Engine noise in my tower speakers

[ATK 0]

I kind of got a similar problem. My tower speakers work well for about 3 hours. After that, I get a buzzing noise coming out of them. The volume of the buzzing does not change whether the boat is running or off. If I turn the stereo off for a couple of hours and start it up again, the buzzing noise is gone. My tower speakers are Exile sxt65Q and the amp is an Exile sm400. I did notice that the amp is quite warm compared to my other amp which is an Eclipse xi1200 that runs a sub and 4 in boat speakers. Any help would be great. I was thinking the amp was starting to overheat and cause the buzzing noise? Any help would be great. Thanks

[Wylie_Tunes 146]

When the buzzing starts, power down, pull the RCA cable from the amp and plug up a 3.5mm head-phone jack x RCA cable in thier place. Turn the system back. Turn the heard-unit volume down and use the MP3 players as your music source. Id the noise is still there, then its generated by the amp. If the noise is gone, then is coming upstream from the head-unit. Next step would be to swap the RCAs at the head-unit to see if the noise now transfers to the in-boat amp/speakers.

[DavidEM 1]

If the problem is speaker related due to the speaker heating up then the buzz would be tied to variances in the program material or amplitude. If the noise is constant, independent of the boat, and is present with another source then that would indicate a problematic amplifier.

Normally you would not need a substitute source in order to isolate the noise as an internal amplifier issue. An open input would be sufficient. But in this case, as Wylie indicated, you probably need to keep the amplifier more than just powered up and keep it stressed to get a good diagnosis.

 

David

[ATK 0]

Thanks Wylie and David. I will see if I can get out on the water today for more than a few hours to hear the noise. I do know that the noise is constant after it starts even when I'm not playing music but have the stereo button in the on position. The static noise level does not change even when I turn the music up or really low.

[truekaotik 458]

You may just be getting interference from another electronical device if it's constant and doesnt change with RPMs as well.. Keep that In mind...

[ATK 0]

I did some more investigating and it turns out my problem is the same as the earlier posted problems. I thought it only got a buzzing noise after a few hours thinking that the amp was heating up or something. Turns out the buzzing noise is only in the tower speakers when the engine is running. When the engine is off it is perfect. I made sure the amps are all powered and grounded to the same battery. I switched the RCA cables and its still just in the tower speakers. I made sure that the power wires are not crossing any of the tower speaker wires. When I removed the RCA cables from the in boat speaker amp and just ran the tower speaker amp and tower speakers, the noise in the speakers were gone. I am At a loss of what to do next.

[truekaotik 458]

Are you running a zld, 420 or equivalent? Or is it a straight run from head unit to amp?

[ATK 0]

I'm running the head unit straight to the amp with RCA cables. Sorry but I do not even know what a 420 or zld is.

[Wylie_Tunes 146]

I did some more investigating and it turns out my problem is the same as the earlier posted problems. I thought it only got a buzzing noise after a few hours thinking that the amp was heating up or something. Turns out the buzzing noise is only in the tower speakers when the engine is running. When the engine is off it is perfect. I made sure the amps are all powered and grounded to the same battery. I switched the RCA cables and its still just in the tower speakers. I made sure that the power wires are not crossing any of the tower speaker wires. When I removed the RCA cables from the in boat speaker amp and just ran the tower speaker amp and tower speakers, the noise in the speakers were gone. I am At a loss of what to do next.

 

Dual or single battery setup with multi-battery switch?

 

If you have a dual-battery setup, was if factory or installed afterwords?

 

If dual battery, exactly where are the amps' B+ cables connecting to, directly to a battery or the "C" post of the switch?

 

Next is to determine exactly where the head-unit's BLK ground and YELLOW B+/MEM are termination at. With an OEM wiring harness, its probably easier said then done. At the end of the day, we know that the head-unit is grounded to the battery(s), but probably at a common BUSS bar somewhere. Depending on some different factors, the B+ could be connected directly to a battery, or a common helm BUSS fed through the switch. I would consider running a new wire for each on take them directly to your largest amp's B+ and GND terminal. This insures the entire audio system is sharing the same voltage reference, but it also lets the head-unit take advantage of the large Capacitors in the amp.

 

The fact that the noise is not present when the in-boat amp RCA's are disconnected, and not present when using the same RCA outputs as the in-boat amp, kinda leads to a suspect amp.

[DavidEM 1]

Do these very simple tests.

Remove the RCA inputs on the amplifier with the noise. You do not need a replacement source. Leave the gain as is. If there is still noise there is an issue with either the amplifier or wiring in the speaker path (doubtful in the speaker path but a shorted + or - strand can induce noise into the entire amplifier circuit). If there is no noise under the above condition then it is probably a relationship issue between audio components in the signal path.

Disable the tower system so you can listen to the in-boat amplifier with isolation. Place your ear right up to one in-boat coaxial. Maybe elevate the gain some but don't peg it. You may have noise here that is otherwise less obvious.

