whiny noise

[Conn]

hey guys,

ive got this problem with my system in that there is a whiny noise whenever i accelerate and even if i dont it is constant. the only way for me to not hear it is to crank up the volume which can get annoying... i think ive been told that the headunit is making a motoring noise. it gets louder as the revs get higher and visa versa, help please?

 

[Tasmaniak]

It's alternator noise....tell us everything that your system consists of. Even if it's just stock.

 

[Ozzie]

You might need to buy a noise filter, there around 20 bucks from supercheap

 

[StoneX]

You never need to buy a noise filter. If there is noise, there's a problem that needs to be fixed.

Tell us what equipment you're using and how it's installed (like where cabling is run).

 

[Conn]

i bought my ute with everything installed in it, it had an old cadence head unit, coustic 4 ch amp and a JL tube sub... everything worked fine until i got a new pioneer headunit as a present that was installed and it all still worked fine but my neighbour is a sparky and said the wiring was done not quite right, however it didnt bother me cos it was all working. due to the area i live in i disconnect my tube sub every night and bring it inside with me, when i went to connect it back in the next morning my girlfriend started up my car while i was doing it and all of a sudden a loud noise went through the sub and speakers. i got a new cadence amp and replaced it and the noise is now ever since...

 

[StoneX]

Pioneer head units don't like the RCA's being unplugged and plugged in. They have a fuse inside on the RCA ground which blows and causes that noise. You need to get the head unit fixed.

 

[Conn]

will it cost much to get fixed and is it worth it?

 

[Haydz]

here is some info. taken from mobile electronics forum.


Eliminating Engine Noise
By - Russell Koehne (Kdog)

Every system has noise! It's a fact we have to deal with and limits what we can achieve in everyday life. If you have noise in your system then you can appreciate just how annoying it can be. Hopefully this tutorial will help you understand what is happening in your car and coupled with the noise debugging technique will alleviate your problem.

So what types of noise are there?

In the case of car audio we are only concerned with induced noise or EMI (Electro Magnetic Interference). RF noise is not usually a concern in cars because it can be easily shielded against. EMI on the other hand is low frequency magnetic noise that cannot be shielded against. EMI can get into the system in two ways through ground loops and through induced noise into the audio cables.

Where does it come from? Although our vehicles electrical system is powered by a battery, which should only put out DC our cars are usually used where our engine is providing the electrical power through an alternator. An alternator puts out an AC signal with quite a large amount of current. This is then rectified and placed on our cars electrical system to charge the battery and run the car. The alternator can cause a large magnetic field and is often the source for EMI in our cars electrical system. This usually appears as a whining sound that varies with engine speed. The high voltages used in our ignition system can also produce an electromagnetic field that causes noise. This usually appears as a ticking or clicking sound that varies with engine speed. If you have the latter type of noise you might want to check your ignition system and leads to make sure they are operating correctly.

The first thing to do before you start your noise hunting expedition is that your system has been level matched correctly. To do this you can read the gain setting tutorial. It is pointless to continue if you don't have your gains set correctly.

If you have alternator whine you are going to need a few components in order to find out where the noise is coming from. You will need some shorting plugs. These are simply RCA plugs/sockets with the two terminals shorted together. The first thing to determine is which speaker the noise is coming through. Once this has been done you can move to the amplifier through which this speaker is being driven. Remove all the RCA inputs from the amplifier and place the shorting plugs on all channels. Turn your system on. Has the noise disappeared? If it has then the amplifier and the associated wiring is OK and we can move to the next component. If the noise is still present then you may have some problems. Amplifiers usually have very good power filtering so you shouldn't have noise entering through these. Try another amp to see if it gets noise. Make sure the amplifier only has one ground (the proper power ground) and that the chassis of the amp isn't touching and metal of the car. If it is then remove it.

So we have decided that your amplifier isn't the problem. Lets move down to the next component. Plug the RCAs back into the amplifier. Disconnect them at their source and place the shorting sockets on their ends (remember to do this for all channels). Is the noise there now? If it is then your RCA cables are the problem and they need to be replaced (maybe with twisted pair). They may also be damaged somewhere. Assuming your RCAs aren't the problem plug them back into their source. Now disconnect the RCAs going into this source and replace them with shorting plugs. If you don't have a processor or crossover then you can skip to the head unit stage. Turn the system on. Is the noise their? If it is then you have found the problem. Once again make sure this unit has only one ground and remove all others. This device may have poor filtering or a poor design. In which case you may need to replace it with something else. Some units are notorious for creating noise problems. There are several tricks you can try though to help alleviated the noise from this unit. A power filter on the supply might help. Also a ground loop may be forming through the output RCAs. You will have to remove one of the grounds on one of your RCA cables to defeat this loop. This can be difficult and may be something you don't wish to do or you can add a RCA ground loop isolator.

If you haven't found the noise yet then continue to the next component. If you find that your head unit is the problem then try removing from the front of the car and take it down to where the amps are and play it from here. Chances are the noise is not there. In this case move it back to the front of the car. Once again make sure that it only has one ground. This can be hard if it mounts into the metal of the chassis. See if you can run it near where it is usually mounted but not touching the metal of the car. If he noise is not there then this ground loop is probably the problem. If you still get noise then you might want to add a power filter to the head unit's power. The head unit may be a poor design. To check for this you can replace it temporarily with another model or you can take the RCAs out from the head unit and place some RCA shorting sockets onto the end. If the noise goes away then you know that your head unit has bad filtering or has a high output impedance. Either way it may be time to replace it.

Remember that twisted pair RCAs will only fix your problem if you have induced noise through your cables. It will not fix the noise if you have a round loop or faulty components. You can read the twisted pair tutorial if you want to know why twisted pair cables can be superior to the normal RCA cables when it comes to noise rejection.

Happy hunting.


Ps. Its called alternator whine.

 

[roon_VR]

If you have a pioneer head-unit, chances are that it's a blown RCA fuse as StoneX stated. To eliminate the noise, take the head unit out, get two speaker wires that are about 20 cm in length, strip both ends of each speaker wire and make a hook on each end of the wires. Then, just simply place the hooked ends of the speaker wires into the RCA outputs of the headunit and put the RCA's in the outputs as well. it will be a tight fit with the speaker wires in there but they won't fall out. Then take the other two ends of the speaker wires and ground them to the chassis. That will eliminate almost all the whiny noises.

 

[garfa]

will it cost much to get fixed and is it worth it?

just buy a new one mate.