Just installed new head unit popping noise when changing inputs.
Senior Member
Joined: Feb 2013
Posts: 320
Likes: 6
From: DFW
2 2001 E320s, 2005 E320 4Matic
If I remember correctly, you can't use the PAC OEM with the GLI. Not sure, so you better check. If you have a solid chassis ground, you should not need the GLI. I still think you either have a corrupt ground loop, or alternator/voltage regulator issue. You should also check the ground strap for rust, corrosion etc. Something unique to your setup is causing noise that others don't experience.
Sorry I could not have been of more help. Keep posting as you get the PAC unit.
Sorry I could not have been of more help. Keep posting as you get the PAC unit.
Thread Starter
Super Member
Joined: Feb 2013
Posts: 862
Likes: 28
2010 e550 coupe
If I remember correctly, you can't use the PAC OEM with the GLI. Not sure, so you better check. If you have a solid chassis ground, you should not need the GLI. I still think you either have a corrupt ground loop, or alternator/voltage regulator issue. You should also check the ground strap for rust, corrosion etc. Something unique to your setup is causing noise that others don't experience.
Sorry I could not have been of more help. Keep posting as you get the PAC unit.
Sorry I could not have been of more help. Keep posting as you get the PAC unit.
Senior Member
Joined: Feb 2013
Posts: 320
Likes: 6
From: DFW
2 2001 E320s, 2005 E320 4Matic
There should be zero noise with the engine off. With the engine off, there is nothing to make noise, other than maybe FM static.
Last edited by RichM; Apr 11, 2013 at 05:54 PM.
Thread Starter
Super Member
Joined: Feb 2013
Posts: 862
Likes: 28
2010 e550 coupe
What could be causing noise when the engine is not running? Could the head unit simply be defective? Like I said the noise is extremely faint and can easily be missed the only way I was able to notice it was by alternating between standby mode (no noise) and one of the inputs like cd or aux.
Senior Member
Joined: Feb 2013
Posts: 320
Likes: 6
From: DFW
2 2001 E320s, 2005 E320 4Matic
May be the head unit. With a CD in the drive and turning, you may have some mechanism noise, and in AUX with an IPod attached you may be picking up noise from it.
With nothing attached to AUX or no CD in the changer, if you turn it up to full vol how loud is the noise. Is it like a white noise or a hum or a whine like with the engine running prior to fixing the ground?
Then again, you may be looking for gremlins that are not there, and you are being hyper critical.
With nothing attached to AUX or no CD in the changer, if you turn it up to full vol how loud is the noise. Is it like a white noise or a hum or a whine like with the engine running prior to fixing the ground?
Then again, you may be looking for gremlins that are not there, and you are being hyper critical.
Last edited by RichM; Apr 11, 2013 at 07:14 PM.
Thread Starter
Super Member
Joined: Feb 2013
Posts: 862
Likes: 28
2010 e550 coupe
May be the head unit. With a CD in the drive and turning, you may have some mechanism noise, and in AUX with an IPod attached you may be picking up noise from it.
With nothing attached to AUX or no CD in the changer, if you turn it up to full vol how loud is the noise. Is it like a white noise or a hum or a whine like with the engine running prior to fixing the ground?
Then again, you may be looking for gremlins that are not there, and you are being hyper critical.
With nothing attached to AUX or no CD in the changer, if you turn it up to full vol how loud is the noise. Is it like a white noise or a hum or a whine like with the engine running prior to fixing the ground?
Then again, you may be looking for gremlins that are not there, and you are being hyper critical.
MB World Stories
The Best of Mercedes & AMG
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
10 Most Reliable Mercedes-Benz Models You Can Buy Used
Verdad Gallardo
Senior Member
Joined: Feb 2013
Posts: 320
Likes: 6
From: DFW
2 2001 E320s, 2005 E320 4Matic
Just out of curiosity, did the original radio make the same noise? As for the heat, yes it should be warmer than the original unit, but not so hot that it is uncomfortable to hold. If your OEM unit did not make the same white noise, then the new head unit may have problems. Talk to the folks you bought it from. See if they will send you an exchange.
Thread Starter
Super Member
Joined: Feb 2013
Posts: 862
Likes: 28
2010 e550 coupe
No the stock unit had no sound issues the cd changer was going out and the volume control was a little iffy so I thought I'd upgrade to something newer with more features I didn't think all this would be necessary.
Senior Member
Joined: Feb 2013
Posts: 320
Likes: 6
From: DFW
2 2001 E320s, 2005 E320 4Matic
It usually isn't. These installs are usually pretty straight forward. On one particular install I did for a friend, we had ground noise, but a ground lead though the firewall to the engine bay to get a good ground solved the problem. This was on a Chinese direct sourced head unit. I have never had to use the GLIs, but always use a PAC OEM2 or the new replacement. I like the old PAC better than the newer unit.
