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Fab
11-27-2011, 11:49 AM
Hi,

I need some advice on a little thing i noticed in my 2008 X2 i recently purchased :

I noticed that there is a crackling noise coming from the speakers(all the sepakers, no matter the source input i choose), but only when the engine is running ?!! if i turn the volume higher i don't hear this noise but at low volume it's clearly disturbing.

When the engine is off, with the key turned on left position to have audio, the sound is clear...

I thought it may be something about the batteries, some electrical interferences ??

what do you guys think ?

willyt
11-28-2011, 10:06 AM
Definitely an alternator whine... Search that and you should find a solution here.

JimN
11-28-2011, 10:10 AM
Hi,

I need some advice on a little thing i noticed in my 2008 X2 i recently purchased :

I noticed that there is a crackling noise coming from the speakers(all the sepakers, no matter the source input i choose), but only when the engine is running ?!! if i turn the volume higher i don't hear this noise but at low volume it's clearly disturbing.

When the engine is off, with the key turned on left position to have audio, the sound is clear...

I thought it may be something about the batteries, some electrical interferences ??

what do you guys think ?

List all of the components in the audio system. Did you install the system, or was it in the boat when you bought it?

Clean and tighten the battery terminals, then try it. That can make a difference. Look at the input level settings- are they all turned up, fully? That's not the way they're supposed to be set. The JL Audio website has a procedure for setting the input levels and it's the best way I have seen without needing an oscilloscope.

EarmarkMarine
11-28-2011, 11:01 AM
Fab,
It would be helpful if you could describe the crackling noise as something that has a tempo that increases or decreases with engine RPM. Or, is it steady? Is it more of a high pitched whine like a siren or more of a ticking?
Is the noise the same on all audio sources such as ipod, CD and tuner?
Excluding the subwoofer because the lowpass crossover often filters the noise, is the noise in all or just a portion of the speakers?
Then certainly look into the points that Jim mentioned, especially if the amplifier gains are wide open.
There can be a substantial amount of resistance in the HU grounding given the small gauge, long run and multiple connections before it references the battery. If there is a difference between the potential of the HU and the amplifiers' ground or supply then this can introduce a noise loop. Or if the HU is getting its supply off of one battery while the amplifiers are getting their supply off of an alternate battery then this is sure to induce noise. You may have to verify that all audio equipment supplies are to a common point and all audio grounds are to a common point. And you may have to remove the HU from the factory harness and connect it to the battery direct as the amplifiers are or very close to the primary terminals of the amplifiers. Use no less than 14-gauge for this.
Make sure that all RCA cable ends are completely and tightly seated.
Thats a start.

David
Earmark Marine

agarabaghi
11-28-2011, 11:14 AM
Check your ground, more often than not engine noise (if that is what it is) comes from a bad of poorly secured ground.

Also check that your rca cables are not running near main power cables or batteries.

davidstan
11-28-2011, 01:23 PM
Took me 3 months to figure out this noise problem. I tried everything within reason and w/ help from Jim and Earmark and some dumb luck i got it. I started with the batteries then the rca cable segregation from power lines and then switching cables around to narrow down the problem as well as checking grounds thoughrally. I installed a ground loop isolator on the inside speaker amp and that semi solved or quite'ed down the noise. But what knocked out the noise completly was simply re-bundleing the cables in a neat package. Prolly combination of a lot of things did it but wow what a relief to have a clear system.

Deltaxstar
11-28-2011, 02:47 PM
Make sure all your grounds go to the same battery that powers the amps if you landed grounds on a different battery then the 12v is pulled off of it could create noise.

Thrall
11-28-2011, 03:18 PM
Same issue with Davidstan on my 06 with the OE setup.
I did a serious upgrade to my system after the 1st season anyway and the noise was gone.
Firends X15, same thing. IMO MC builds a top quality boat and then installs expensive components like cr@p.
CLean up the wiring, make sure power/gnd wires are not running parallel bundled with RCA cables. Make sure all gorunds are of the same guage as the power wire. Dedicated ground for each battery if you have 2 and all components running from each battery are grounded the same (ie dont have the + wire for a component from battery 1 and the - wire from the same component off of battery 2).

