weird sound interference only when engine is on!

**canadamatt** · 05-01-2007, 06:05 PM

I have a inovatek in-car LCD screen head unit. with the engine off, everything plays great including the screen but when i turn on my engine a very annoying noise is produced out of the rear speaker. my rear speakers are amplified. this sound's frequency is directly proportional to the revolutions of my engine.

does anyone have an idea why this sound is being produced?

**WarX** · 05-01-2007, 07:09 PM

your rear speakers are amplifier? re-route the RCAs at least 18inches away from the power wire... so power wire on ONE side of the car, the RCA's on the opposite side of the car

**Dennis5587** · 05-01-2007, 07:14 PM

yeah, i got a great idea... but I really think all you need to do is

ps: search alternator wine

**WarX** · 05-01-2007, 10:33 PM

Originally Posted by Dennis5587

yeah, i got a great idea... but I really think all you need to do is

ps: search alternator wine

How is that anyways? I've never tried Alternator Wine

**XC-C30** · 05-01-2007, 10:35 PM

maybe somethink like motor-oil?

**canadamatt** · 05-02-2007, 05:22 AM

i looked up alternator wine and i disconnected my RCA cables from the amp while my engine was on. when i disconnected the cables the sound went but then when i plugged them back in it came back on. does this help anyone deduce the problem?

**RodeoTristan** · 05-02-2007, 06:37 AM

Try changing the earth of the amp to a different point. Check all connections running to and from the head unit to the amp ect because that can also cause interference.

**UV7** · 05-02-2007, 12:41 PM

What you are describing is a symptom of a ground loop. A ground loop occurs when there is a difference in potential between ground points. The most likely culprit in this case is your amplifier's ground. Ideally, all electronics would ground to the same point, thereby eliminating any possibility of a difference in potential, but this just is not possible. Since the majority of the electronics in the car ground to the frame, the best possible location to ground the amplifier is also going to directly to the frame, or as close to it as possible. Seat bolts, bracket bolts, etc., anything that will make solid, metal-to-metal contact as close to the frame as possible is going to be a good ground. You also need to ensure the ground point is clean and clear of any resistance. You will want to grind away any paint, remove any insulation, padding, dirt, carpet, etc., from the ground location so that the amplifier's ground makes as much contact as possible with as little resistance as possible.
I hope this helps.