Thread Starter
Super Member
Joined: Feb 2013
Posts: 862
Likes: 28
2010 e550 coupe
How are you running the grounds I don't solder so I found an area right near the hood release where I secured the wire with rubber surrounding it. My other option would be to run one of those alligator clips but I'm not sure if grounding is the issue because all these have solutions make no noticeable difference.
Senior Member
Joined: Feb 2013
Posts: 320
Likes: 6
From: DFW
2 2001 E320s, 2005 E320 4Matic
How are you running the grounds I don't solder so I found an area right near the hood release where I secured the wire with rubber surrounding it. My other option would be to run one of those alligator clips but I'm not sure if grounding is the issue because all these have solutions make no noticeable difference.
Thread Starter
Super Member
Joined: Feb 2013
Posts: 862
Likes: 28
2010 e550 coupe
The type of noise you are experiencing now is not ground. With the engine running, ground noise is that rising and falling whine when accelerating, or just a steady whine while the engine is running. It goes away when you turn the car off. Ground termination is not soldered. A metal to metal surface where there is a nut and bolt is all that is needed. The only place you would solder is the line from the harness to the line from the head unit. You can also use a butt connector, spade connector or as you did a wire nut.
Senior Member
Joined: Feb 2013
Posts: 320
Likes: 6
From: DFW
2 2001 E320s, 2005 E320 4Matic
I just put the stock mbz hu back in just to see what would happen and it also makes this faint hiss noise when the engine is not running (guess you don't notice things till you work on them). I am thinking of having an installer just bypass the bose amp as this is becoming way too time consuming. The installer at bestbuy said that if he bypasses the bose amp there will be no ground noise and no popping and i wont need the gli's or the crutchfield harness with the rca's (they use a strictly speaker wire harness). Should I believe this or if im hearing ground noise now am I likely to still hear it even if he bypasses the amp and does all this stuff.
Since the radios internal amp wattage is rated at 4ohm, you will experience heat buildup in the head unit as the impedance is cut in half. This will shorten the life of the head unit, or possibly cause it to fail outright due to overheating. You also have to remember, these speakers were designed to work with this amp. You may not like the sound quality without it. At higher volume levels, you will most likely get distortion. The sound will not be as clean.
At this point, I would expect the white noise you hear with the engine off will be there regardless. But then again, you are not happy with the way it is, so other than a few bucks and a butchered wiring harness, what do you have to loose.
Last edited by RichM; Apr 12, 2013 at 10:43 PM.
Thread Starter
Super Member
Joined: Feb 2013
Posts: 862
Likes: 28
2010 e550 coupe
Just so we are clear, the noise you are hearing with the engine off is not ground noise. Where this noise is coming from I can't say. It may be coming from the Bose amp, maybe not. I don't know how the installer can say with any certainty the noise will not be there. It may, it may not. As for ground noise, if you were having issues before, you will likely have them without the Bose amp. I don't believe the amp is the cause or source of the ground noise. Remember, ground noise is the whine you heard with the engine on. Will this get rid of the pops? Yes, this I can say with certainty.
Since the radios internal amp wattage is rated at 4ohm, you will experience heat buildup in the head unit as the impedance is cut in half. This will shorten the life of the head unit, or possibly cause it to fail outright due to overheating. You also have to remember, these speakers were designed to work with this amp. You may not like the sound quality without it. At higher volume levels, you will most likely get distortion. The sound will not be as clean.
At this point, I would expect the white noise you hear with the engine off will be there regardless. But then again, you are not happy with the way it is, so other than a few bucks and a butchered wiring harness, what do you have to loose.
Since the radios internal amp wattage is rated at 4ohm, you will experience heat buildup in the head unit as the impedance is cut in half. This will shorten the life of the head unit, or possibly cause it to fail outright due to overheating. You also have to remember, these speakers were designed to work with this amp. You may not like the sound quality without it. At higher volume levels, you will most likely get distortion. The sound will not be as clean.
At this point, I would expect the white noise you hear with the engine off will be there regardless. But then again, you are not happy with the way it is, so other than a few bucks and a butchered wiring harness, what do you have to loose.
Senior Member
Joined: Feb 2013
Posts: 320
Likes: 6
From: DFW
2 2001 E320s, 2005 E320 4Matic
Well the white noise that goes while the engine is off I can live with but no matter what scenario I run ground to chassis etc I still get that whine (ground noise) it happens unpredictably but usually when i am going downhill in low gear i can really notice it. The ground noise is what the installer said he would be able to solve he said the thick brown ground wire coming from the mbz harness is sufficient. With the stock mbz hu i never had any ground noise. Another thing I've noticed is that without the gli's I have the popping but there is no ground noise. Could my issue be cheap gli's?
