Noise in the 12v aux feed

[Cowboy Dave]

I've been playing around with a Belkin bluetooth device for transmitting music between ipad/iphone and the MMCS in my Triton.

It's like this one http://www.belkin.com/au/p/P-F4U037 except that mine must be an earlier model so doesn't come with the phone function.

Anyway in my centre console there are composite plugs for a video input to the head unit. Also in the centre console box is a 12v cigarette lighter style auxiliary outlet.

The belkin device comes with a little power plug that goes into the cigarette lighter and the 3.5mm headphone style plug then goes into a small y joiner to convert to RCA plugs for the audio in to the head unit.

So that all works pretty well but I've been getting 'noise' in the sound. I get two different kinds of noise, but both are only really audible in the quite bits between songs. Firstly, I get a quiet hum kind of background thing happening. Secondly, if I have the ipad on a charger when it's playing I get even worse noise.

I'm thinking that either I am getting interference or 'noise' in the 12v supply, or the wire from the device that carries the audio signal is picking up interference of some sort from the same 12v feed - there's not a whole lot of shielding or insulation or whatever on the wire, which is pretty thin to start with.

So, what I'm after, are tips on how I might be able to reduce the noise.

I recall when I was a kid you could buy a little filter to wire in but I thought modern vehicle electrics were a bit better than that. Also from memory the filter I'm thinking of either attached to the head unit or the aerial so that wouldn't help in this case.

Failing that perhaps I need to junk the belkin and try something else.

[helicoptercow]

I have the same thing, except I just have the ipod input mode with the 3.5mm jack. Different devices produce different volumes of interface too I noticed.

[odie602r]

If you haven't done it already, perhaps to eliminate the Belkin device as the problem run sound from your device simply through the 3.5mm sound cable, with everything else plugged into 12v source (barring the Belkin device).

Is the noise present? If not, it's the Belkin that's the problem. If there, then the Belkin isn't.

But are you using the Belkin to stream music via Bluetooth? It's just that you said you were connecting the audio via the 3.5mm lead that goes to the head unit - if I've understood this right, why do you need the bluetooth device at all?

(I've probably missed something really obvious )

[Cowboy Dave]

The audio connection is the audio out from the belkin. Why do I use this rather than just plugging in the ipad? No good reason, just because I like the idea of doing it wirelessly.

[MN GLXR]

Dave, go to Jaycar and get some ferrites and put them on the 12v and audio cables that connect to the Belkin device.

You can buy rings or clip on ferrites. If you get the rings you will need to wrap each cable around each ring numerous times. The clip on ones just clip on to the cable.

They will suppress the interference - but not always.

The guys at Jaycar can explain.....or PM me.

[odie602r]

I'd still suggest bypassing the Belkin with all else plugged in to 12v etc to see if the noise is from the Belkin unit - if you haven't already. Just eliminating possibilities.

This is a bit of a sidestep, but doesn't your model have built-in bluetooth? I'm assuming not, if you're trying out a 3rd party unit.

You're technically not doing it wirelessly though if the Belkin audio is then fed by cable into the audio head unit ...

[Cowboy Dave]

I have bluetooth but only for the phone functions, no music streaming.

As for wired/wireless, if we approach it your way then there's no such thing as wireless ever, since there's always some wires in there somewhere.

The reason I was exploring it to start with was that I was contemplating dash mounts for a tablet, and didn't want a bunch of cables running from the centre console all the way to the dash all the time. Also if I had bluetooth happening, and a passenger with music on their phone, all they'd have to do is pair with it and we could then listen to their stuff.

In terms of elimination - the fact that the interference/noise increases when the ipad is using a car charger suggests to me that there has to be some noise coming from that charger in some way.

[odie602r]

could it be the iPad charger itself then? Maybe try another one of those if you have a spare?

My MY12 GLX has bluetooth music streaming, so no wires at all

[Snooozy]

as was mentioned earlier,

I would give a ferrite filter a go

http://www.jaycar.com.au/productView.asp?ID=LF1294

[Cowboy Dave]

could it be the iPad charger itself then? Maybe try another one of those if you have a spare?

I've tried more than one charger. But it's not just the charger since I get similar noise from the belkin even when the ipad is charger free.

Will give the ferrite a go and see what happen.

I'm assuming this is some sort of alternator noise or similar? Would I get cleaner power from the second battery in the tray?

[odie602r]

Wonder if it's a similar thing then to what some people have posted re noise on their UHF when deriving power from the centre console or cig lighter plug.

Perhaps before you try a power source off the second battery you could run a temporary 'clean' power line straight from the main battery, just using some cable and do a makeshift lead (ie don't bother feeding it through grommets etc, straight from battery into cab).

[Mooons]

This noise you speak of is it only there when the engine is running
What other devices do you have plugged in
I know our GPS plays havoc with certain radio stations

[FredSmith]

I had one of those Belkin wireless Doohickies . In the end I bought a new stereo and etc to stream music. As you hinted in an earlier post, it would be easier to get rid of it. I kept the usb charger only.

[Cowboy Dave]

Hmm just did a test with engine off and GPS off. Still some noise there at high volumes.

Might grab these ferrite things just to prove the concept.

[Snooozy]

one way we used to work out where noise was coming from in the past was

with the engine running listen to the noise

shut off the engine, if noise continues during engine wind down, then it's in the alternator circuit

if it cuts the noise as soon as engine is shut off, then the cause is from the ignition circuit.

this was some years back & is probably more relevant to petrol motors.

[odie602r]

It is 'normal' to a point for there to be a bit of noise at high volumes when there are aux inputs plugged in - they all generate a bit of noise.

The more loops and circuits normally the higher amplitude of the background noise.

It's only considered problematic if that noise can be audibly heard when music is playing, which is what I think you've been describing

[helicoptercow]

Hmm just did a test with engine off and GPS off. Still some noise there at high volumes.

Might grab these ferrite things just to prove the concept.

i picked up some ferrites yesterday from jaycar. The guy there agreed in principle but reckoned it probably wouldn't work, that there would be enough shielding on the wire to negate the ferrite and said i could return them thankfully, because he turned out to be right... the noise is still present.

[peterdeg]

I had horrendous noises for powered devices (tablet, laptop etc) that were connected to the rca ports in the console.
Fixed it with a ground loop isolator from Jaycar http://www.jaycar.com.au/productView.asp?ID=AA3086
And a cheap fix at only $10.

[kshep89]

Bump.

Did anyone find a solution to this? Did the ground loop isolator work?

I have a similar setup with the Belkin Bluetooth and get a whine that gets worse as the revs increase to the point I don't even use it any more. Before I had a CarCom cradle with RCA jacks and it suffered the same issue. Now I have a Smoothtalker cradle and this Bluetooth setup into the back of the head unit so there's power for the Belkin, the iPhone cradle and the UHF all in there... No wonder it has issues.

Or should I just cut my losses and install an aftermarket headunit that streams bluetooth / has an ipod connector. I can plug a USB Lightning cable into the cradle and then a headunit. This might be the go.

Cheers,