Humming Noise After Amplifier Install

[jamesk]

I would bet it is the head unit (infinity), I sent mine back to infinity for this reason. They sent it back to me, tech said turn down gains on amp....I already tried that. Infinity finally told me that their head units just make noise and so do their competitors ( I don't agree with that statement). Told me I would not hear the hiss when the music plays ( which I don't) but I hear it when the music pauses or changes songs and it still bugs me since I spent the time and money putting in an amp and changing the speakers. Honestly that stock head unit sucks, it has no volume knob and is a pain in the butt to use IMO.

 

[jamesk]

Yes. The battery switch makes no difference in the noise.

He was asking about the buzzer making noise....there are two issues that may or may not be related that some of us are having....The buzzer that is located near the head unit inside....makes a constant buzzing sound ( not loud but annoying).
The other issue is noise through the speakers ( hiss) that I believe is from the head unit.

 

[Mainah]

There does seem to be an issue with some of the the 2017 21 footers and gremlins in the electrical system. The buzzer should not buzz constantly. Could be lots of things from a firmware issue such as not setting the default state of a digital output pin and it floating back and forth between states to a voltage leak somewhere. Regardless of root cause the stereo could certainly be impacted. Just one channel being impacted because of a dirty power loop is unlikely though.

 

[jamesk]

Just FYI, both my head unit and amp are each wired (+/-) directly to 1 of my batteries.

 

[Mainah]

Just FYI, both my head unit and amp are each wired (+/-) directly to 1 of my batteries.

Did you try completely isolating the audio system? Basically disconnect everything else from the power source (battery) so only the amps and head unit are connected to it with the remote turn ons jumped over to the constant 12v. Of course some audio stuff is noisy when paused and particularly on bluetooth but never a bad idea to make sure the source of the noise is not something else connected to the same power source.

 

[jamesk]

Yes I had everything disconnected except the head unit and amp and on an sx210/ ar there are no remotes to deal with.

 

[Dave burke]

Many thanks for the ideas @Mainah and @jamesk. I’ll definitely change the ground for the HU and 420 to the distribution block tomorrow. Today I moved the soundbar to the two rear channels of the amp and there’s no static. Then I connected up the swim platform speakers to the two front channels and the noise was on the same right channel. At least it’s now in the very back of the boat and not in the tower...

I disconnected the RCAs to the front channels and the noise remained. Can I therefore conclude that the problem is NOT the speaker wire since the noise remained whether the offending channel is connected to the soundbar or the swim platform speaker?

Another thought - is it possible that the amp turn on wire could be a factor? Without the RCAs connected, the only link between the HU and the amp is that wire.

I’ll provide an update tomorrow after doing the two things @Mainah suggests.

I don’t have the problem with the buzzer you mention @jamesk. What’s interesting though is when I was having problems with Can-bus loss of gauges issue earlier this year, I noticed that the wire to the buzzer had been cut. I bought the boat new so it must have been cut during manufacturing or by the dealer. The dealer (not the same one) who solved my can-bus problem (it was a bad port tach) reconnected the buzzer and it goes off for a few seconds on start up but otherwise is not a problem.

Also, FYI my HU is a Polk, not Infinity. It’s not the greatest unit either.

 

[Mainah]

Many thanks for the ideas @Mainah and @jamesk. I’ll definitely change the ground for the HU and 420 to the distribution block tomorrow. Today I moved the soundbar to the two rear channels of the amp and there’s no static. Then I connected up the swim platform speakers to the two front channels and the noise was on the same right channel. At least it’s now in the very back of the boat and not in the tower...

I disconnected the RCAs to the front channels and the noise remained. Can I therefore conclude that the problem is NOT the speaker wire since the noise remained whether the offending channel is connected to the soundbar or the swim platform speaker?

Another thought - is it possible that the amp turn on wire could be a factor? Without the RCAs connected, the only link between the HU and the amp is that wire.

I’ll provide an update tomorrow after doing the two things @Mainah suggests.

I don’t have the problem with the buzzer you mention @jamesk. What’s interesting though is when I was having problems with Can-bus loss of gauges issue earlier this year, I noticed that the wire to the buzzer had been cut. I bought the boat new so it must have been cut during manufacturing or by the dealer. The dealer (not the same one) who solved my can-bus problem (it was a bad port tach) reconnected the buzzer and it goes off for a few seconds on start up but otherwise is not a problem.

Also, FYI my HU is a Polk, not Infinity. It’s not the greatest unit either.

The diagnostics would indicate most likely an amp issue for that one channel at this point. Common path to ground may help with it some but more likely an issue with a channel specific amp board component. As stated at least on the swim deck speakers now.

 

[Dave burke]

Thanks @Mainah. I did move the ground for the HU and the WS 420 to the distribution block and the noise is still there. So I think you’re right that it’s most likely the amp.

Is it common for amps to be defective? Pretty weird that I have 3 Polk amps and am having problems with 2 of them. The 5-channel one has a bad rear channel which I don’t need but still...

 

[Bass Ho]

The fun loving hummmmmmmm is definitely from the Infinity head unit itself. JamesK hit the nail on the head, Infinity will even admit they hum. I have the PRV450 and from day one had this issue. I used to do sound installs professionally, trust me, the humming noise you are hearing is from your Infinity head unit. I have done everything humanly possible to eliminate it, even filters, plain and simple, it's the unit. If you want to eliminate the noise go spend another $350-400 for a different brand.