Fab
11-28-2011, 03:37 PM
Thx for the tips !

I have the OE setup with two batteries, two amps, one for cockpit speakers and one for two tower speakers...it's a high pitched noise, but it doesn"t increase with engine RPM, if i turn the volume louder this sound doesn't increase, you can only hear it at low volume...

Whatever source input i choose it goes the same, on all speakers...

Gonna try what you told me, the strange thing is that it seems that this noise is recent, i purchased the boat recently and i didn't notice this noise at the begininng ?!!

swatguy
11-28-2011, 05:11 PM
while by no means an expert like Earmarark or Jim, I am betting maybe someone bumped a gain/crossover or something from the way you describe, or there is a bad ground that got loose. Make sure your head unit is grounded to the same place your amps are. This liitle thing eliminates a lot of issues.

With that said wakeboat dealers and factories are far from stereo gurus, They tend to wire things the easiest way in most cases, which isn't always the "best" way.

EarmarkMarine
11-28-2011, 06:42 PM
Good point in that its a towboat so things can easily change. Corrosion happens in marine. Terminations get loose from the shock and vibration. Things do get bumped in storage lockers.

David
Earmark Marine

mikeg205
11-29-2011, 12:28 AM
Great advice... RCA cables are the worst.... go digital anytime you can... they are like antennas...If there's a college near by post a flyer for an electronics geek to check the wiring...one wrong connection can cause feedback to travel against the logical flow of current...I even had old spark plug cables cause audio problems in cars I have had.... Good Luck

JimN
11-29-2011, 08:23 AM
Great advice... RCA cables are the worst.... go digital anytime you can... they are like antennas...If there's a college near by post a flyer for an electronics geek to check the wiring...one wrong connection can cause feedback to travel against the logical flow of current...I even had old spark plug cables cause audio problems in cars I have had.... Good Luck

RCA cables work fine- the problem comes when grounding integrity decreases or fails, due to corrosion, strain or someone adding things to an electrical system that's already at it's limit for noise rejection. Bundling cables from a head unit to an amp seems logical- they're all "part of the audio system, so what can it hurt?", right? That causes issues because the person bundling the cables may not know/understand that when current flows, a magnetic field is created and proximity to the field can induce current flow in audio cables. If the power cables are carrying noise, that noise can be transferred to the audio cables and, while it may seem that a ground loop is present (the noise goes away when the audio cables are unplugged), it's still there when a ground loop isolator is used. The whole signal path and power/ground circuit needs to be considered when searching for the cause of noise issues and the recommendations have been listed in many threads before this one. Anyone who connects the + for an amp to one battery and the ground to another proves that they don't know what they're doing, either because they don't understand the circuit or because their wiring practices are sloppy.

BTW- not that many college students will know how to fix this kind of problem- in a lot of cases, even if the "If this happens, do this to fix it" list is followed to the letter, it's not guaranteed that the problem will be cured. Sometimes, after the list of "Always do this/never do this" and "you might try this" is used, it can be time for "That will never work", as long as it's not going to cause a safety issue.

Re: "go digital anytime you can"- how would someone "go digital" between a head unit and an amplifier"? If you use a digital coax cable, you can still have a ground loop. That's the one benefit of using optical connections in current applications- it's not an electrical connection. The reason I say it's 'the one benefit' is that optical isn't used enough. One optical cable could be used instead of HDMI, all audio channels, all video and a lot more, if they wanted to make that happen. It's not cheap to use a media converter, though.

agarabaghi
11-29-2011, 09:18 AM
I'd like to bring up a question about RCAs...

Since they are analog, I'm guessing there is a difference between the quality of RCA cables from one to another. Is it worth the extra penny to spend on them?

