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JoeMama

Relocate Amps?

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JoeMama

Hi,

I have a low volume hiss noise which is so aggravating. After quite a bit of research and studying it seems the system should have been installed much better.

Malibu installed my 2007 23ft LSV as follows. I am sure most of them are this way.

1) Putting the stereo amplifier away from the head unit. This can cause noise as preamp wires are probably > 12ft.

2) Putting the amps right next to the batteries. This can cause noise.

3) Using RCA coax to connect from amp to stereo. This can cause noise. Should have been shielded twisted pair

4) non twisted for speaker wires. Should be 12G twisted. Has anyone actually looked at how the speaker wires are routed from amp to speaker. It seems they re-used the regular path of the speaker wires coming from head unit. As such some get -rerouted all over the place. Some seem to run 3/4 the distance around the perimeter of boat.

5) Seems that stereo head unit power/ground is not separate and not connected directly from amp supply.

So my questions are:

1) Anyone move their amps to the starboard side of boat closer to stereo?

2) Is it easy to run wires across the boat underneath the floor as opposed to around the perimeter?

3) I have test drove a few Malibus and noticed the same humm at low volume. Did most of the fixes just come from going to twisted pair pre-amp and also using an amp with a differential balanced input. I just realized that some amps have differential balanced RCA inputs (like the JL amps)

4) Or did the fix also involve running tick ground/power from amp to stereo head?

Thanks

.

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MLA

Before gutting the entire system, it would be worth checking a few things. Is the noise present all the time, or just with the engine running? Noise is usually a result of the source - head-unit or MP3, pre-amp signal path - poor cables, poor or corroded connections, improper routing, or the amp itself. it very very rare that white noise, static or hiss is introduced on the speaker side of the amp. Noise can also be introduced into the source when the head-unit and amp does not share the same B+ and GND source

1) Gain settings: what you describe, sounds like gain hiss. Having the gains set too high will induce some hiss thats noticeable when the volume is real low of there is no music playing. Turn them down a couple ticks and see what happens

2) Source: Power the system up with the RCA cables disconnected from the amps. If gone, you know its upstream, if still there, its in the amp and revert to #1. If gone, then plug the RCA cables back up, then unplug them from the head-unit and retest. If it goes away with the RCA's disonnected from the head-unit, you now know its the source.

3) try a CD, FM radio and AUX. It the noise/hiss same or different with the different sources? You can also plug an MP3 right into the amp.

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Earmark Marine

Joe,

I couldn't agree more with MLA. Don't go making wholesale changes in your system. Find the true causes of noise via a logical process of elimination.

It appears that you may have done a little reading on the internet where anyone can be a keyboard expert. In reality most of the items on your list are unlikely to be the true cause of the noise. Making some of the changes could even induce more noise.

David

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sp0tts

3) I have test drove a few Malibus and noticed the same humm at low volume. Did most of the fixes just come from going to twisted pair pre-amp and also using an amp with a differential balanced input. I just realized that some amps have differential balanced RCA inputs (like the JL amps)

David and MLA have you on the right track here. Most of us put our amps in the passenger side compartment b/c it is ideal for them to be close to the batteries (shorter DC runs = less voltage drop = most ideal); and there's more space in that compartment than pretty much anywhere else we could safely put amps.

Edited by sp0tts

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Deephaven

Malibu installed my 2007 23ft LSV as follows. I am sure most of them are this way.

1) Putting the stereo amplifier away from the head unit. This can cause noise as preamp wires are probably > 12ft.

2) Putting the amps right next to the batteries. This can cause noise.

3) Using RCA coax to connect from amp to stereo. This can cause noise. Should have been shielded twisted pair

4) non twisted for speaker wires. Should be 12G twisted. Has anyone actually looked at how the speaker wires are routed from amp to speaker. It seems they re-used the regular path of the speaker wires coming from head unit. As such some get -rerouted all over the place. Some seem to run 3/4 the distance around the perimeter of boat.

5) Seems that stereo head unit power/ground is not separate and not connected directly from amp supply.

1) Not really. Noise would be caused not by the length which only in turn has a small voltage drop, but instead by cheap wiring or poor termination. Length of 12' is not a long run.

2) Again, not really. Unless DC noise is a concern to you. IMO, it is a huge advantage as you can shorten the voltage and ground leads which are more expensive than the RCA's.

3) Shielded wire is cheap insurance and should always be used even though regularly it is not necessary. In the case of Malibu, I'd bet they've tested it and for a properly setup system is fine.

4) 12g is WAY bigger than necessary for speakers unless you have RIDICULOUSLY long runs. Even then the power drop is minimal and size has nothing to do with noise. Considering that the Malibu is primarily a DC vehicle running twisted lines for the higher voltage stuff (read speaker wires) is completely unnecessary.

5) If by amp supply you mean battery termination then ok...sort of. Realistically a good connection is all that is required. Nothing loose and the more direct the better.

So my questions are:

1) Anyone move their amps to the starboard side of boat closer to stereo?

2) Is it easy to run wires across the boat underneath the floor as opposed to around the perimeter?

