Radio won't work correctly when engine is on

[Formula001]

Last summer I totally revamped my boats electrical. I also installed a battery selector switch. I am running 2 battery's with one being a deep cycle for lights and the radio. Now I am running a pretty big system with 2 amps, 2 subwoofers and 4 speakers. Problem is that when the boat is running and I turn on the radio it makes a horrible screeching sound, but when the boat is off it all works flawless. Needless to say last summer I could only listen to the radio while the motor was off. This year I am trying to come up with a solution. All input will be appreciated thanks.

 

[Bondo]

Re: Radio won't work correctly when engine is on

Problem is that when the boat is running and I turn on the radio it makes a horrible screeching sound, but when the boat is off it all works flawless.

Ayuh,.... Welcome Aboard,.... I'd have to think yer gettin' interference from the alternator,...

The Electrial Gurus are gonna want to know Exactly how you've got it wired up...

 

[Scott Danforth]

Re: Radio won't work correctly when engine is on

I would say your either picking up ignition noise or you have a rectifier going on the alternator.

 

[Formula001]

Re: Radio won't work correctly when engine is on

I would say your either picking up ignition noise or you have a rectifier going on the alternator.

How would you suggest I go about fixing this. Would I need some kind of suppressor to filter the noise or is it a problem with my ignition?

 

[mark1905]

Re: Radio won't work correctly when engine is on

Sounds like you have a ground loop. Read up on it here: http://www.termpro.com/asp/pubs.asp?ID=121

There could be several problems causing this, but the most common is insufficient wiring. If you're using wire that is too small of gauge or is corroded, you'll run into this problem. It's especially prevalent on a boat when standard car audio power wire was originally used to wire things up and the soft copper starts degrading.

What gauge cable are you using for your power and ground? Marine or non? How are you wiring it?

Things should be as straight forward and as direct as possible. Depending on the size of the amp and length of wire, 4-8 AWG marine cable should be used. Amps should be grounded straight to the battery. +12V either straight from your switch or straight from the battery. If going through the switch, make sure that the cable feeding the switch is at least 1 AWG. Over-do and over-design all of your electrical system, and you'll have a much better time with things.

For my 6 amps (yeah.. 6. Don't ask ).. I use 2 batteries and special 3 x 1 AWG battery terminals on all 4 posts, run 1 AWG to 4 distribution blocks that split it into 4 AWG cables for all amps. 1 AWG cable to and from the alternator both for the charging cable and the ground. 1 AWG ground wire to the motor. 2 AWG for the main starter cable. 1 AWG between the batteries. ALL marine grade, nothing but.

She sounds.. alright..

 

[Formula001]

Re: Radio won't work correctly when engine is on

Yeah I'll try what was mentioned. But I suspect it is my grounds. I grounded with 8AWG non marine. Why would the ground only effect it when it's started? I just figured since it worked when the engine was off they were fine. Also im not sure if this matters but when i turn the radio on with the engine on there is no song playing just all screetchig.I guess this is why I'm not an electrician.

 

[mark1905]

Re: Radio won't work correctly when engine is on

Yeah.. you have a ground loop. Classic case. It's not just the ground cable that needs to be perfect though, but both of them. Check every single inch of every connection.. at the amp itself, at the battery, etc etc. Use power distribution blocks to split that power up, too. I would be running one master 4 AWG cable for both the +12V and GND straight off the battery into two fused distribution blocks that split it to 8 AWG.

You're going to have a tough time with that non-marine cable, trust me. My boat never sees salt water, is always covered when not in use.. and still.. that soft non-marine copper wire will be worthless within a years time.. and what's worse is you may not find out until you fry your amp and/or your speakers because you're choking it for power. I learned the hard way and thankfully only mid-way through my year long sequential installation of a bigger and bigger system.

Curious.. since you're running two amps.. is the noise in all speakers? Have you tried isolating the noise to one amp by disconnecting one or the other? That could help you narrow down the issue. What brand/type of amp are you running?

 

[bruceb58]

Re: Radio won't work correctly when engine is on

Its not a ground loop and its not your wiring gauge. If it was either of those you would have problems with the engine off.

