RCA cables. The transmitter is grounded to a console metal member. The Kenwood head unit is grounded through the OEM stereo wiring harness. I want to connect the disc changer RCA outputs directly to the Kenwood head unit so that I'll get better sound. Power and control for the disc changer would still be provided by the original CD changer control and FM transmitter/control box. In other words, nothing is changing except for where the disc changer RCA output terminals are connected.

When I plug the disc changer RCA outputs into the Kenwood head unit RCA aux. inputs, the signal is extremely distorted, as if it's being overdriven or as if the incoming signal from the CD player is too strong. The distortion occurs at any volume level. This isn't a hum or a buzz. Rather, the audio is just extremely distorted, kind of like turning the stereo all the way up on a cheap set of speaker. However, when I back the RCA connector out so that only the center plug is touching (i.e. the outer conductor is not touching & not grounding), it produces a more normal signal, albeit with a little bit of noise.

Does this indicate that the Sony disc changer has an amplifier in it and is providing too much power to the Kenwood stereo? Or, does it indicate that I have some sort of grounding problem? Do you have any suggestions or equipment for solving this problem?

How might I measure the output of the Sony disc changer on the RCA cables to determine if it is an amplified signal or if it is a standard "line out" signal that can be handled by the Kenwood head unit?

Incidentally, when I plug an MP3 player into the Kenwood head unit RCA aux. inputs, the sound is just fine, so the problem is definitely something peculiar with the signal coming from the Sony disc changer.

Thank you for your help!
 

Gold Member
Username: Kpa2727

Old Bridge, NJ USA !

Post Number: 1155
Registered: May-07
sounds like there is a amp in that system as you were saying , theres not much else that would cause this unless u were plugging into a outputon the kenwood, does the kenwood have a line in ? if so give that a try see if it accepts it any better.
 

New member
Username: Bob_k

Post Number: 3
Registered: Apr-08
Yes, the Kenwood HU has a 3.5mm aux input on the front faceplate. When I use a RCA-to-3.5mm plug adapter and plug the CD changer into the front aux input on the HU, I get the same distortion.
 

Gold Member
Username: Kpa2727

Old Bridge, NJ USA !

Post Number: 1158
Registered: May-07
no no , line in is diff from aux.
 

New member
Username: Bob_k

Post Number: 4
Registered: Apr-08
The RCA inputs on the back of the HU are line in.

The fact that I get the same distortion whether I use the rear line in jacks or the front aux. jack indicate to me that it is an inherent issue with the signal coming from the disc changer.
 

Gold Member
Username: Kpa2727

Old Bridge, NJ USA !

Post Number: 1161
Registered: May-07
hmm, to be honest if you won't loose much just ebay the unit buy new. it seems like if none of those options work your going to have to probably buy a adapter or something s miss with the unit. also being that it's a 95 and i have owned aloto of speakers and stuff from that erra. most likely theres is deffinatly a amp in there. i know even older computers the sound cards were amped cause the technology for amping a speaker internally like we do today didn't exist and due to that, now if you were to try and hook are curent erra speakers to it, you would hear the same thing you hear now with your unit.
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