Stereo system noise from using phone/dock/charger

So, I've been getting some noise when using my phone for an audio source.

I have a car dock for my phone that has a micro-usb that slides into the phone for audio and charging. The dock has a micro usb plug on the back as well as a 3.5mm outlet.

I have a 3.5mm cable (just a cheap one I had laying around) that goes from the car dock to the aux input of the WS420SQ.

I also have a car charger going into the car dock's micro usb.


I would get noise on my system (like the same kind of sound speakers make when they are getting GSM interference). So I tried unplugging the 3.5mm cable from the car dock and plugged it directly into the headphone jack of the phone. That seemed to help on last weekend's trip.

Yesterday I was getting noise in my system again and the "solution" was to unplug the car charger (which was plugged into one of the boat's 12v cig lighter style sockets).

I've heard that there's some "ground loop" stuff going on. I'm curious what's going to be the best way to address this.

I'd like to still use the car dock if possible, because it's nice to have something holding my phone as I'm driving and to still have the ability to change songs and stuff (rather than keep it inaccessible in the glovebox).

I am not opposed to hard wiring the car charger into the boat's electrical system (although I'm open to hearing the best place to tap the power for that).

I'm certainly willing to buy a different 3.5mm cable to connect my dock or phone to the WS420SQ.

Thanks for the insight.

Have you tried a different phone. In my expierence 3.5 mm jacks go bad and chase a lot noise. Especially in a boat where they take a pounding.

Originally Posted by Redheadd

Have you tried a different phone. In my expierence 3.5 mm jacks go bad and chase a lot noise. Especially in a boat where they take a pounding.

I haven't. the 3.5 cord is a short one at the helm, so if we have others plug in their phones I just have them jack in at the glove box (which is a 3.5mm input into the MB Quart Headunit).

I think it has to do with the charging cable being plugged in, because when I unplugged the charging cable's power the noise seemed to go away.

This happens often in car/boat audio. Most likely a ground loop isolator will fix it or help immensely. Here is what you need to try:

http://www.amazon.ca/PAC-Ground-Isol...+isolator+35mm

I really can't believe that after all these years they haven't figured out a better way to connect car amps. By 2015 you would think a single cat6 cable from deck to amp/amps could do EVERYTHING, all in digital, perhaps even IP based. I at least would have thought all mobile A/V communications would be digital by now. I'm sure some audio gurus will come on here and explain why Analog signals are better or why the technology doesn't work yet.

If you have no noise when listening to the phone on battery power but suddenly have noise when you add the charger then you likely have a ground loop.
Here's the issue. The EQ RCAs are 'above ground'. The audio output shield ground of the phone, once plugged into the charger, references boat ground. There's a potential inequity which promotes the flow of current. On that current rides boat noise, or charger noise, noise in the form of DC ripple. Now that noise is traveling down a ground path that was intended to shield the audio signal from noise...not transmit noise. Instead you have the fox watching the hen house.
Ground loop isolators are generally bad news. They put a bandaid on an unresolved problem. However, in this application you may not have a choice.
So here is what you can try. Convert 3.5mm over to RCA, introduce an RCA ground loop adapter, convert from RCA back to 3.5mm. See if you get an improvement.
The ground loop isolator places a small transformer on both L & R ground shields. AC passes. DC that carries the noise cannot pass.
No guarantees. Just my best guess.

Originally Posted by 501s

This happens often in audio. Most likely a ground loop isolator will fix it or help immensely. Here is what you need to try:

http://www.amazon.ca/PAC-Ground-Isol...+isolator+35mm

Great. Didn't know they had one already for 3.5mm.