Get a multimeter and set it to measure AC and measure the voltage of your alternator output to the alternator case. Should be less than 0.5V.

 

[mark1905]

Re: Radio won't work correctly when engine is on

Its not a ground loop and its not your wiring gauge. If it was either of those you would have problems with the engine off.

Let me be more specific then.

"Alternator whine"

..or more commonly known/referred/blamed on in the mobile audio world as "ground loop".

 

[bruceb58]

Re: Radio won't work correctly when engine is on

Let me be more specific then.

"Alternator whine"

..or more commonly known/referred/blamed on in the mobile audio world as "ground loop".

I am an EE, and trust me, alternator whine is not "ground loop".

He needs to isolate what is causing the noise first and correct if he can. Bigger cabling won't help. Marine cable won't help. Finer strand cable won't help.

He first needs to isolate it between alternator and ignition system but checking the voltage ripple of the alternator is really easy. I like the previous suggestion of running with the alternator belt off to make sure it isn't something else like a fuel pump, blower...

 

[mark1905]

Re: Radio won't work correctly when engine is on

I am an EE, and trust me, alternator whine is not "ground loop".

You are correct, sir. It's a common misnomer that's used very frequently.

 

[bruceb58]

Re: Radio won't work correctly when engine is on

You are correct, sir. It's a common misnomer that's used very frequently.

Then why are you calling it a "classic case of ground loop"?

Another thing that needs to occur is if its radiated noise into signal lines or coming through the power. I would run the stereo from a "stand alone" battery with the engine on. If there is noise in that situation, that is going to be a tougher situation to correct because its radiated noise and signal wire routing would be culprits.

Curious if there is still noise with the inputs to the amps disconnected. That would at least isolate the noise to the amplifier section or the stereo side.

In any case, the OP has a few things to try.

 

[mark1905]

Re: Radio won't work correctly when engine is on

:facepalm:

 

[Formula001]

Re: Radio won't work correctly when engine is on

Well I guess I'll have to wait until this weather finally breaks and I can de-winteriz and get it started up to try without the belt on. One question I do have now is why if the grounds are bad would it work fine with the engine off? I just don't understand that.

 

[bruceb58]

Re: Radio won't work correctly when engine is on

One question I do have now is why if the grounds are bad would it work fine with the engine off? I just don't understand that.

I don't either.

You could have poorly routed power/ground that gets close to an offending noise producer. Do the other tests first though.

 

[mark1905]

Re: Radio won't work correctly when engine is on

I don't either.

Exactly my point

An "EE" you may be.. but that doesn't automatically qualify your knowledge with audio systems.


"The biggest offender of noise in the car audio environment is alternator whine. Alternator whine is caused by a difference in electrical potential (voltage) between two points. It's usually caused by a ground connection that is less than ideal. The main culprits are the amp, the head unit and any intermediate components such as crossovers and equalizers. Basically any component that touches the low level music signal (from RCA cables). It's usually cured by finding the source of the noise entrance and re-grounding that component."

http://www.caraudiohelp.com/newsletter/alternator_whine.htm

The reason why you don't hear the whine when the engine is off is because the alternator is not spinning and creating electrical "noise" in the system.

"Finally the most famous culpret... The Ground Loop.

In electrical engineering and electronics, a ground loop refers to an unwanted current that flows in a conductor connecting two points that are nominally at the same potential, for example ground potential, but are actually at different potentials. In english, this means that one component has found it easier to ground itself through another component.

Remember in the beginning when I spoke about grounds and making them as clean and efficient as possible? Well this is where its important. If a component does NOT have a proper ground, it will look to ground itself through the easiest means. This is by grounding through the next component down the line. How does it do this? Through those nifty RCA cables. The outer shielding of the RCA cables is actually a common ground (in most cases). If your PC's ground is not so great, it will try to ground itself through your amplifier's ground by passing its ground through the RCAs and into the amp. This is where all that noise comes from. This can happen if the ground potential of any one component is higher/lower than another. We combat this by making sure our ground are sufficient (first paragraph). "

http://www.mp3car.com/car-audio-faq/79248-induced-noise-ground-loop-trouble-shooting-guide.html

Remember back when I suggested to play with the RCA cables to try and isolate the problem? How about checking the grounds? Both of these are the reasons for all of that. Which reminds me.. check the ground of your head unit, too. Ideally it should be grounded straight to the battery even though you're not using the internal amp. RCA cables are also suspect. If your amps are next to each other, use one high quality cable to stretch to one, and then a shorter but equally as high quality cable to loop from the line out to the line in on the second amp. The less length of RCA cables that you have running around the place, the better.


