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Help! Motor noise through speakers!

Old 07-15-2011, 01:09 PM
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Default Help! Motor noise through speakers!

I'm usually pretty good at figuring these things out but I'm stumped on this one.

The system.....

Fusion IP600
JL Audio 900/5 amp
JL Audio 7.7 components X4
JL Audio 10" subs X2

I can hear everything through the speakers. I get a "zzzzzip" noise in the speakers when I start the engines. I can hear clicking when I hit the trim tabs and engine trim and the most annoying noise that is about to make me pull my hair out is a high pitch whistle noise through the speakers but only when the port engine goes past 1500 RPMs.

I have already moved the radio power and ground all over the place and no change. The amp is powered by the port battery. I am thinking the problem lies with the amp on this one?

Short of installing a complete 12 volt system just for the stereo and amp not connected to the boats electrical system I am out of ideas.
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Old 07-15-2011, 01:38 PM
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Google alternator noise filter & Amplifier noise.
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Old 07-15-2011, 01:45 PM
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Forgot to add...

When I hear the high pitch whistle through the speakers. If I hit the trim tabs or engine tril the noise stops. Also if I turn on a bunch of accessories like lights, GPS, ect it will stop.
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Old 07-15-2011, 02:13 PM
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Originally Posted by ScarabChris View Post
Forgot to add...

When I hear the high pitch whistle through the speakers. If I hit the trim tabs or engine tril the noise stops. Also if I turn on a bunch of accessories like lights, GPS, ect it will stop.
There's nothing wron with your amp, it amplifies the signal it gets. The noise is on your DC system and when you put a big load on it, you are shorting the noise signal to ground.

First, unplug the head from the amp. Still get the noise or not?
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Old 07-15-2011, 02:15 PM
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Originally Posted by ScarabChris View Post
.......the most annoying noise that is about to make me pull my hair out is a high pitch whistle noise through the speakers but only when the port engine goes past 1500 RPMs.
If the noise is only when the port engine is running over 1500 RPM, the problem is with the engine, not your sound system.
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Old 07-15-2011, 02:25 PM
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OK I have narrowed a few things down. There are two separate issues. The "zzzzzip" when I start the engines and the noise from the trim tilt do not seem to be related to the high pitch whistle.

I disconnected the RCA from the amp and I still get the high pitch whistle. But I noticed it is on both engines. I just only noticed the noise from the port because the stbd takes a little more RPM to produce the noise.

I doubt its a problem with two pretty new engines with 200 hours on them. I had the same exact engines on my last boat and the same exact system (different amp) and zero noise.

This is definitely an amp to battery issue, has to be. The battery the amp is connected to is brand new, the wiring is brand new and the amp is brand new.

I'll have to do some more digging.

Aside from the noises the system sounds great.
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Old 07-15-2011, 03:07 PM
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Try this. Go to an auto radio shop and ask for a noise filtering capacitor. Connect it between the positive and negative conductors where your amp receives power. See if that helps. They might have other ideas as well.
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Old 07-15-2011, 03:12 PM
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I was able to greatly reduce the noise by turning the input sensitivity down. But this also reduces the output capabilities of the amp.

I'll have to try the filter.
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Old 07-15-2011, 03:40 PM
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Originally Posted by ScarabChris View Post
I was able to greatly reduce the noise by turning the input sensitivity down. But this also reduces the output capabilities of the amp.

I'll have to try the filter.
Is the amplifier chassis grounded?
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Old 07-15-2011, 03:55 PM
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What if both the power and the return for your sound system components are moved from the existing location to right onto the battery?

Does that fix the problems?
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Old 07-15-2011, 05:25 PM
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Originally Posted by rwidman View Post
Is the amplifier chassis grounded?
Originally Posted by wingless View Post
What if both the power and the return for your sound system components are moved from the existing location to right onto the battery?

Does that fix the problems?
The amp is bolted to the inside of the console. The positive and negative are supplied via 6 gauge cables going directly to the battery. The power for the head unit is supplied by a power block that is connected to the same battery as the amp but it runs through the battery switch.