Originally Posted by DavidAnalog

If you have no noise when listening to the phone on battery power but suddenly have noise when you add the charger then you likely have a ground loop.
Here's the issue. The EQ RCAs are 'above ground'. The audio output shield ground of the phone, once plugged into the charger, references boat ground. There's a potential inequity which promotes the flow of current. On that current rides boat noise, or charger noise, noise in the form of DC ripple. Now that noise is traveling down a ground path that was intended to shield the audio signal from noise...not transmit noise. Instead you have the fox watching the hen house.
Ground loop isolators are generally bad news. They put a bandaid on an unresolved problem. However, in this application you may not have a choice.
So here is what you can try. Convert 3.5mm over to RCA, introduce an RCA ground loop adapter, convert from RCA back to 3.5mm. See if you get an improvement.
The ground loop isolator places a small transformer on both L & R ground shields. AC passes. DC that carries the noise cannot pass.
No guarantees. Just my best guess.

Isn't it true that if you can get the grounds the same for the deck, the EQ, and the phone charger, then it'd be better? Like hardwiring the car charger to the boat and making sure the ground of the 420 is the same as the ground of the hardwired charger? Or am I off-base here?

I believe you would want to make sure the deck, WS420, 12 volt Car charger socket and the amps all share a common ground, but even than, sometimes there can be noise.

Originally Posted by 501s

This happens often in car/boat audio. Most likely a ground loop isolator will fix it or help immensely. Here is what you need to try:

http://www.amazon.ca/PAC-Ground-Isol...+isolator+35mm

I really can't believe that after all these years they haven't figured out a better way to connect car amps. By 2015 you would think a single cat6 cable from deck to amp/amps could do EVERYTHING, all in digital, perhaps even IP based. I at least would have thought all mobile A/V communications would be digital by now. I'm sure some audio gurus will come on here and explain why Analog signals are better or why the technology doesn't work yet.

I suppose it's worth a shot to bandaid the problem for the short term... I mean the ground loops isolators are $10 to $20.

I actually found one that's a ground loop isolator and a line driver, so I'll give that a try. Maybe solve two issues at once (the fact that the phone doesn't play as loud as other sources).

Of course I should also transfer most of my phone media to a USB drive and play it off the deck, that would also solve a lot of this.

Originally Posted by 501s

I believe you would want to make sure the deck, WS420, 12 volt Car charger socket and the amps all share a common ground, but even than, sometimes there can be noise.

yeah, that's what I was remembering. I chased down and resolved all the noise in my old Supra. I suppose in time I can chase everything down and get there with my Moomba too.

Originally Posted by trayson

Isn't it true that if you can get the grounds the same for the deck, the EQ, and the phone charger, then it'd be better? Like hardwiring the car charger to the boat and making sure the ground of the 420 is the same as the ground of the hardwired charger? Or am I off-base here?

You could have everything wired to absolute perfection with all the supply grounds and still have this noise.
Because....the audio electronics as a whole and the phone charger are not following the same scheme on their signal grounds. Supply grounds and signal grounds are two very different circuits and the joining of these two circuits related to DC are generally only intended to take place at a single point. Two such points where signal grounds reference supply grounds can be trouble...as in noise.
As an alternative you could also try grounding the 3.5mm shield at the input of the EQ (or the output of the phone, as the same difference) to the common supply ground. The noise could get worse or it could go away.

Originally Posted by trayson

Isn't it true that if you can get the grounds the same for the deck, the EQ, and the phone charger, then it'd be better? Like hardwiring the car charger to the boat and making sure the ground of the 420 is the same as the ground of the hardwired charger? Or am I off-base here?

Yes, it would be better. Make sure the amps/deck/eq/cigarette charger are to the same grounding point. You can help eliminate ground noise like that by putting both grounds at the same potential. With them grounded at different points and going through who knows however many different wires with other things connected to them, you get a different resistance, and possibly some other electrical noise in that as well. Putting them at the same ground can definitely help. This is why (along with remote turn on) that a lot of RCAs made for mobile applications have a ground wire between the pairs, so you are able to put the components at a common grounding potential. It may not be the silver bullet as there could be other things going on, but it sure could help things out, if not eliminate the problem all together.

Come to think of it, I had an 08 XLV, and I had the exact bad ground looping right from the factory. The first week I had the new boat, I threw in an isolator alike the one above and never had one problem after that.

I was always surprised a company would let their boats leave the factory with ground loop noise.