Typically, the ground from the MBZ harness is sufficient. If you want to run a ground wire to the engine bay, remove the knee bolster and under tray from the passenger side footwell. Peel back the carpet and sound deadening materials. Once you do this you will find where the grounds from the wiring harness go thru the firewall. You may be able to snake a wire thru there. What I did, was to drill a small hole, run a wire thru to the engine bay using a fish wire. Standing in front of the car looking into the engine bay, behind the coolant reservoir, you will see a ground point. There are a bunch of brown wires attached to ground stud. This process however is a last resort measure that I do not recommend. In my case, we had no way to return the head unit as it was a direct from China system with a return policy that only accounted for DOA systems.
One question, where is your installer planning on picking up the leads going to the speakers to bypass the Bose amp?
Last edited by RichM; Apr 13, 2013 at 09:16 AM.
Thread Starter
Super Member
Joined: Feb 2013
Posts: 862
Likes: 28
2010 e550 coupe
So let me see if I have this straight. If you remove the GLIs, there is no engine whine, just the popping noises when changing functions? If this is correct, this is good. The GLIs deaden the sound muddying the bass and thinning out the treble response. Since you have a PAC OEM2 coming, I would give that a try prior to cutting into the wiring harness. The PAC OEM2 will solve the popping noises.
Typically, the ground from the MBZ harness is sufficient. If you want to run a ground wire to the engine bay, remove the knee bolster and under tray from the passenger side footwell. Peel back the carpet and sound deadening materials. Once you do this you will find where the grounds from the wiring harness go thru the firewall. You may be able to snake a wire thru there. What I did, was to drill a small hole, run a wire thru to the engine bay using a fish wire. Standing in front of the car looking into the engine bay, behind the coolant reservoir, you will see a ground point. There are a bunch of brown wires attached to ground stud. This process however is a last resort measure that I do not recommend. In my case, we had no way to return the head unit as it was a direct from China system with a return policy that only accounted for DOA systems.
One question, where is your installer planning on picking up the leads going to the speakers to bypass the Bose amp?
Typically, the ground from the MBZ harness is sufficient. If you want to run a ground wire to the engine bay, remove the knee bolster and under tray from the passenger side footwell. Peel back the carpet and sound deadening materials. Once you do this you will find where the grounds from the wiring harness go thru the firewall. You may be able to snake a wire thru there. What I did, was to drill a small hole, run a wire thru to the engine bay using a fish wire. Standing in front of the car looking into the engine bay, behind the coolant reservoir, you will see a ground point. There are a bunch of brown wires attached to ground stud. This process however is a last resort measure that I do not recommend. In my case, we had no way to return the head unit as it was a direct from China system with a return policy that only accounted for DOA systems.
One question, where is your installer planning on picking up the leads going to the speakers to bypass the Bose amp?
The installer didn't specify how he would be bypassing the amp but does bypassing the amp mean I won't be able to go back to the stock radio if I wanted to?
Senior Member
Joined: Feb 2013
Posts: 320
Likes: 6
From: DFW
2 2001 E320s, 2005 E320 4Matic
That is like saying all cars are the same. PAC is a well respected brand, used by professional installers. Are they better or more effective than the brand you have? Don't know. If you have the $30 to spend, it may be worth getting one of the PAC OEM units. This will resolve the popping sounds, won't muddy the sound like a GLI can and boost and balance the signal from the radio. This is only if you are not getting engine noise without the GLI. If you are still getting engine noise the OEM will not help.
About direct wiring to the speakers. To bypass the Bose amp, the harness has to be hacked. This means cutting the harness connector off and direct wiring the speaker outputs to the existing speaker leads. If the installer left enough wire attached to the connector, you can try to patch the harness back together. Most cases this is a done deal. Once it is done, it is done. You can't go back. If at some point you plan on replacing the amp anyway, this may not be such a big deal.
Not sure where you are located, but if you have a high end (or higher end than BB) shop it may be worth stopping in to talk to them. The higher end shops can give you better info than BB.
About direct wiring to the speakers. To bypass the Bose amp, the harness has to be hacked. This means cutting the harness connector off and direct wiring the speaker outputs to the existing speaker leads. If the installer left enough wire attached to the connector, you can try to patch the harness back together. Most cases this is a done deal. Once it is done, it is done. You can't go back. If at some point you plan on replacing the amp anyway, this may not be such a big deal.
Not sure where you are located, but if you have a high end (or higher end than BB) shop it may be worth stopping in to talk to them. The higher end shops can give you better info than BB.