My next step was going to be to run power directly from the battery to the head unit so it bypasses the boats battery switch.
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Old 07-15-2011, 05:46 PM
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Ground loop Isolator. Check where your wire is run near all of them. Mhd are super sensitive
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Old 07-15-2011, 05:48 PM
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Originally Posted by ScarabChris View Post
The amp is bolted to the inside of the console. The positive and negative are supplied via 6 gauge cables going directly to the battery. The power for the head unit is supplied by a power block that is connected to the same battery as the amp but it runs through the battery switch.


My next step was going to be to run power directly from the battery to the head unit so it bypasses the boats battery switch.
If you unplugged the audio cables from the power amp (at the amp end) and still have the noise you don't need to worry about the head unit. Or the cables.

You shouldn't have electrical noise coming from the engines. Do you have resistor spark plugs? Is it the alternator, not ignition noise? If so, you can put a filter capacitor on the alternator.
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Old 07-16-2011, 06:02 AM
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Yes when I unplug the RCA cables from the amp I still get the high pitch whistle after 1500 RPMs. But I do not get all the other sounds like the zzzzip from starting the engines and clicking from the trim/tilt. So I do have two separate issues.

I have twin 250 E-Tecs, there is no traditional alternator. Its a standard magneto type charging system. The plugs are specific to the engines. No way to switch plugs. But like I said I had the same engines on the last boat and no noise.

I think I will try to run the power for the head unit directly to the battery where the amp is connected and see what happens. I can run it over the deck just to test before I go through the trouble of pulling wire.
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Old 07-16-2011, 08:43 AM
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Chris,
I had a background noise on my system, although not as bad as yours sounds like, that was remedied by connecting the "-" of all 4 batteries together to essentially create a single ground for the entire boat. When the noise was present, I had the 2 starter batteries grounded together and the 2 house batteries grounded together. Now, I added a ground strap (2 gauge) between the engine batteries and the house batteries.
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Old 07-16-2011, 11:52 AM
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Originally Posted by RUDE Attitude View Post
Chris,
I had a background noise on my system, although not as bad as yours sounds like, that was remedied by connecting the "-" of all 4 batteries together to essentially create a single ground for the entire boat. When the noise was present, I had the 2 starter batteries grounded together and the 2 house batteries grounded together. Now, I added a ground strap (2 gauge) between the engine batteries and the house batteries.
On a boat, there is a single ground (negative) already.
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Old 07-17-2011, 02:10 PM
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Originally Posted by RUDE Attitude View Post
Chris,
I had a background noise on my system, although not as bad as yours sounds like, that was remedied by connecting the "-" of all 4 batteries together to essentially create a single ground for the entire boat. When the noise was present, I had the 2 starter batteries grounded together and the 2 house batteries grounded together. Now, I added a ground strap (2 gauge) between the engine batteries and the house batteries.
Interesting, I'll check that out.
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Old 08-09-2012, 12:30 PM
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OK this is an old thread but I just gave up last year but it has gotten to me. Basically the noise is coming though the amp power cable. If I switch the battery switches (2 engines, 2 switches and 2 batteries) so the engines are not charging the battery the amp is hooked to the noise disappears.

So basically the amp is on battery #1 which is also the port engine. If I move both switches to #2 the noise goes away. But now the engines are only charging battery #2 and the one the amp is drawing off isn't charging.

If I move both switches to ALL then the noise happens with both engines.

I think I will need to find some kind of heavy duty noise filter for the amp power line. But until then I know how to eliminate the noise when running. And you can only hear it when idling anyway.
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Old 08-09-2012, 12:48 PM
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Have you checked all of the connections on Battery 1, including how the ends are crimped onto the cables? If this only showed up after the new engines were installed I would have to imagine it was something to do with the installation, even if it was inadvertent. Have you tried physically swapping battery 1 with battery 2, or swapping the amp power cable from bat1 to bat2?
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Old 08-09-2012, 01:25 PM
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Everything is good in the connections. Actually there are 4 batteries but they are wired in pairs so its like 2 big batteries. The boat came with the engines but no sound system, not one with an amp anyway.

My theory is that maybe after a certain RPMs these engines generate a little more power than normal. Maybe that's why the noise only shows up once the engines hit 1200 or so RPMs.

Strange.....like I said I had the same engines and sound system on my last boat but didn't have this noise. Obviously it's something in the boat's wiring but I'm not about to start tearing into that. I'll just deal with it then try to find a heavy gauge noise filter for the amp power lead.
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