I picked up some 25ft RCA cables from MONOPRICE.com and they seem to do the job fine, as long as they are not near the batteries or power wires. Will I notice any differnce with higher end, fancy looking RCA cables?

mikeg205
11-29-2011, 09:20 AM
RCA cables work fine- the problem comes when grounding integrity decreases or fails, due to corrosion, strain or someone adding things to an electrical system that's already at it's limit for noise rejection. Bundling cables from a head unit to an amp seems logical- they're all "part of the audio system, so what can it hurt?", right? That causes issues because the person bundling the cables may not know/understand that when current flows, a magnetic field is created and proximity to the field can induce current flow in audio cables. If the power cables are carrying noise, that noise can be transferred to the audio cables and, while it may seem that a ground loop is present (the noise goes away when the audio cables are unplugged), it's still there when a ground loop isolator is used. The whole signal path and power/ground circuit needs to be considered when searching for the cause of noise issues and the recommendations have been listed in many threads before this one. Anyone who connects the + for an amp to one battery and the ground to another proves that they don't know what they're doing, either because they don't understand the circuit or because their wiring practices are sloppy.

BTW- not that many college students will know how to fix this kind of problem- in a lot of cases, even if the "If this happens, do this to fix it" list is followed to the letter, it's not guaranteed that the problem will be cured. Sometimes, after the list of "Always do this/never do this" and "you might try this" is used, it can be time for "That will never work", as long as it's not going to cause a safety issue.

Re: "go digital anytime you can"- how would someone "go digital" between a head unit and an amplifier"? If you use a digital coax cable, you can still have a ground loop. That's the one benefit of using optical connections in current applications- it's not an electrical connection. The reason I say it's 'the one benefit' is that optical isn't used enough. One optical cable could be used instead of HDMI, all audio channels, all video and a lot more, if they wanted to make that happen. It's not cheap to use a media converter, though.


Going digital... good point... my car has optical into the pre-amp...wire harness to amp...shielded coax to amps and shield cables to speakers. A college kid may have access to meters to isolate where the noise is originating... and where it needs to be isolated.

agarabaghi
11-29-2011, 09:23 AM
I doubt his boat stereo has optical...

mikeg205
11-29-2011, 09:30 AM
I doubt his boat stereo has optical...

Get a new receiver...help the economy....:D

agarabaghi
11-29-2011, 09:35 AM
Ive never even seen a headunit for a car or boat with optical ...

EarmarkMarine
11-29-2011, 11:38 AM
In our experience the proximity of RCAs to power wiring is rarely the noise issue but then we always try to provide a little separation between the two when running long and coincidental paths. Generally crossing paths at a right angle at the amplifier cable layout or a short overlap for example is not a problem. But then there is always the low percentage exception when the boat has a problem with an engine management module or other and we have had to get really intense about how we laid everything out. We wouldn't even allow the RCAs to cross paths with the primary wiring at the amplifiers and that isn't particularly easy to do if all terminals and connections run down a single side of an amplifier. But the RCA proximity cause is really one of the easiest to diagnose by simply running a substitute RCA external to the path. In extreme cases where the boat is the legit cause rather than the installation execution we use the probe side of a tone and probe kit to identify out of the ordinary sources of noise radiation. But again, this is such a very, very small percentage of the time versus the many other culprits.
Btw, I wrote a comprehensive noise diagnosis draft for our customers. It covers everything that we have experienced in over 30 years in the mobile electronics business. You don't want to read it just for fun. But for those customers who hit the wall with a noise problem it provides a step by step method. And we have whipped every noise problem we have encountered. I will tell you that in most cases the remedies are simple and have been covered well by Jim and others in this thread. Most people are looking for the easy answer and are reluctant to really roll up their sleeves and get after it.

David
Earmark Marine

JimN
11-29-2011, 12:32 PM
Going digital... good point... my car has optical into the pre-amp...wire harness to amp...shielded coax to amps and shield cables to speakers. A college kid may have access to meters to isolate where the noise is originating... and where it needs to be isolated.

Shielded wire to the speakers? That's incredibly rare and usually unnecessary. The noise problems come in where the signal level is low and then amplified, not usually after the amplifier. What kind of car is it?

As far as meters, a tape head soldered to a piece of shielded cable, plugged into a separate amplified speaker (available at Radio Shack or Parts Express) is a really good way to sniff out noise. Another is by using a pocket-sized AM radio that has a section of shielded cable connected where the antenna usually is, with the center wire sticking out a little. Tune it to the trouble frequency and move the tip around to find the loudest areas. These only work for radiated noise. though.

