stauren1203

iTrader: (1)

Here is the rundown... I have a Kenwood KDC BT952HD receiver with Alpine Type R speakers in the doors and a 10" Alpine Type R sub. All speakers (only 3) are being run through an Alpine 4 channel amp. Power is 4AWG cable and ground is 8AWG I think. I only have the gains up about 30% on the amp for the door speakers and subwoofer. All connections were made the high quality wire connectors. Ground WAS under one of the bolts holding the Bose wave in place, but it broke off so now I cleared the paint off of the trunk tub and tapped down with 3 screws (not ideal, I know, but I was in a pinch and the problem occurred with both grounding points.

As the title says, I have a terrible amp whine coming through the door speakers, but not the subwoofer. I installed a capacitor, but that didn't make a difference at all. What are the next things to check?

rlee429

iTrader: (25)

I remember a buddy of mine had that same issue, sounded like a turbo spooling....

1. Ended up being either a bad ground, actually a lot of devices were grounded at the same point (we ended moving the grounds somewhere else.
2. Wired the all the speakers down the center of the car and branched it out that way versus running them near the door sill.

Try changing your ground location again.

NoMoregoodUsernames

Is that what crossovers are for?

rlee429

iTrader: (25)

Don't think so. You don't have everything grounded in one section do you?

stauren1203

iTrader: (1)

headunit is grounded behind dash. Amp and Capacitor are both grounded in the same place. Where would you suggest I ground the capacitor?

gflex

Are you using shielded RCA leads from your head unit to your amp?

stauren1203

iTrader: (1)

yes

fc323

a capacitor actually does nothing to smooth signals in DC voltage..wasted money unless you have alot of speakers..
change your ground to the battery post itself if you cant find a solution or better ground

DC5Daniel

iTrader: (10)

I can't believe no one has pointed out the first glaring problem, you're running an insufficient ground. If you're amplifier actually draws enough current to require the use of 4g power, you also need to run a 4g ground. In this application just as much current is flowing through that ground as is the power feed. The tub, as you know, is not a good ground. Also, did you follow best practices while running your RCAs such as running them on the opposite side of the car as your power and routing them 6-8" away from factory wiring looms as much as possible? How did you mount the amp? A lot of cheaper/older amps will ground loop heavily if their mounting feet are metal and are screwed to the chassis. Simply unmount the amp after correcting the above issues and see what happens. Finally, when was the last time your battery was replaced? Your battery electrically acts as a filter, smoothing out residual AC ripple from the alternator's rectification. Over time, your battery loses it's ability to do this effectively and you will get whine.

I'm a professional mobile electronics installer and also an electrical engineering student, so I would know just a thing or two about this

stauren1203

iTrader: (1)

My setup isn't drawing anywhere near enough power to require 4g cables. That is just what the Tsunami kit came with. It also came with different sized power and ground cables. Is it okay to have different sized power and ground if the draw isn't enough for the size of the power to be necessary? (I hope that made sense)

I did follow all routing practices to a T. Power is on the driver's side, RCAs and speaker wire are on the passenger side. Both away from main wire harnesses.

Amp is mounted to the box. No chance of ground loop in that way.

Battery is just over a year old. It should be fine. Do you agree with fc323 that if I ground directly to the battery, assuming everything else I said here is correct, it should solve my problem?

DC5Daniel

iTrader: (10)

Running the ground all the way back to the battery is impractical and doubles your chances of the issues above. There's a reason why nearly every component in the car grounds through the chassis, it's the return path and it is a sufficient ground. Obviously small components such as lights, relays, etc. have different current requirements than an amplifier, so they can get away with grounding to relatively poor locations. You just need to locate a thick ground point which is most directly secured to the frame. You can verify the quality of your ground by doing a resistance test between the negative battery terminal and the ground location in question or a voltage drop test by metering between the positive terminal and your ground. Anything more than 1/10th of an ohm and I'd continue searching for a more sufficient location; likewise, if you do the voltage drop test you want to measure the exact same voltage as battery terminal voltage.

At this point you seem to have cleared up most of the grey area surrounding this mystery, the next options I would try:
-Switch equipment out to verify it's not the amp or head unit causing the ground loop. I'm sure you have a friend with an amp and head unit you can swap in to try. It would not be the first time I've had equipment be the source (ex: Google Pioneer pico fuse ).
-Acquire spare RCAs and simply plug them in to the deck and the amp to test. This eliminates possibility of inducted noise being picking up somewhere along your install. If the loop goes away, your RCAs need to be reran or you need to acquire some better quality and better shielded RCAs.
-End all be all solution you could try a ground loop isolator. They are a compromise, but if you're running ho-hum equipment then you'd probably never notice.