GLI - Live With It???

[rbenz27 10+ year member]

Ok, I have a ground loop problem and the only solution that seems to work is to use a Ground Loop Isolator hooked up to the RCA's on the amp. I just got the system installed recently and took it to 2 different shops and they were both not able to fix it. I went to the first store where I had purchase and installed my system. After having the car for the whole day, they were unable to solve the problem without using the GLI.

I did an A/B comparison with the GLI on and off and the difference was night and day. With the GLI on, the highs was harsh and the lows were muddy at higher volume levels. With the GLI off, the sound was completely clean on the highs and lows while playing at high volume. This really kills me since I am forced to use the GLI and compromise the SQ.

The noise is classic alt whine. Its only there when the engine is on and the pitch changes when the gas pedal is pressed. The noise is very faint and one shop even went so far as to suggest its "acceptable"! I can tell its there though and it drives me nuts.

One shop I went to, we replaced the RCA's with $100 monster cables. We first ran it over the car seats and carpet and the noise is gone. When they ran the cables underneath the carpet the noise came back! So I ended up just using my existing RCA's.

The other shop where I left my car for them to work with did a lot of things that one would do to get rid of ground loops i.e. ground at amp, deck to batt. neg. grounding rca to chasis, moving deck ground to behind dash, disconnecting antenna cable, switching decks, etc. They pretty much did everything but one thing that interested me was that they said they used their highest quality RCA running over the seats and carpet and with the Deck outside of the dash and the noise was still present.

The only other thing I can think of is to do the Big 3 upgrade or 2 out of the 3 which are: Battery negative to Chasis and Engine block to Chasis. My installer said that with my system it won't help so they didn't do it.

What do you guys think? Should I just live with a compromised system? Will upgrading 2 out of the Big 3 make a difference? If there is anyone living in the 808 state that is willing to take a look at my car and help me out, I would really appreciate it.

My system is pretty simple:

2005 CR-V

Alpine 9835

Rainbow SLC 265

Stock Rears (powered by HU)

ARC 12D2 Sub

ARC 4150-XXK (powering rainbows and arc sub)

Click to read more...

 

[kuijo 10+ year member]

did you reground ur headunit and make sure everything has a common ground? your amp could be broken or your deck. maybe a bad rca ground on one of them. Id suggest finding a friend with an alpine that can you can switch with and see if its the deck and then switch amps with someone and see if its the amp. You could also try plugging the rcas into the rear preouts ( i assume you have them coming out of the front since the one amp is powering both sub and speakers.)

Do you hear the whining out of the rear speakers?

I had altenator whine and i replaced my RCA's and it went away and never came back.

 

[rbenz27 10+ year member]

did you reground ur headunit and make sure everything has a common ground? your amp could be broken or your deck. maybe a bad rca ground on one of them.
I had altenator whine and i replaced my RCA's and it went away and never came back.

Yes, they tried regrounding the HU to behind the dash. They even tried grounding to the same ground as the amp. They also tried grounding a piece of wire from the RCA shield to the HU chasis. The amp is not broken, my installer put in a new amp. The deck is not broken, I bought it brand new and we tried putting in my old deck and the noise is still there.

The 2 shops I went to tried to replace the RCA's and the noise is still there. I think I'm going out of my mind //content.invisioncic.com/y282845/emoticons/eek.gif.771b7a90cf45cabdc554ff1121c21c4a.gif

Next thing to do is the Big 3 but I don't know if it will solve a ground loop problem.

 

[kuijo 10+ year member]

What size ground and power wire is the amp running on?

Are the rcas running on the same sides as the power wire?

 

[rbenz27 10+ year member]

What size ground and power wire is the amp running on?Are the rcas running on the same sides as the power wire?

I'm not sure what size, I have to take a look at the car when it gets back here but it looks pretty beefy. The RCA's and the powere wire for the amp are running on opposite sides of the car. The noise is definitely coming in from somewhere in the HU or in front of it.

If we unplug the RCA's on the amp, the noise is gone. If we put it in the GLI on the amp the noise is gone. So this must mean that the ground loop is at the HU? But we have tried every single fix mentioned but we are still getting alt whine. //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

 

[stones 10+ year member]

This link is based on home audio but the principals are the same-

http://www.epanorama.net/documents/groundloop/index.html

Here is some extra info cut and pasted from rec.audio.car FAQ

2.1 My speakers make this high-pitched whine which matches the engine's

RPMs. What is it, and how can I get rid of it? [iDB]

==========================================================================

The answer to this section was generously provided by David Navone of

Autosound 2000. The material in these instructions was adapted from

the Autosound 2000 Troubleshooting Flow Chart by Ian Bjorhovde with the

permission of Autosound 2000. For more information about Autosound

2000, (see Section 7).

This is a set of instructions to debug a stereo installation if there

is any noise present after it is completed. Follow each step

carefully! If you have more than one amplifier, repeat level one for

each amp to be sure that none of them are responsible for the noise.