But hey.. whom am I? I'm no "EE".. but I've been professionally installing both car and boat audio systems for 21 years.


Have fun!

 

[bruceb58]

Re: Radio won't work correctly when engine is on

But hey.. whom am I? I'm no "EE".. but I've been professionally installing both car and boat audio systems for 21 years!

LOL...that explains everything!

By the way, don't believe everything you read in these articles. You may think these guys know what they are talking about but they don't. They are one step away from being the sales guy at Best Buy that barely squeaked through high school.

Don't get me wrong, a bad ground can introduce all sorts of problems and is why I usually homerun the power to the battery.

The OP has a lot of homework to do before he/we can diagnose from a blogsite.

An "EE" you may be.. but that doesn't automatically qualify your knowledge with audio systems.

I guess years of working on Radar Signal Processing wouldn't count where the accuracy of the low level signals blow away anything required by an audio system. Amazes me when the audio guys start talking about braided speaker wire, skin effects and a bunch of other nonsense that a human can't even hear.

 

[Formula001]

Re: Radio won't work correctly when engine is on

Well it finally warmed up around here and I had some time to start the boat up. I disconnected the alternator belt and that did help it some. I can actually play music and hear it now. BUT theres always a but, there is still a popping\clicking noise that I can hear. It still works perfectly when the boat is not running. Would this be the ignition? I am going to swap the plugs out in a few days.

 

[mark1905]

Re: Radio won't work correctly when engine is on

This thread is hilarious.. I had forgotten all about it. Momma taught me to never get in a stupid war with those more stupid than I because.. well.. guess what? They'll win every time.


Anyway..



If you've made extra sure that your grounds are completely kosher, clean, direct and sufficient.. then honestly the only weak link left is the amplifier itself. Either a cheap amp or even the best of the best can start to give you issues when the corrosion builds internally. If you've checked all there is to check externally and you're still getting the noise.. then most likely it's the amp itself. All you can do is to make SURE that your grounds are grounded with the correct cable, your RCAs are good quality.. and that all your i's are dotted and your t's crossed.

One thing you may try as a last ditch is to ground your RCA cables. Take a piece of scrap wire and strip down the end to a couple inches of bare wire. Wrap it around the outside female connectors on the RCA cable. Sandwich it in between the male and female as you plug them back together. Connect the other side to the GND post on the battery. Fire the system up. Any help? Sometimes, you'll get a nice little loop of electricity finding it's way to the easiest ground through your cables and giving you some line level noise which gets amplified through your speakers. It's worth a shot.


If all of the above fails to solve it, dollars to donuts.. it's your amp itself.



Now.. be a dear and pass grandpa the clicker.. Wheel of Fortune is over.. and dammit.. Vanna isn't getting any younger..

 

[bruceb58]

Re: Radio won't work correctly when engine is on

Well it finally warmed up around here and I had some time to start the boat up. I disconnected the alternator belt and that did help it some. I can actually play music and hear it now. BUT theres always a but, there is still a popping\clicking noise that I can hear. It still works perfectly when the boat is not running. Would this be the ignition? I am going to swap the plugs out in a few days.

So did you try measuring the ripple voltage of your alternator as I suggested earlier?

You also have no idea if its your head unit or your amplifier that is picking up the noise. You can easily isolate this by creating grounding plugs for the inputs of the amps. If you still get noise, then you know its from the amp.

Improperly gapped plugs(too wide) can add to ignition noise. What happens is that if the gap is too wide the energy that has built up in the coil has to go somewhere and that somewhere can be the coil tower or spark plug boots/wires to ground.

You have a lot more troubleshooting to find the cause of the noise before you start resorting to band aid fixes.