High Pitch Noise When Rolling Down Window

In a 1998 Mitsubishi Eclipse, power windows and door locks...

I get a high pitch constant noise [through the stereo] at a specific point when rolling down the window.

It's only at a specific point, like 3/4 of the way rolled down... at that specific point, the stereo will emit a loud high pitched noise that will remain constant... If I roll the window up a bit, the sound goes away.

What could cause this? Are there any specifics about the stereo that you need to know? I will generalize: alpine deck and digital signal processor, 3 kicker amps, one for kicker component fronts, one for kicker component rears, one for kicker sub, did have an alpine alarm, but it was removed.   

-------------
--
Brad

From what you say, it's not the actual motor movement of the window relay that causes the high pitch (my first thought) since you said these were power windows.  But if you let off the actuator with the window at a certain point, the high pitch remains.  That right?  Finger off the control, no motor, the high pitch remains...

That leads to an acoustical anomaly.   With the window at a certain height (and do both front windows do the same thing, or just the driver's?) there is an abnormal pitch associated with that height.  Can you hear that pitch from any other location within or outside the car?  Depending on further study into it on your part, it seems to me that the pitch is heard from your listening position and has to do with geometry...the plane of glass and where it abrubtly ends in relation to your ear.  Do this too:  pinch the closest ear shut and find if you can hear it also with your right ear.  The relationship of space to the window will be different and I'm guessing you might not hear it.

The sensible solution, of course, is not to leave the window at that position.  I'm guessing at this point that the position of the tweeter and its angle is the source of the problem.  If possible, and if it leads to this, try to reposition the driver's side tweeter slightly and see if this problem stops.

(PS:  I have been dead wrong from out in left field before, so...)

-------------
Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

It could also be something shorting out a speaker line partially in the door.

-------------
sparky

Thank you both for the time to post responses.

The sound is 'noise' introduced into the stereo itself.

I believe it to play this high pitch screach from all speakers, but I will have to verify this.

It does it on both windows, about 3/4 down, and you will have to move it up or down a little to get it to stop.

You can hear the sound from all areas of the car, and outside of the car. I believe the sound is in line with the volume the deck is set at... turn it up, sound is louder... I will have to verify that though.

I will have to check a few things, as this is a 'project' car I keep out at my parents house.

IF anyone has came across a similar situation, let me know what you think.

-------------
--
Brad

I would start by inspecting one of the doors. It seems that the window position is the critical factor. It may be causing something metal to short out a speaker connection.

-------------
sparky

I will examine the door's movement this weekend and report back to this thread early next week.

Thanks for the advice.

-------------
--
Brad

I havent looked at it yet, but since both doors exhibit this behavior, I would 'guess' that it is not a short.. Very very odd none the less. 

-------------
--
Brad

I think you have a wire that's touching the window frame.

-------------
Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA

i have that same problem, but when i start my car, it's get a thumb noice in my audio, but when i have the audio volume at zero i don't get it, so i know it's my RCA that is the problem somewhere it's touching something i think, haven't the chance to check it out. Super20G, have you try it at different volumes and at zero?

-------------
Shaking The Neighborhood

I will have to verify, but I belive when the deck is at level 0, there is no noise. Any other level there is this noise in the system. Sounds like RCA's will be the first thing I pay attention to when I pull the doorskins off.

-------------
--
Brad

After pulling off the doorskins, I found that the speaker wires running to the seperate tweeter were grounding to the frame due to a cut in the sheathing... I guess rolling down the window partially made the wire connect to the door frame and introduced noise into the stereo...

-------------
--
Brad