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Help! Motor noise through speakers!

Old 08-09-2012, 03:01 PM
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Have you called JL? I know they had an advisory about MHd amps and trim tabs a while back. I have not experienced the problems myself but have had people tell me about MHD amps and noise issues.
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Old 08-09-2012, 03:01 PM
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Take ur amp positive straight to one of ur battery switch commons. Negative straight to a battery. Take the negative from ur head unit and stick it in the negative on ur amp. Take the positive and put it to the power side of ur amp breaker with its own fuse.
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Old 08-10-2012, 06:45 AM
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Originally Posted by MB Marine Electronics View Post
Have you called JL? I know they had an advisory about MHd amps and trim tabs a while back. I have not experienced the problems myself but have had people tell me about MHD amps and noise issues.
I never even thought it could be the amp itself. Is that bulletin posted online somewhere?

Originally Posted by bradv View Post
Take ur amp positive straight to one of ur battery switch commons. Negative straight to a battery. Take the negative from ur head unit and stick it in the negative on ur amp. Take the positive and put it to the power side of ur amp breaker with its own fuse.
For some reason that makes sense to me. It would be easy enough to do so I will try it and report back.
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Old 08-10-2012, 11:22 AM
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Do you have a negative connecting battery 1 and 2 together.
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Old 08-10-2012, 01:14 PM
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That's exactly how I have mine wired with a ra 200 and 3 mhds. No noise from anything. That way u know the power is clean to both the amps and head unit and they are using the same ground so no loops.
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Old 08-10-2012, 01:45 PM
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Originally Posted by ScarabChris View Post
I never even thought it could be the amp itself. Is that bulletin posted online somewhere?.
I tried but couldnt find it online. I would try calling them directly.
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Old 08-10-2012, 02:33 PM
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The Etec's put out a max of 50 amps of charge.

Instead of having two starting batteries for each engine (2 banks), you could pretty easily go to 3 banks. 1 battery per engine, and 2 isolated batteries in parallel for house loads. It seems like the charging load is finding it's way into your amp somehow (technical term ) from what you are saying about the noise going away when you switch the charge off to that bank.

Also, how are your batteries wired? Etecs have an "Auxiliary Battery Charge Isolator" capabilty. You use the "Accessory Charge Lead Kit" (p/n 5006253). I've got my '06 service manual open to that page right now (pg #38).

It shows these kits used in the proper wiring diagram even for when you have two starting batteries for each engine. There is a connector on the engine that the kit plugs into. It basically splits the 50 amp charge into 2 x 25 amps, so each engine will independently charge either two batteries or two banks. It does away w/ the need for a voltage sensing relay between your engine & house battery to insure the engine always gets charged 1st.

It sounds like your two batteries for each bank might be wired in parallel though, so acting like one big battery for each engine. Maybe someone smarter than me can take a shot at why 50amps going into 2 batteries in parallel could find its way into your amp wired to the same battery. Something makes me think it's excess juice, & the sounds goes away when you hit your trim or tabs switch b/c they are hi load & consume that juice.

Again, I only know enough to get myself into trouble - which is why I have been studying the manual in prep for rewiring my batteries this weekend for my new etecs.

Ideally, your house loads are on an isloated battery(s) to begin with. I can't say why (again sure someone smarter can) this would change your noise issue, but that's where the logic is telling me your problem lays. It's also just good practice to have your starting batteries independent of a non-essential (blasphemy I know) component like an amp.

The kits are a hundred something each. Maybe you already have them, but I would look at reconfiguring your battery system to isolate the house loads. It won't take much if you already have 4 batteries & the two switches. That's my best guess & 2 cents worth at least.
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Old 08-10-2012, 02:47 PM
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Originally Posted by bradv View Post
Take ur amp positive straight to one of ur battery switch commons. Negative straight to a battery. Take the negative from ur head unit and stick it in the negative on ur amp. Take the positive and put it to the power side of ur amp breaker with its own fuse.

Do this....solves a lot of looping issues!!! Always my first try and it knocks out the noise a large percentage of the time on most installs!
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Old 08-10-2012, 02:51 PM
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Originally Posted by jonnysteals View Post
Do you have a negative connecting battery 1 and 2 together.
Yes there is a ground cable connecting bank 1 and bank 2

Originally Posted by kitebuz View Post
The Etec's put out a max of 50 amps of charge.

Instead of having two starting batteries for each engine (2 banks), you could pretty easily go to 3 banks. 1 battery per engine, and 2 isolated batteries in parallel for house loads. It seems like the charging load is finding it's way into your amp somehow (technical term ) from what you are saying about the noise going away when you switch the charge off to that bank.

Also, how are your batteries wired? Etecs have an "Auxiliary Battery Charge Isolator" capabilty. You use the "Accessory Charge Lead Kit" (p/n 5006253). I've got my '06 service manual open to that page right now (pg #38).

It shows these kits used in the proper wiring diagram even for when you have two starting batteries for each engine. There is a connector on the engine that the kit plugs into. It basically splits the 50 amp charge into 2 x 25 amps, so each engine will independently charge either two batteries or two banks. It does away w/ the need for a voltage sensing relay between your engine & house battery to insure the engine always gets charged 1st.

