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  #41  
Old 07-12-2013, 10:14 PM
chevyluv chevyluv is offline
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so i took a look today at how mine is wired up both amps are grounded to the negative pole of the battery stereo is grounded somewhere else. positive leads all go to the same spot on the dual battery switch.

how do i set the gains and should i find the stereo ground and switch it. ?
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  #42  
Old 07-13-2013, 12:31 AM
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Originally Posted by chevyluv View Post
so i took a look today at how mine is wired up both amps are grounded to the negative pole of the battery stereo is grounded somewhere else. positive leads all go to the same spot on the dual battery switch.

how do i set the gains and should i find the stereo ground and switch it. ?
The head unit's ground should be the same point as the amps.
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  #43  
Old 07-13-2013, 01:46 AM
chevyluv chevyluv is offline
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so i should run a new ground from the head unit to the negative point of the battery aswell?
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  #44  
Old 07-13-2013, 05:04 AM
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Originally Posted by chevyluv View Post
so i should run a new ground from the head unit to the negative point of the battery aswell?
If you're using the stereo wiring in the dash, disconnect that and run a new one to the amplifier(s) and connect it to the amp's ground terminal or if you have a distribution block, connect it to that. If you were to measure teh resistance from the ground wire that's being used for the head unit and and amp, you would probably see a few Ohms and that's more than enough to cause a ground loop and this noise.
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  #45  
Old 07-14-2013, 08:43 PM
chevyluv chevyluv is offline
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Well after much digging I think I have found the problem the ground from the stereo does not go to the anp ground or the battery it apears to go around the bow and to the grounding bar. If I cut this wire and run it to the amp or negative terminal of the battery should this solve my problem?
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  #46  
Old 07-14-2013, 10:38 PM
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Originally Posted by chevyluv View Post
Well after much digging I think I have found the problem the ground from the stereo does not go to the amp ground or the battery it appears to go around the bow and to the grounding bar. If I cut this wire and run it to the amp or negative terminal of the battery should this solve my problem?
Run it to the amp.

Here's the theory behind this- the power and ground cables for the head unit and anything that would go between the head unit and amp(s) should be as short as possible and should go to the same point where the amp(s) get their power and ground. The easiest way to do this is by using a distribution block for each. One of the head unit's power wires is constantly hot and the other is switched (ignition switch or accessory switch), usually connected to a specific set of wires in the dash. This uses a ground wire that connects to a common point, often a buss strip or one point before heading back to the battery. All of these work well enough as long as there's nothing else in the audio system but if there is more, it brings trouble. An easy way to avoid using a power wire that takes a different path is to use a Bosch-style relay to interrupt the switched wire and use that as the relay's trigger, instead. The relay's input tab (30) connects to the wire that's constantly hot and the output (87a) goes to the head unit's switched wire. Tabs 85 and 86 connect to the red switched wire in the dash and a ground wire, respectively. You can use the old radio ground wire for this.

Electrically, no resistance between the head unit and other electronics is allowable because this causes the power voltage to drop. The voltage will find a path and it doesn't care where it has to go to achieve this. The most common route is through the audio cable shield. The reason this is a problem is because the audio circuit is isolated from the chassis of the equipment and is used for signal that's AC (Alternating Current", not DC. AC and DC on the same circuit is a bad thing and affects the AC circuit's operation, either by introducing noise, affecting gain or by damaging the circuit(s), depending on how much resistance is on a power cable. If the power amp ground cable is lifted, the amp(s)' power supply current will have to pass entirely through the audio circuit and with a high powered amp, or several, it means 50A or more will try to pass on wires that can't support that much. This will let the magic smoke out of the wires.
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  #47  
Old 07-15-2013, 08:15 PM
chevyluv chevyluv is offline
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well im pretty happy im pretty sure i have it fixed now i found the b+ and the negative were headed around the boat and grounded and powered from where the instruments and such were. i took the b+ and the ground from the stereo and ran them to the amp. and it seams to have eliminating the feedback from when i would switch lights and the tower lights on hopefully this has eliminated it while the boat is running.