3) I have test drove a few Malibus and noticed the same humm at low volume. Did most of the fixes just come from going to twisted pair pre-amp and also using an amp with a differential balanced input. I just realized that some amps have differential balanced RCA inputs (like the JL amps)

4) Or did the fix also involve running tick ground/power from amp to stereo head?

1) Won't help at all.

2) Perimeter length doesn't effect the noise at all so don't worry about it

3) 90% of the time hum is caused by overzealous gain setting. The other times are by faulty wires or connections *caveat assumes at least some capability in the install process by the installer

4) This is rarely a bad idea. In car audio, a bad headunit ground is almost always the source of untraced noise *with the same caveat as above

Definitely follow MLA's advice. Finding the source is always the first step in fixing it. Currently you are chasing all sorts of things that probably aren't the cause.

One further question, is this the stock unit or an aftermarket? If its an aftermarket is it a Pioneer?

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JoeMama

1) Not really. Noise would be caused not by the length which only in turn has a small voltage drop, but instead by cheap wiring or poor termination. Length of 12' is not a long run.

2) Again, not really. Unless DC noise is a concern to you. IMO, it is a huge advantage as you can shorten the voltage and ground leads which are more expensive than the RCA's.

3) Shielded wire is cheap insurance and should always be used even though regularly it is not necessary. In the case of Malibu, I'd bet they've tested it and for a properly setup system is fine.

4) 12g is WAY bigger than necessary for speakers unless you have RIDICULOUSLY long runs. Even then the power drop is minimal and size has nothing to do with noise. Considering that the Malibu is primarily a DC vehicle running twisted lines for the higher voltage stuff (read speaker wires) is completely unnecessary.

5) If by amp supply you mean battery termination then ok...sort of. Realistically a good connection is all that is required. Nothing loose and the more direct the better.

1) Won't help at all.

2) Perimeter length doesn't effect the noise at all so don't worry about it

3) 90% of the time hum is caused by overzealous gain setting. The other times are by faulty wires or connections *caveat assumes at least some capability in the install process by the installer

4) This is rarely a bad idea. In car audio, a bad headunit ground is almost always the source of untraced noise *with the same caveat as above

Definitely follow MLA's advice. Finding the source is always the first step in fixing it. Currently you are chasing all sorts of things that probably aren't the cause.

One further question, is this the stock unit or an aftermarket? If its an aftermarket is it a Pioneer?

The Head unit is a Sony.

Here's my test results. Again only noise when engine is running.

o Tried Stinger twisted pair 8000 series and has more noise than standard cheap RCA!!! Then measured Stinger twisted pair GND resistance and its 1.6 Ohms which was a surprise. They obviously use small gauge twisted pair. This implies that noise is coming from head unit and resistance thru cable GND causing noise.

o No noise when connect Iphone directly to amp thru the same long length RCA cables. Implies that all noise coming from head unit

o No noise when unplug RCAs from stereo. Implies that all noise coming from head unit

o Noise when just connect RCA ground to stereo chassis. Implies ground noise over RCA is culprit.

o Unplugged stereo antenna, bus aux in, bus control, .And connected GND from battery to stereo with fat wire (jumper cable) and still noise. This was unexpected as it should have removed the ground current on RCA. This must mean the noise is being injected onto the RCA inner conductor as well.

o ALT on bat 1 and boat power on bat 2. Same noise. ALT on bat 2 and boat power on Bat 1 same noise.

o Connected (literally) jumper cable from bat pwr/gnd to stereo pwr/gnd and still noise.

BUT the strangest thing is changing the Throttle a little bit removes the noise. so if I move the throttle forward such that the boat is not really moving and then barely move the throttle I can get the noise to go away and come back. So this implies that the noise is coming from the throttle and then thru the stereo or that the throttle is just affecting the noise somehow.

Seems to point to the electronic throttle. Hence my other post on how to dis-assemble the throttle.

Also, just bought a Jensen XFMR CI-2RR ($188) to put right before the amp just to prove I can get the noise to go away. As that's supposed to get rid of any issue.

Got about 15 hours into this....

my other two tests are to move stereo right near amp and see what happens. And also try new stereo head unit.

Edited by JoeMama

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Earmark Marine

Sounds like you just about have it isolated. You are close to having a black and white cause.

The most important relationship to have low resistance and therefore no potential difference is between those items 'in' the signal path. So get your head unit ground and supply directly from the primary terminals of your highpass amplifier. Use just one amplifier to begin with and disconnect all others. A 14-gauge power and ground for your HU should be more than sufficient but you can go to 12-gauge if you want. Anything over that couldn't possibly make a difference.

Set it up so you can temporarly move the HU around moving the HU away from the dash, high current cables, modules, batteries and amplifier switching power supplies.

Look inside the HU chassis for any evidence of water damage, corrosion, a white residue or minerals spots or any other foriegn build up.

Try a substitute HU. If an ipod is battery operated it can't really cause a ground or supply loop so this may not be a conclusive test. But it probably does elininate the amplifier as the culprit.

You must first confirm that you have good voltage before you can do any meaningful diagnosis. Hopefully you did this out of the gate. And measure it at the amplifier primary terminals while its under load rather than at the battery.

David

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