It sounds like your two batteries for each bank might be wired in parallel though, so acting like one big battery for each engine. Maybe someone smarter than me can take a shot at why 50amps going into 2 batteries in parallel could find its way into your amp wired to the same battery. Something makes me think it's excess juice, & the sounds goes away when you hit your trim or tabs switch b/c they are hi load & consume that juice.

Again, I only know enough to get myself into trouble - which is why I have been studying the manual in prep for rewiring my batteries this weekend for my new etecs.

Ideally, your house loads are on an isloated battery(s) to begin with. I can't say why (again sure someone smarter can) this would change your noise issue, but that's where the logic is telling me your problem lays. It's also just good practice to have your starting batteries independent of a non-essential (blasphemy I know) component like an amp.

The kits are a hundred something each. Maybe you already have them, but I would look at reconfiguring your battery system to isolate the house loads. It won't take much if you already have 4 batteries & the two switches. That's my best guess & 2 cents worth at least.
Yes 4 batteries total making 2 banks. Each bank has 2 batteries wired to act like one large battery.

I'll investigate your theory on the aux charging on the engines. But I do agree that the excess juice from the engines charging system is causing it.

But in the spirit of keeping it simple I have ordered a heavy duty 40 amp noise filter for the amp power cable and I will wire it as bradv explained. Trying these together will take all of 15 minutes.

It has just been raining most of the day so I haven't had a chance to go out and do it. Plus I want to wait for the noise filter to come in so I can do that at the same time.

Thanks for all the tips guys, I will report back with the results.
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Old 08-31-2012, 09:51 AM
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I finally had some time to tinker with this issue today. I installed that heavy duty noise filter and it did absolutely nothing! This afternoon I am going to wire it up like bradv described. Hope that does it.
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Old 08-31-2012, 01:14 PM
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Originally Posted by bradv View Post
Take ur amp positive straight to one of ur battery switch commons. Negative straight to a battery. Take the negative from ur head unit and stick it in the negative on ur amp. Take the positive and put it to the power side of ur amp breaker with its own fuse.
Dude you're my f-ing hero!

OK so here is was I was dealing with. The system had two separate noises. One was the high pitch whistle once the engine RPM's went past 1200-1500. This was the most annoying issue.

The other issue was the typical zzzzzzzzz noise that followed the engine speed. This wasn't very bad at all. You could only hear it with the boat idling at the dock, radio volume all the way down and you ear within a foot of one of the speakers. This noise I could live with.

So the first thing I did was connect the amp + power lead to the common of one of the battery switches. BAM! the whistle noise was gone! Now I only had the faint zzzzzzzz noise.

So next I ran the head unit power right to the amp where the power comes in. (the radio power line has it's own fuse) Once I did this the zzzzzzzz noise went away. I mean it went all the way away. I put my ear right to the speaker and couldn't hear anything.

I have installed a lot of big stereo systems over the years, but there is always something new to learn.

I'm happy! Thanks again!!

Also....I did put those extra speakers in the back of the boat and simply wired them to the mid ship speakers which is the "rear" on the amp. It sounds fantastic!!
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Old 08-31-2012, 05:21 PM
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Ur welcome
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Old 09-06-2012, 08:27 AM
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I had a similar issue with the older JL m6600 amp and mono block. I ended up lowering the gain and installing ground loop isolators. It helped somewhat, but I was not about to rewire the amps on that Coastal, getting wires from the cabin to helm and the batteries in the transom was a total nightmare. On my Hydra, I have the batteries in the center and I hope I wont get the noise once I install. I still need to buy a head unit and amp, planning to stick with Fusion and JL.

This post was a wealth of knowlege.
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Old 06-16-2016, 07:02 PM
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Originally Posted by ScarabChris View Post
Dude you're my f-ing hero!

OK so here is was I was dealing with. The system had two separate noises. One was the high pitch whistle once the engine RPM's went past 1200-1500. This was the most annoying issue.

The other issue was the typical zzzzzzzzz noise that followed the engine speed. This wasn't very bad at all. You could only hear it with the boat idling at the dock, radio volume all the way down and you ear within a foot of one of the speakers. This noise I could live with.

So the first thing I did was connect the amp + power lead to the common of one of the battery switches. BAM! the whistle noise was gone! Now I only had the faint zzzzzzzz noise.

So next I ran the head unit power right to the amp where the power comes in. (the radio power line has it's own fuse) Once I did this the zzzzzzzz noise went away. I mean it went all the way away. I put my ear right to the speaker and couldn't hear anything.

I have installed a lot of big stereo systems over the years, but there is always something new to learn.

I'm happy! Thanks again!!

Also....I did put those extra speakers in the back of the boat and simply wired them to the mid ship speakers which is the "rear" on the amp. It sounds fantastic!!
Hello,

I found this post via search and need to bring it back to life. I am having this same exact problem you are describing. Same setup as you ScarabChris. I've got a total of 4 batteries wired exactly as you described. Before following the steps provided by BradV, i wanted to know how to apply this on 3 amps? I have 3 JL M6600's that are each wired directly to battery.

Thanks!
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Old 06-17-2016, 05:21 AM
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