loaked

Has anyone installed a full range amp to power their door speakers and NOT gotten engine noise?

If so where did you ground the amp too???

I have an 06 E350(W211), and have had the amp grounded to the battery, and am getting engine noise. I tried a few other spots around the trunk and it just wont go away. I'm not sure what I am doing wrong. This car is such a pain to do anything to.

Thanks for any suggestions.

loaked

Jesus, no ones ever put an amp in there car?

damedash

added an amp to my 2004 c240, all bad, so much engine noise, tried different grounding points still no luck, what i ended up doing was grounding my RCAs..(my deck RCAs)..acts as a noise filter..try that out

jbondox

I have done many.... but how would you want us to fix it? what type of amp, how did you make your connections, where did you get the signal, what did you use to get the signal...etc...etc... etc...

pinebaron

Check your messages.

rob13572468

Its the old "Hi, my car is broken, does anyone know what I need to do to fix it?"

jbondox

you know it!

pinebaron

Oh Yeah?

jbondox

:sigh:

loaked

Well there is a lot more to it than that. I have found help elsewhere with this problem. The problem is a lot more involved that what most people can help with, and I admit I didnt describe the problem in full, but its such a one off random issue it would take a full page to properly describe. I was just posting this as a feeler to see some responses.

After posting on many car audio forums with no luck, hours upon hours of troubleshooting and no luck, but some great help from a few members here, I have figured out the cause of the problem.

Fixing it however is a whole other story... It appears the amp is picking up electical noise from the alternator/regulator somehow.

And if anyone is very knowledgeable with the MB electical system as far as the alternator and regulator, and this interfering with other elelctronics, please PM me, if a solution can be found I would be willing to pay someone for thier time. I know car audio like the back of my hand, done it for years, but when it comes to vehicle mechanics/electonics I dont even know where to begin.

vherok

Hi Loaked

My experience in this is that the AMP is usually grounded poorly, the grounding wire should be as short as possible and at least as large as the positive cable or bigger. Can not stress enough that the ground is even more important than the positive lead, other than it does not need to be fused as the positive side should be. Be sure the amplifier itself is isolated from the car chassis.

Sometimes the signal source to the amplifier is picking it up on its way there. Make sure the signal leads to the amplifier are not running parallel in close proximity to any existing 12 volt power leads in the car. As power wires give off a small magnetic field as current runs through them they can influence the signal running along wires that are very close. Shielded cables can help a lot, but nothing is better than a thoughtful installation.

v

rob13572468

Hey I understand your frustration; the problem with most car audio forums is that alot of guys (most) on there do not understand what they are doing (success hooking up car audio equipment does not equate to understanding.)

Fortunately for you both jim (jbondox) and I are experts with both audio and mb electronics so you are in the right place to get a proper answer but you are going to have to give to get... Post up everything you ahve done so far and exactly what you have in there and we'll go from there...

jbondox

Rob = EXPERT .... me = smartarse with a itty bit of knowledge

loaked

Ok, here goes, its a lot to write so bare with me here:

The amp makes noise. Its a 2ch amp going to the front speakers.

It makes this noise only when the engine is on.

And after you start the engine, it takes a full 3 to 5 seconds before the noise kicks in.

It makes the noise with NOTHING, i repeat, NOTHING plugged into the RCA's.

It makes this noise with 2 different amps.

The noise only comes out of 1 channel on the 2 channel amp(which is wierd).

The noise isnt engine wine, it doesnt change with the revs of the vehicle. Its a constant noise. It sounds like white noise I think you call it. Or like a FM radio station that doesnt come in. Like a hissing sound.

It makes this noise with the amp not mounted to anything, just laying there on the carpeted trunk.

It makes this noise with the amp grounded to anything in the car's chassis. The battery, the same place the stock amp is grounded to, and 3 other new ground I created. I created these grounds myself, and they are as solid as they get.

It makes this noise even with a test bookshelf speaker hooked up setting on a small table outside of the car.