If you confirm that the noise is a component to component ground or supply relationship issue then follow Wylie'snstructions. However, the most important point of reference in eliminating any difference in voltage potential is between the audio components in the signal path making the battery supply and ground a secondary concern. If the source unit and amplification are in close proximity then common supply points at a single battery (whether by a direct connection or via a dual battery switch) are acceptable. If there is an appreciable distance between the source electronics and the amplification then I would prefer the reference point as close to the amplifier(s) primary terminals as possible.

 

David

[truekaotik 458]

I'm running the head unit straight to the amp with RCA cables. Sorry but I do not even know what a 420 or zld is.

They are EQs basically... So that's out...

Did you have them hooked up working fine for days, months, years? Or was this a fresh install of tower speakers and you notice the noise right away? You MAY not have to do all they suggested if we can narrow down when they started to make noise...

 

Take your ground from the back of the head unit, cut it and run a fresh wire from it directly to the amp battery or ground block.. That will prolly fix your problem

Edited July 22, 2012 by truekaotik

[ATK 0]

Thanks Wylie, David and True for responding. I did not make it out on the water today because it rained all day. Hope the weather is better tomorrow to try all the things that you guys suggested. Here are some answers to the questions asked. I have a dual battery system with a multi selector switch. I bought the boat used so I'm not sure if it was factory installed. There is a power wire that comes out of the selector switch that goes to a fuse block. On the other end of the fuse block, there are two 4 gauge wires that go to each amp. Each amp is grounded directly to a battery. The tower speakers were installed a few weeks ago and I noticed the annoying noise in the speakers the first time out on the water. Urrgghhhh !

[DavidEM 1]

Follow this very simple rule whenever you have a dual battery switch without an ACR/VSR:

All grounds are common.

Only the dual battery switch should be wired battery-direct (except for a bilge pump/float switch when applicable). The alternator/starter feed, helm buss and ALL audio equipment should be connected to the output/common post of the dual battery switch.

If any electrical component circumvents the switch you are inviting noise. The above scheme absolutely eliminates the potential for conflict under all circumstances.

In the end, you still may have to lift the source unit +/- from the factory harness and reference these connections with the amplifier(s) primary terminals.

 

David

[harlobra 24]

Re-wire the head unit's power wire to the same source as the amps and the ground to the same ground post. It's not dificult to do and fixed mine which sounds like the same problem.

 

(null)

[ATK 0]

Thanks Halobra, I was not able to pull up the picture that you sent. I will try to give that a shot as well. David, I think what you are saying is that I should ground the amps to the BUSS bar? Sorry, I have been googling things like B+, BUSS bar etc because I had no idea what they meant. I am a dolt with electronics. Hope to get out on the water tomorrow. Raining hard again today.

[truekaotik 458]

ATK,

They are suggesting doing what I suggested as well...

Take your black wire from the back of head unit, cut it, run a new wire over to the battery that has both amp grounds on it and connect it there.... Also do the same thing with the yellow wire on the back of the head unit BUT connect it to the positive terminal of the battery that should fix the issue...

[Wylie_Tunes 146]

Thanks Halobra, I was not able to pull up the picture that you sent. I will try to give that a shot as well. David, I think what you are saying is that I should ground the amps to the BUSS bar? Sorry, I have been googling things like B+, BUSS bar etc because I had no idea what they meant. I am a dolt with electronics. Hope to get out on the water tomorrow. Raining hard again today.

 

I would recommend connecting the amps' ground cable directly to the battery. If you have multiple amps that are fed through distribution blocks, then the main trunk line needs to go to the battery ground.

 

B+ = battery positive terminal

BUSS = is a terminal strip or block that allows for a single battery cable to connect to for the purpose of distributing to multiple devises.

[harlobra 24]

Re-wire the head unit's power wire to the same source as the amps and the ground to the same ground post. It's not dificult to do and fixed mine which sounds like the same problem.

 

(null)

I posted from my phone I don't know why it tried to upload a picture...

[Wylie_Tunes 146]

Fallow Davids advice in regards to the head-unit wiring, he has it correct.

 

Do not connect the head-unit's yellow B+/MEM wire directly to a battery in a dual battery w/switch setup. It needs to go to the "C" (common) post of the switch. This insures that the entire audio system shares the same battery source, other wise, you are inviting noise, which is what you are fighting now.

[DavidEM 1]

ATK,

Generally a 'buss' refers to the heavy barrier strip under the dash. Don't use that even though it may be an improvement over the factory harness because you don't know the total length of cable, the number of splices or the gauge of wire throughout the entire factory harness path.

And don't go battery-direct on the positive lead IF you have a dual battery switch.

The ideal location to secure the source unit supply and ground would be the distribution blocks closest to the amplifiers.

Go with a 14-gauge +/-. 12-gauge over a 15 to 20 foot run isn't too much if you will be adding a processor (EQ or line driver) and/or an ipod supply shared on the line. Anything larger is a waste with the limited current draw.

Here is the bottom line: You want the absolute lowest resistance between the supply + and - of all the components in the signal path. Focus on this singular objective.

 

David