2.1.1 Level 1: Check out the Amplifier(s)

------------------------------------------

After you have determined that there is noise in the system, determine

if the amplifier is causing the noise. To do this, mute the signal at

the inputs to the amp by using shorting plugs. If there is no noise,

then the amp is fine, and you can proceed to level 2. However, if

there is noise, then use a test speaker at the amp's output. If this

stops the noise, then the problem is originating in the speaker wiring,

or the passive crossovers. Check to make sure that none of these are

shorting with the body of the car, and start again at level 1. If

noise is still present when using the test speaker, then there may be a

problem with the power supply on the amp. Try connecting an isolated

power supply - if this does not get rid of the noise, then there is

something seriously wrong with the amp, and it should be replaced. If

the noise goes away, then there may be a problem with power supply

filtering or isolation. This can be fixed by changing the amp's ground

point or b adding external supply filtering.

2.1.2 Level 2: Reduce the System

---------------------------------

The amps have been determined to be noise free. If you have any

processors between the head unit and the amps, disconnect them and

connect the head unit directly to the amp. If this gets rid of the

noise, then one (or more) of the processors must be at fault, so

proceed to level 5. Otherwise, try running the signal cables over a

number of different routes. If you are able to find one that does not

produce any noise, permanently route the cables in the same manner, and

proceed to level 5. If not, then you must isolate the head unit from

the car's chassis (except for its ground!) - don't forget to disconnect

the antenna, since it is also grounded to the car. If isolating

the head unit does not solve the problem, the move the grounding point

of the head unit. Hopefully the noise will be gone, and you can

install the head unit with a quiet ground and proceed to level 5,

otherwise go on to level 3.

2.1.3 Level 3: Move the Head Unit

----------------------------------

The amplifiers are fine, but moving both the ground for the head unit

and the signal cables does not solve the noise problem. Take the unit

completely out of the dash, and put it on either the seat or carpet,

and run new signal cables to the input of the amp. If this solves the

problem, re-install the head unit, one step at a time and skip to level

5. But if the noise persists, then move the head unit as close to the

amp as possible and use the shortest possible signal cables. This will

verify that the original signal cables are not causing the problem -

assuming the noise is gone, reinstall the head unit one step at a time

and go to level 5. Otherwise, there may be a problem with the power

filtering for the head unit. As with the amps, power the head unit

with an isolated power supply (again making sure that the head unit

isn't touching the car's chassis at all). If the noise goes away, you

can add power supply filtering or an isolated power supply; go to

level 2. But if the isolated power supply does not solve the problem,

then you can either replace the head unit and go to level 2, or check

the car's electrical system in level 4.

2.1.4 Level 4: Testing the Car

-------------------------------

There does not seem to be a problem with either the head unit or the

amplifier, and the car's charging system is suspect. To see if this is

the case, we can use a system in a car that is already known to be

"quiet." Bring both cars together as if you were going to jump one,

and use jumper cables to connect the two batteries. Start the engine

of the car with the noise problem, and listen to the "quiet" car's

system. If the noise does not go away, there is a SERIOUS problem with

your car's electrical system (possibly a bad alternator). Have a

qualified mechanic check the charging system out. If there is no noise

in the "quiet" car, then the "noisy" car's charging system is

definitely quiet, so continue with level 5.

 

[stones 10+ year member]

Con't-

2.1.5 Level 5: Adding Signal Processors

-----------------------------------------

We have proven that the amplifiers are good, the head unit is good, and

the car's electrical system is good. Now we need to reconnect each

signal processor. Repeat this level for each signal processor used in

your system; if you have added all of your signal processors, and

there is no longer any noise, CONGRATULATIONS! You've removed the

noise from your system! Connect the signal processor. If there

isn't any noise, then go on to the next signal processor. Otherwise,

try re-routing the signal cables. If this cures the problem, the route

them permanently over the quiet path, and install the next processor.

If not, then isolate the processor from the car's chassis except for a

single grounding point. If this works, then permanently isolate the

processor, and move on to the next processor. If isolation does not

help, then advance to level 6.

2.1.6 Level 6: Processor Isolation Tests

------------------------------------------

Now, noise enters the system when one particular processor is

installed, but regrounding it does not help. Move the processor very

close to the amp, and check for noise again. If there isn't any, then

re-install the processor, carefully routing the cables to ensure no

noise, and continue at level 5 with the next processor. Otherwise, use

an isolated power supply to power the processor, making sure that no

part of the processor is touching the car's chassis. If this solves

the problem, the consider permanently installing an isolated power

supply or possibly a 1:1 transformer, and go to level 5 with the next

processor. Otherwise, separate the processor and isolated power supply

from the car by many feet and re- test. If there is still noise, then

there is a serious problem with the processor's design. Get a

different processor, and continue at level 5 with it. If separating

the power supply and processor from the car does solve the noise

problem, then either the processor is damaged, or your tests were

inaccurate. Repeat level 5.