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Head Unit Grounding Question

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=37704
Printed Date: May 04, 2024 at 8:06 PM


Topic: Head Unit Grounding Question

Posted By: TubeDriveRMD
Subject: Head Unit Grounding Question
Date Posted: August 18, 2004 at 10:37 PM

Hi guys. I recently had my system professionally installed. Cosmetically they did a great job. Unfortunately, i have an awful alternator whine.  I have only had the system running for 1 wk yet i cant stand to listen to it because of the noise!!! aaaaaaggggggggghhhhh!

Anyway, i did a few tests. im certain that the ground loop is entering via the HU ground which is grounded up front through the original factory ground.  Im assuming this is through the wiring harness?? anyway ive isolated it to the HU ground because......

 1. I replaced the head unit (sony cdx c910) with new eclipse cd8443.  ground loop persists

 2. I patched my ipod into the eclipse via the AUX input.  same ground loop.

 3. i disconnected the eclipse rca output and directly patched my ipod into the line driver which takes the signal directly from the HU and sends it to the back into xover, amps over XLR cables!!!  Viola! the alternator whine disappeared.

Am i correct in believing the HU ground is the cause of the ground loop.  The remainder of the system is grounded in the back (3 amps, xover, etc).  I know install rule 101 says to ground all compnents to a SINGLE spot.  I am assuming that this includes the HU. Nevertheless, i am extremely disappointed in my installer.   1000$ install and i have alternator whine??? 

So, i rescheduled to have the installer go back and run a ground cable from the HU to the back where the ground distribution block is located. 

So what do ya'll think??    I am well aware that car audio is frought with noise but i feel they should at least ground the system properly .  Did they follow standard install technique and i am being too demanding???




Replies:

Posted By: switch_hitter
Date Posted: August 18, 2004 at 11:13 PM
you should have made the installer fix the problem right away...I would take it back. Or if you feel confident enough to tackle the job, do it yourself...and make sure its done right...

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2 Memphis HPO 12s
1 Memphis 1000D
2 Memphis 8s
1 Memphis MC200
4 Memphis 3way 6 1/2s
1 Memphis MC3004
4 Memphis Tweeters
1 Memphis 3-way electronic crossover
2 Memphis 5 1/4
2 Memphis 4s




Posted By: stevdart
Date Posted: August 18, 2004 at 11:51 PM

^^Agree with the above comment, but don't spend any more time on this.  You paid for professional results, now go back and get what you need done before you mess something up.  The more you mess with it the more likely the shop will think you caused the problem.  You should have no noise in the system when all is said and done.  Except for the music source you choose to listen to...

You said that "install rule 101 says....", but believe me there is no such rule.  Grounding is sometimes a matter of trial and error because of the differences in each car's electrical systems.  The installler obviously didn't hear the whine or it wouldn't ( or shouldn't ) have been let out of the bay.  In a case like that you turn around and go back as soon as you hear it.



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




Posted By: TubeDriveRMD
Date Posted: August 19, 2004 at 12:04 AM

i appreciate the input. just wanted to make sure that whine is totally unacceptable for a professional install.  this was performed at a very well-respected car audio dealer in a major u.s. market.  they know better.  the manager acted as though i was putting them out. whatever. they got paid. they will do the job right.

thanks again guys!



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Eclipse cd8443
Phaze LD1 line driver
Phaze LDX-23 Xover
Butler1500 TubeDriver (2)
Dynaudio 220
Boston Pro 10.4LF
Zu Cable balanced XLR cables
Kimber Kable speaker wire




Posted By: stevdart
Date Posted: August 19, 2004 at 12:20 AM
They won't keep that "well-respected" status for very much longer putting out results like that, will they?  BTW, whine is also unacceptable in a driveway install.

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




Posted By: chevyman26
Date Posted: August 19, 2004 at 12:39 AM

Hear ! Hear !

                 - The Driveway Man



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You'd better get me out of this lord... or else you'll have me to deal with. -- Hunter S. Thompson "F.A.L.I.L.V."





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