I have spent, no joke, 9-12 hours trouble shooting this issue. I have done at least a hundread systems over the years. This is my first Mercedes, which happens to be mine. I have NEVER had a noise issue like this before, ever. All my old installer buddies who are much more skilled than I am, have absolutley no clue. And they all agree on one thing, they just dont do them (Mercedes Benz's).

jbondox

how are you getting the signal?

all those other forums and they never asked if you used a set of muting plugs to the amps input to see if the noise goes away?

Basically a muting plug is an RCA plug with the shield and the signal (both wires) twisted together. you can make them out of a set of scrap RCA's.

you stated that you did 100 systems... this is simple troubleshooting 101, and would take 15 minutes max

sooooo....

if you start out with muting plugs, the gains turned way down, and you get no noise... everything after the amp should be fine... if you still get noise then start looking at your speaker wires ran to the speakers...

if you are using passive crossovers, remove them out of the loop and just hook up the midbass... does it fix the problem? if you are still having the problem after the muting plugs. passive crossovers pick up noise, but seeing your noise sounds like it is signal related.... I am betting it is before the amp and is a gain issue

what type of amp... as in name and model number... not 1,2,4 channel

what are using to take the signal off the audiogateway/amp... and I am hoping that is where you got the signal... and if you didn't... nevermind...

how did you send the signal from the amp to the front speakers?

are you using a line out converter... something quality? what make and model

how do you have it hooked up?

let me know the colors that you used for the signal to the converter (if used) and the colors going to the speakers

loaked

Well I didnt try muting plugs, because it makes the noise with nothing plugged into the rca's at all. I wouldnt think muting plugs would really matter, so I will try them out for sure.

I dont think it has to do with passive crossovers, because when the speakers are ran of the factory amp, everything is fine. Again, I get this noise with a bookshelf home speaker just plugged into the amp and set outside of the car with maybe a 3' wire.

The noise is the same weather the amp gain is set to zero or turned up, no matter what crossover is turned off/on, etc.

The amp is a Diamond Audio D400.2 amp. It was purchased brand new. 100x2 @ 4 ohms.

I am tapping into the wires from the AGU(factory amp), to a schoshe high to low lever converter, then RCA's to amp. I messed with the level on this and the gain on the amp pretty extensivly, and the noise stayed constant no matter what, even with both the amp and converter levels set to zero.

The colors where blk/blkbrn for front right, and grn/grnblk for front left.

rob13572468

where in the vehicle are you getting power for the amplifier?

jbondox

dude...

muting plugs on all the inputs

do you have noise?

yes, look at the amp or the passives, including the speaker wire

no, get rid of that junk scosche piece and get a real converter, try JL, or just buy a modern amp with high level inputs as the 400.2 is 5 years old

loaked

Ok tried the muting plugs last night, no difference.

Regarless of age of the amp, or what type of inputs has no bearing on THIS issue, I wish it did, thats would be easy to fix, but its not.

And again, I am still getting the noise with a bookshelf speaker. A test speaker I have taken from my house to use to plug into the amp and the noise is still there, no differences.

I have even tried this with my other amp too, its a Mmats 1500.2d. It makes the exact same noise. And the noise being produced is of a higher frequency than a class D amp can even produce.

Actually now that I am thinking about it I should just unhook all the other stuff from the battery and just straight battery to amp. I got some ideas now.

Its got to be something with the power. And there has to be some kind of interference there with it.

I am getting power to the amp from the battery in the trunk.

If I had an external power source I could test the amp that way and would really help figure out this problem. I need to find someone with an extra battery or something, or I guess I could pull the battery out of my other car and test it that way... Would a battery charger work? I do have one of those.

rob13572468

The bookshelf speaker that you hooked up is literally the only thing connected, right? (e.g. you have RCA's disconnected, power/gnd/remote hooked up, and one channel direct to the bookshelf speaker with no xovers in between and no other speakers connected...) if thats the case then it is indeed a problem with the power going into the amplifier...

