White/static noise help


Dbraves8

CarAudio.com Newbie
Mar 6, 2021
8
0
Cape coral Florida
I've got this static/white/floor noise on a fusion 4 channel marine amp on 4 kicker 8s. Not sure what to do. This is in a boat.

I've got ground less than 18 inches from amp to battery. Ground from radio to amp ground. Rcas are separated from power and ground runs. Backing gains down helped a little but to eliminate it then I'd need my gains at zero essentially. Im using 35 out of 40 on max volume for headunit and setting them with a 1khz test tone at 24.5 volts. 150rms at 4 ohms. I tried doing it using 30 max volume but then I had to use more gain and got more noise from speakers.

My ground from radio was at 2 different places and it didn't change anything. I moved rcas away from all the other wires. It does not get louder with volume just constantly stays the same.

Tested switching input from radio rcas to using a 3.5mm to rcas for sending signal from phone or BT adapter straight to amp. Noise pretty much gone vs running signal from radio rcas. So I'm guessing issue with rcas from radio??
 

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Buck

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Also what's most reliable source/website for test tones. I've found several but they vary greatly.
If you have a PC, get audacity and make your own test tones.
 

Buck

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Just want to get this noise figured out first.
Oh I got you. Is the battery in your boat that everything is connected to, is that the main battery for the whole boat?
 

Dbraves8

CarAudio.com Newbie
Mar 6, 2021
8
0
Cape coral Florida
  • Thread Starter Thread Starter
  • #9
Oh I got you. Is the battery in your boat that everything is connected to, is that the main battery for the whole boat?
Yes its the main battery that runs everything. The headunit Rockford Fosgate RFXMR5BB Marine Wired Remote for RFX3000 which is the hideaway unit.
 

Buck

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Yes its the main battery that runs everything. The headunit Rockford Fosgate RFXMR5BB Marine Wired Remote for RFX3000 which is the hideaway unit.
How is the radio and everything wired? Is it wired into where other electronic components are wired? Like sharing the same terminals?

And how long has this been going on? Always or did it not used to make static noise?
 

Dbraves8

CarAudio.com Newbie
Mar 6, 2021
8
0
Cape coral Florida
  • Thread Starter Thread Starter
  • #11
How is the radio and everything wired? Is it wired into where other electronic components are wired? Like sharing the same terminals?

And how long has this been going on? Always or did it not used to make static noise?
Everything is sharing except amp is straight off the battery. It never was like this when using headunit only prior to running amps.
 

Dbraves8

CarAudio.com Newbie
Mar 6, 2021
8
0
Cape coral Florida
  • Thread Starter Thread Starter
  • #12
How is the radio and everything wired? Is it wired into where other electronic components are wired? Like sharing the same terminals?

And how long has this been going on? Always or did it not used to make static noise?
I tested pre out voltage at max 40 out of 40 volume im seeing about 2 volts. On 35 out of 40 only seeing about 1 volt. Thinking voltage from preouts are so low im compensating on the amp getting floor noise? 2 volt reading was from testing just one single rca preout.
 

Buck

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I tested pre out voltage at max 40 out of 40 volume im seeing about 2 volts. On 35 out of 40 only seeing about 1 volt. Thinking voltage from preouts are so low im compensating on the amp getting floor noise? 2 volt reading was from testing just one single rca preout.
You could have to turn your amp gains up so much that you're getting noise. I always recommend a 4v+ pre-out radio. 2v are almost useless.
 

GTSQ

CarAudio.com Recruit
Jun 28, 2020
80
32
Idaho
I did everything but drive my truck off a cliff to get rid of my noise. Turned out to be a bad amp.
Double/triple check that grounds are solid with no corrosion. It could be anything from CB antenna to crappy RCAs. There is no logic in diagnosing electrical gremlins.
Here is a link to a checklist. It may help but don’t take it as gospel. Trial and error .....over and over again. I can guarantee you this,it’ll sound great when you fix it!

 

Dbraves8

CarAudio.com Newbie
Mar 6, 2021
8
0
Cape coral Florida
  • Thread Starter Thread Starter
  • #16
You could have to turn your amp gains up so much that you're getting noise. I always recommend a 4v+ pre-out radio. 2v are almost useless.
I think thsts the problem. They are rated at 3volts but I only see 2 volts at max volume. Im worried I have clipping from headunit with max volume. Im using 35/40 and seeing 1.2 volts or so. I tested the theory of 10k hz tone and at 25rms per channel from headunit I get 10 volts. So I'm guessing 35 is max before distortion. I ordered 2 pac ground loop isolators to see if thst fixes the issue. I think its floor noise because at 35/40 and gains backed down vs 30/40 with gains up more the noise was louder and more obvious. If those don't do the trick then a equalizer with built in line driver will be next. Its just weird how when using the 3.5mm to rcas and bypassing the radio the noise diminished greatly.
 

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