Senior Member
Joined: Feb 2013
Posts: 320
Likes: 6
From: DFW
2 2001 E320s, 2005 E320 4Matic
I spoke with a friend of my sons who owns an audio shop. The one of their specialties is upgrading audio systems where customers want to keep the Bose amp and speakers. They do mostly GM, and Japanese cars, but also some Audi and Mercedes. I sent him this thread to go over to see if we missed something. He said just because a head units preamp puts out 4v does not guarantee you won't get noise transmission, noise pickup or the popping sound. One thing he did mention, on your head unit you are able to set the volume for each function. I think he called it volume offset. He said to make sure the levels are set so that when you change sources the volume of that source is set to a low level. If the volume is set to high you will get a pop. Do this without the ground loop isolators installed. Also, they never do a Bose system without the appropriate PAC OEM kit.
He also related a bunch of other things, but I will post them later.
He also related a bunch of other things, but I will post them later.
Last edited by RichM; Apr 14, 2013 at 04:32 AM.
Thread Starter
Super Member
Joined: Feb 2013
Posts: 862
Likes: 28
2010 e550 coupe
I spoke with a friend of my sons who owns an audio shop. The one of their specialties is upgrading audio systems where customers want to keep the Bose amp and speakers. They do mostly GM, and Japanese cars, but also some Audi and Mercedes. I sent him this thread to go over to see if we missed something. He said just because a head units preamp puts out 4v does not guarantee you won't get noise transmission, noise pickup or the popping sound. One thing he did mention, on your head unit you are able to set the volume for each function. I think he called it volume offset. He said to make sure the levels are set so that when you change sources the volume of that source is set to a low level. If the volume is set to high you will get a pop. Do this without the ground loop isolators installed. Also, they never do a Bose system without the appropriate PAC OEM kit.
He also related a bunch of other things, but I will post them later.
He also related a bunch of other things, but I will post them later.
Senior Member
Joined: Feb 2013
Posts: 320
Likes: 6
From: DFW
2 2001 E320s, 2005 E320 4Matic
I did some reading this morning on your head unit. It seems each function has the ability to set the initial volume of each function. From the user manual.
Volume Offset: The level of each source may be independently adjusted to prevent radical leaps in output volume when switching from one source to another. The available settings range from -8 to 0 (-8 to +8 for Aux source).
It is a shame you have such crappy choices for local info. I want to be clear on this. If you choose to bypass the Bose amp, the installer has to hack the wiring harness. Once this is done, there is no going back. There is not an adapter that I am aware of that will match up to the Bose connector. The installer has to run some type of wire harness from the head unit to the trunk where he will disconnect the speaker harness from the amp. This is where he will hack. I don't know of a way to bypass the amp from the dash.
Volume Offset: The level of each source may be independently adjusted to prevent radical leaps in output volume when switching from one source to another. The available settings range from -8 to 0 (-8 to +8 for Aux source).
It is a shame you have such crappy choices for local info. I want to be clear on this. If you choose to bypass the Bose amp, the installer has to hack the wiring harness. Once this is done, there is no going back. There is not an adapter that I am aware of that will match up to the Bose connector. The installer has to run some type of wire harness from the head unit to the trunk where he will disconnect the speaker harness from the amp. This is where he will hack. I don't know of a way to bypass the amp from the dash.
Thread Starter
Super Member
Joined: Feb 2013
Posts: 862
Likes: 28
2010 e550 coupe
I did some reading this morning on your head unit. It seems each function has the ability to set the initial volume of each function. From the user manual.
Volume Offset: The level of each source may be independently adjusted to prevent radical leaps in output volume when switching from one source to another. The available settings range from -8 to 0 (-8 to +8 for Aux source).
It is a shame you have such crappy choices for local info. I want to be clear on this. If you choose to bypass the Bose amp, the installer has to hack the wiring harness. Once this is done, there is no going back. There is not an adapter that I am aware of that will match up to the Bose connector. The installer has to run some type of wire harness from the head unit to the trunk where he will disconnect the speaker harness from the amp. This is where he will hack. I don't know of a way to bypass the amp from the dash.
Volume Offset: The level of each source may be independently adjusted to prevent radical leaps in output volume when switching from one source to another. The available settings range from -8 to 0 (-8 to +8 for Aux source).
It is a shame you have such crappy choices for local info. I want to be clear on this. If you choose to bypass the Bose amp, the installer has to hack the wiring harness. Once this is done, there is no going back. There is not an adapter that I am aware of that will match up to the Bose connector. The installer has to run some type of wire harness from the head unit to the trunk where he will disconnect the speaker harness from the amp. This is where he will hack. I don't know of a way to bypass the amp from the dash.
Also my unit makes popping noises within an input like when switching tracks on a cd so I am not sure if switching the volume offset will work.
Last edited by Dnasty; Apr 14, 2013 at 02:49 PM.