You should have both power and ground going direct to the battery terminals in the trunk.. make sure that both battery terminals are tight. The fact that both amplifiers have the same problem means that its either a charging issue (bad alternator), a battery issue (one internal cell is shorted), or connection issue (battery to amp or alternator to battery cables are loose).

Start by checking the cables and connections and make sure something isnt loose. run power and ground direct to the battery using 24" or less of cables. What size cables are you using... should be 4 gauge minimum... Check all that and report back because if its not that then the next step is to get a oscilliscope and start probing the power leads to the amp and the speaker outs to see exactly what the noise is.


do NOT try to hook the amp direct to a battery charger... it can damage the amplifier...

loaked

Only thing hooked up to the amp is power, ground, remote, and one channel to a book shelf speaker thats it. No RCA's, no other speakers, no other type of anything.

Your second paragraph... THANK YOU! Now where finally getting somewhere... There is defiantly a problem with the power, and O N L Y when the engine is on. Thats why I am thinking its something with the alternator, and or the power source in general, like the battery. Finally after explaining this issue someone realizes. Nothing like repeating myself 5 times that I am getting this problem without RCA's, only to be told to check the RCA's... Regardless, I have received the most help from this site than any others so far, so I cant complain. Any who...

If it was a problem with the battery itself I would be having issues with or without the engine on right?

Thats why I was wondering if anyone on here knows about the alternator/regulator, and how it would be affecting the amplifier. OR if a filter of some kind on the power wire would help as well. I read somewhere about a bad diode in an alternator causing noise problems, but I cant seem to find the article now. Could this be a possibility as well?

But all the cables are about as tight as a connection as you can get before something gets stripped out. I am using 4 gage wiring, DIRECT TO THE BATTERY IN THE TRUNK. Straight to the positive and negative terminals. And I have tried several other ways of grounding the amp, still getting power from the positive terminal from the battery in the trunk. The amp sits less that 1 foot away from the battery in the trunk.

rob13572468

Yes, a bad diode is what i was getting at.. The alternator has 3 phases (3 sine waves 120 degrees apart are combined to create DC which is then filtered with capacitors to remove ripple. The problem is that if one phase is damaged (either by a broken coil wire inside the alternator or a bad diode) then the amp may not be able to compensate for the resulting large ripple in the line. The real question is what frequency the noise exists at; If we can find out or even make a good guess then you can try a filter cap to remove smooth out the signal...

loaked

I see where the oscillioscope would come in handy here. Maybe I can find someone with one to let me use at there house real quick. Or an audio shop here in the Phoenix area. I think my grandpa may have one, but it would be from the 60's, will that still be able to tell me the frequency?

All I can say about the frequency is it high pitched. It can only be heard through the tweeters. I put my head right up to the midbass speaker in the door and couldnt hear a thing. It sound like an FM radio station thats not comming in, and it makes my tweeter crackle a little bit at mid to high volume.

If I can get an o'scope what frequencys should i be looking for? I have never used one, so I may need to educate myself elsewhere before hand.

jbondox

maybe it is time to throw in the towel and go have it installed professionally. I doubt it has anything to do with the power

loaked

I used to install professionaly, one of my best friends still installs professionally, and has been for 9 years now, and he could not make any sense of it, or locate the cause of the issue. And my other long time friend I had look at it broke a USACi world record in Kansas a few years back for his class. He is a car audio genius, and used to have an oscilliscope But he could not even figure out what is causing this. He did mention that he has heard of an alternator giving bad noise, but like me and my other friend, we just dont know anything about car mechanics/electronics. Having it 'professionally' installed will just be a waste of even more peoples time, and my money. Most installers that work at car audio shops wont even touch a Mercedes, let a lone be able to figure this out. I have read a lot of posts in this section of the forum, and jbondox you give a lot of good info to people and are very knowledgable, but if you cant even figure it out, some douche at a car audio shop would probably make the problem worse, if thats even possible lol.