thanks for all of your help it is really appreciated
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  #48  
Old 09-10-2014, 02:12 AM
chevyluv chevyluv is offline
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Well I thought I had eliminated this problem but it's still causing issues. The head unit b+ and ground go to the amps. then the amps neutrals go to one of the batteries. The power comes from the dual battery switch
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  #49  
Old 09-10-2014, 09:29 AM
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Originally Posted by chevyluv View Post
Well I thought I had eliminated this problem but it's still causing issues. The head unit b+ and ground go to the amps. then the amps neutrals go to one of the batteries. The power comes from the dual battery switch
FYI- DC power doesn't use a neutral, it's just B+ and -.

Moderator-Please Sticky this, David from Earmark- if you have comments, feel free-

- Power cables of adequate gauge from battery to amp location, with distribution block on each.
- Amplifier power- Connect amplifier +/- cables to the appropriate distribution block, using the shortest possible path, avoiding any of the boat's power and control wiring.
- Yellow wire for head unit- Disconnect head unit Battery lead (Yellow) from dash wiring and run new ones, directly to the distribution blocks, using the shortest path that avoids paths that are near the boat's power/control wiring. Also, make sure that if the path must coincide with these, they only cross at a right angle, never parallel.
-Head unit's red wire- from the dash wiring and use a Bosch-style relay, fed by the yellow wire.
- Head unit's ground lead (Black) Disconnect from dash wiring, install a ring terminal and, along with the new ground wire coming from the distribution block that has its own ring terminal, attach to the stud on the back of the head unit.

DO NOT attach any other wires to the head unit wiring or case.
DO NOT bundle the audio cables with any power wiring or the boat's power or control wiring. Parallel cable runs almost guarantee noise problems because of induction.

DO use the metal strap that comes with the head unit to support the back of the head unit, so it can't wobble and damage the head unit, mount or fiberglass around the head unit.
DO install a fuse holder to the new yellow wire

Relay wiring-
Tab 85- connect to the previously abandoned ground wire in the stereo dash harness, using a short section of the head unit's ground wire.
Tab 86- to the previously abandoned switched red wire under the dash, using a short section of the red wire on the head unit, with a properly crimped terminal.
Tab 30- Connect to the new yellow wire from the distribution amp, using a properly crimped terminal.
Tab 87- Connect the head unit's red wire, using a properly crimped terminal.

I have used relatively expensive audio cables and really cheap ones- routed properly, neither picked up noise. Also, any supposed "audiophile" sound quality benefits will be lost as soon as you're outside and especially with the engine running.


If you use two batteries, place them near each other, connect all of the cables to ONE of the batteries and use a pre-made 2ga battery cable between the appropriate posts. If you make your own, crimp AND solder the ring terminals on, using a soldering gun, not a soldering iron- an iron will never get the wire & terminal hot enough for the solder to flow properly.

Note- if you have a tinning iron for sheet metal, that will work.

If you use a 1/2/Both battery switch, put it as close to the batteries as possible and use the shortest cables possible.

The reason for wiring the head unit through a relay is for isolation- the red wire in the dash harness is only used to latch the relay, so it can't cause noise. You don't want to use any of the dash harness wires to power or ground the head unit- the resistance on the power wires to the power amps and to the Stereo harness in the dash won't be the same and the difference will be made up using the easiest path, which happens to be on the shield of the audio cables. That's called a 'ground loop' and a noise filter on the power wires won't help. A ground loop isolator can, but the cheap ones usually degrade the sound quality.

Audio cables near control cables or wiring that has noise from an alternator being stressed (because it wasn't upgraded to handle the extra load from added amplifiers and other accessories) can pick up that noise. If you move the cables farther from other wiring and the noise decreases, find a path that doesn't pick up any noise. It's more difficult and expensive to attempt to shield the cables than it's worth.
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  #50  
Old 09-11-2014, 06:26 PM
chevyluv chevyluv is offline
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http://www.princessauto.com/mobile/p...uctID=8573834o

for a relay is this what I'm looking for ? Also I don't think there are any distribution blocks. If check but the boat os an hour away right now.
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