27 replies to this topic

[RawlinsGTR]

Hi all,

Had a trawl through the forum this morning and couldn't find an answer about this;

My speakers made a constant popping noise (not too loud, but it gets louder as I turn the volume up) when I'm listening to the radio in my car.

I did (up until today) have an old head unit that didn't quite work properly, and the speakers only did this popping when listening to the radio; CD or Aux and they didn't make that noise.

I installed my new headunit I got for Christmas today, and had a test just to see if the popping noise was still there. It's the same problem; only when listening to the radio.

Also, another thing I found; I only get it on some channels, such as Capital. Heart and Radio 1 are all fine unless I turn it up quite loud, and then it's faint. But on Capital, it's pretty much always there.

The speakers I have are pretty poor, and came with the car when I bought it off the previous owner. I'm going to be changing them to <50W RMS speakers (when I've decided what ones) soon and putting an amp I have in.

Now, the question;

Does anyone have any idea why the popping noise occurs, and why it's only on certain channels and only on the radio? Is is simply interference, or should I be checking the aerial wires and things?

Thanks to all those who advise,

Simon.

[Ruckus]

Does this only happen when the car is running or all the time?

[freshairmini]

Could it be some kind of interference from some of the cars electronics, as on the alternator you get those suppressor things?

[RawlinsGTR]

Ooh, haven't tried it without the car running. You mean just the ignition, correct?

[Ruckus]

Ooh, haven't tried it without the car running. You mean just the ignition, correct?

If you need to have it on for the headunit to work then yes.

Also how fast is the poping.
1 a second or faster??

[RawlinsGTR]

Okay, just tried it all.

The popping only occurs when the engine is running, but sometimes it doesn't happen at all.

The popping is definately faster than 1 a second :)

Any advice?

Cheers,

Simon.

[Ruckus]

Disconnect the alt or take the belt off (remember no water pump) and run the car briefly and test again.

Also do you have resistor sparkplugs? ie 'NGK R'
Also check your engine earthing straps and do you have an earth strap from the alt to the chassis?

This sounds like RF from the engines electrical system, the question is what bit is making the noise.

[RawlinsGTR]

Thanks Ruckus. I'll do that tomorrow.

I'll check the spark plugs and earthing straps.

P.S. - Just to check, you mean alternator when you say "alt?"

Edited by Dog., 01 January 2012 - 09:46 PM.

[Ruckus]

P.S. - Just to check, you mean alternator when you say "alt?"

Yep

[RawlinsGTR]

Ruckus:

1. Yeah, I do have resistor spark plugs.

2. I could only find one engine earthing strap, but it looks alright to me:


3. I've got a picture here of the connections to the alt, and I'm pretty sure the singular one is the earth strap, if I'm correct? Also, do I need to disconnect both of these and then run the car briefly? Just wanted to check and be safe :)


Thanks,

Simon.

[TA2DMAC]

You have a ground loop. You need run the ground( earthing) from you radio to the same ground as your car. you basically have a loop from your current ground of the radio to other grounds. Also clean your ground to make sure you get a good solid connection.

[Ruckus]

Yes you can disconnect both cables, but you only really need to remove the big one.

The big one carrys the power to the Solonid > battery.
The little one is the switch on trigger switch for the alt.

Disconnect the + on the battery before the cable on the Alt.
Once the alt cable is un-bolted be sure to wrap it in something to insulate it as it will be live when you re connect the battery to start the car.

[RawlinsGTR]

Great, I'll go try that now, thanks.

[RawlinsGTR]

Right, just tried it without the alternator plugged in, and I still got the popping noise.

You might be right TAD2DMAC. I'll need to check the radio ground. I thought that it was already wired into the plug, but since it did the same thing with the previous headunit, I might have thought wrongly?

[Ruckus]

If you have not got the ground cable to the headunit wired correctly then the unit will ground via the aerial or it's chassis. This will create the ground loop problems as said.