the12volt.com spacer
the12volt.com spacer
the12volt.com spacer
the12volt.com spacer
icon

Yet another noise problem


Post ReplyPost New Topic
< Prev Topic Next Topic >
energumeno 
Member - Posts: 1
Member spacespace
Joined: July 31, 2005
Location: Mexico
Posted: July 31, 2005 at 11:50 PM / IP Logged  

Hi,

A few days ago i took my 2000 Jetta to have a deler install a MTX Thunder amp and a Sub that I used to have in my previous car. I still haven’t bought a new head unit so I used the original car stereo to feed the amp for now.

Everything seemed to be working fine but yesterday I noticed that whenever the car is turned on and stopped some noise is heard on the speakers and sub, this is most noticeable in the sub that in the rest of the speakers. The symptoms are the following,

- When I press the gas pedal the noise seems to be much less (as long as the engine has enough revs)
- There is no noise at all when the car is turned of and, of curse, the stereo is turned on.
- The same amount of noise is present regardless of the volume setting on the stereo.

I also noticed that, at night, sometimes the car lights lightly blink when the car is stopped. Since I changed the car battery a couple of months ago, I assumed that the entire problem might come from my alternator.

After reading posts regarding noise for about two hours I decided to do some basic testing on my system in order to confirm my thoughts about the alternator being the cause of the problem. This is what I did,

- Checked the cable runs. The power cable is run thru the driver’s side and the input RCAs on the passenger’s side

- Checked the Amp ground. It just has a short length tick cable connected to a bolt that also holds the rear seat belt, it seems to be making good contact with the car’s chassis
- Checked that the remote wire. It was run as a separate blue cable to the amp
- Assuming that the problem could be on the remote wire, disconnected it from the amp and bridged the power terminal to the remote terminal. The problem stayed exactly the same.
- Disconnected the RCA inputs on the AMP. This made the noise to disappear; if these terminals are disconnected I get no noise either if the car is off or on.
- Brought my laptop to the car and connected it to the AMP inputs. In this scenario I don’t get any noise either if the car is off or on

This made me think. If the problem was the alternator inducing noise on the amplifier power feed, I would get noise on the sub whenever the car was turned on regardless if the car stereo or my laptop was feeding the AMP.

My newbie conclusion is that the problem may be related to two possible causes,

1. RCA cables that run from the car stereo to the AMP are somehow damaged (this doesn’t seems very likely, I assume that if this were the case, I would get noise either if the car is off or on.)
2. Bad Alternator inducing noise on the car stereo. This seems more logical, perhaps the power supply in the AMP is better than the one on the car stereo, this may allow it to run fine while the car stereo is having problems. However this assumption does not completely convince me since I was using the same stereo with same alternator before installing the AMP without problems. Perhaps the stereo’s pre amp outputs are more sensitive to noise or something like that…

Well, anyway if somebody has any idea or thought on what can I do to solve this problem it would be greatly appreciated

geepherder 
Platinum - Posts: 3,668
Platinum spaceThis member consistently provides reliable informationspace
Joined: October 27, 2003
Posted: August 02, 2005 at 9:05 AM / IP Logged  

First, I want to congratulate you on an well-thought, informative post.  Many times users will only give us symptoms, and want a quick solution to their problem.  At this same time, they'll give us no description of make/model, what gear they have, what they've tryed so far, etc.

You should really have the stereo shop take a look at it.  Since they installed everything, check with them and they should have a solution.  You shouldn't be charged anything, since you didn't do anything that would have caused it.

If you do want to just fix it yourself, it sounds like you've actually done the hard part, and narrowed the noise down to the signal input.  Since the amplifier in this car is below the rear deck, on the passenger side, I'd check to see if they got signal there first, or perhaps the rear speakers.  Many times line-out-converters will come with a couple wires that you can ground if you have noise problems.  I've never used these before.  If these wires are grounded, try disconnecting them (tape them off so they can't touch to ground) and see if the problem goes away.  Ensure all the connections are good.

My ex once told me I have a perfect face for radio.
acopsy88 
Member - Posts: 26
Member spacespace
Joined: July 31, 2005
Location: United States
Posted: August 05, 2005 at 12:08 AM / IP Logged  

It could be a bad ground

2 12 inch jl audio w3s stock infinity sound eclipse deck memphis 1000d

Sorry, you can NOT post a reply.
This topic is closed.

  Printable version Printable version Post ReplyPost New Topic
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot delete your posts in this forum
You cannot edit your posts in this forum
You cannot create polls in this forum
You cannot vote in polls in this forum

  •  
Search the12volt.com
Follow the12volt.com Follow the12volt.com on Facebook
Thursday, October 31, 2024 • Copyright © 1999-2024 the12volt.com, All Rights Reserved Privacy Policy & Use of Cookies
Disclaimer: *All information on this site ( the12volt.com ) is provided "as is" without any warranty of any kind, either expressed or implied, including but not limited to fitness for a particular use. Any user assumes the entire risk as to the accuracy and use of this information. Please verify all wire colors and diagrams before applying any information.

Secured by Sectigo
the12volt.com spacer
the12volt.com spacer
the12volt.com spacer
Support the12volt.com
Top
the12volt.com spacer
the12volt.com spacer