Here we go…
Several years ago, I bought a “hideaway” stereo system. It’s a SecretAudio system made by Custom Autosound. The system consists of the main unit mounted behind the dash out of view, a small screen that hangs under the dash, and a 6 cd changer which I have mounted under the driver seat. Four new Alpine speakers in the stock locations and new speaker wires.
Ever since this was installed, I could hear a whine that followed the rpm of the engine (somewhat like what you can hear on AM stations sometimes, except this was all the time either on FM or while playing a cd) I went back to the place that installed the stereo with the problem and they sold me a noise filter to install on the power wire going into the stereo. While installing it I noticed that the stereo already had it’s own noise filter, but I installed the extra one anyway… it made no difference. The “whine” was noticeable, but also tolerable, so I just let it go for all this time.
Recently I bought a Sirius satellite radio system:
http://www.radioshack.com/product/index ... age=family (on sale for $79 plus I had a $25 gift certificate
) it just plugs in the cigarette lighter and broadcasts on a certain frequency, so you can tune your radio to that channel and hear it. I bought an extra antenna, so I can use it in my car or my truck easily. It sounds great in my truck, but in my car the same engine RPM whine I’ve heard for years has shown up about 5X louder than before. I can listen to the regular radio or a cd fine with minimal interference, but when I turn that Sirius unit on, my “audible tachometer” gets in the way so bad I can barely stand it.
I’ve read that this noise can be caused by a bad ground…. (here’s the kicker) I crawled under my dash and disconnected the ground wire that goes to the main stereo unit under the dash. My intentions were to run a ground wire straight from the main stereo unit to the battery to see if it sounded any different than using the stock ground under the dash. Just for the heck of it I turned the ignition on, not expecting the stereo to turn on… but it did
. Now I’m by no means a stereo or electronics expert, but how it can work with no ground baffles me.
I’m kind of dumfounded as to why the stereo can work at all with the ground wire disconnected. It’s the only black wire coming out of the unit, and it’s labeled GND so I’m reasonably sure that it is in fact the ground.
It also occurred to me that the case may be grounded by where it is mounted under the dash, I completely disconnected it and set it on a rubber floor mat… still worked. Just for kicks, I ran the ground wire to the battery, but it made no difference in the sound.
In order to reduce the much louder whine I hear while using the Sirius unit, I thought I might try installing my extra noise filter I have on the cigarette lighter power wires, but it seems as though I have some other underlying problem here. I’ve heard people say that this “whine” is produced by the alternator, is that true? If so, would a more modern alternator be designed not to produce this interference?
Thanks in advance for any info