A ground loop is a voltage/resistance issue between two pieces of equipment and for this, a multi-meter or test light can be used. If you measure voltage from one piece to another, you'll have a ground loop and as I posted before, the cause and solution have been posted in other threads.

Earmark mentioned a potential difference- potential means voltage because voltage is potential energy and 'potential difference' means that the resistance on the ground connections, wires, etc causes a measurable voltage if you measure between the two pieces of equipment. That's why I and others have recommended running one heavy power (+) and (-) cable, each to a distribution block, then to the amplifier(s). From the distribution block, a smaller but adequate (+) and (-) should go to the head unit and any other pieces in the audio system, using the OEM switched power (+) to latch a relay that sends (+) to the head unit's switched lead. The head unit's ground wire should be looped back onto the case where a separate (-) wire attaches, coming from the ground distribution block. If the RCA cables were pre-made, they're generally fine but there are no guarantees. If they were made for the project, I would start by inspecting the solder joints. A little resistance there will kill an otherwise great system.

JimN
11-29-2011, 12:40 PM
I'd like to bring up a question about RCAs...

Since they are analog, I'm guessing there is a difference between the quality of RCA cables from one to another. Is it worth the extra penny to spend on them?

I picked up some 25ft RCA cables from MONOPRICE.com and they seem to do the job fine, as long as they are not near the batteries or power wires. Will I notice any differnce with higher end, fancy looking RCA cables?

Many tests have been done with listeners who knew when cables were switched, didn't know and when nobody knew which were being used. The only reliable way to know which is which is to know which is being used because the half-blind and double-blind tests didn't have the same results. The differences are too small to hear in most cases and by most people. Most people hear a major difference when they replace a damaged cable with a new one that's pristine. Audio cables don't carry much current or voltage, so shielding is high on the list of important characteristics. As long as the cables don't have high capacitance, inductance (either series or parallel in both cases) or resistance, the signal will pass with minimal change. The high priced cables are great for making the cable manufacturer wealthy, but little else.

JimN
11-29-2011, 12:42 PM
It covers everything that we have experienced in over 30 years in the mobile electronics business.

David
Earmark Marine

Have you ever done a system with an Alpine head unit, Audio Control EQ/crossover and ADS amplifiers? That was almost a guaranteed noisemaker.

EarmarkMarine
11-29-2011, 01:02 PM
Jim,
Early Sony head units and especially early Audio Control EQs in between many HU and amplifier combinations introduced issues with the above-ground RCA relationships and were an absolute nightmare.
Thanks for reminding me.
Early Hondas and early Broncos with the gauge feed running right over the top of a cassette deck with a magnetic pick up sent us all to school.
I certainy don't miss those days. But those experiences make today's problems seem simple.

David
Earmark Marine

JimN
11-29-2011, 01:13 PM
Jim,
Early Sony head units and especially early Audio Control EQs in between many HU and amplifier combinations introduced issues with the above-ground RCA relationships and were an absolute nightmare.
Thanks for reminding me.
Early Hondas and early Broncos with the gauge feed running right over the top of a cassette deck with a magnetic pick up sent us all to school.
I certainy don't miss those days. But those experiences make today's problems seem simple.

David
Earmark Marine

Those made me a lot better when it came to noise problems, I guarantee it. The Chevy Celebrity had a pink heater wire that made it impossible to install Pioneer and many other tape units in-dash without relocating the wire, too. The Cavalier had issues caused by them replacing hood bolts with the black oxide coated ones, which caused the bonding of the hood to fail. In fact, GM had a service bulletin that showed the procedure for repairing these. The Malibu I mentioned in another thread was a piece of cake compared with some of the ones that showed up when I was doing cars, especially when it was new models of cars and head units.

mikeg205
11-29-2011, 03:04 PM
Shielded wire to the speakers? That's incredibly rare and usually unnecessary. The noise problems come in where the signal level is low and then amplified, not usually after the amplifier. What kind of car is it?

As far as meters, a tape head soldered to a piece of shielded cable, plugged into a separate amplified speaker (available at Radio Shack or Parts Express) is a really good way to sniff out noise. Another is by using a pocket-sized AM radio that has a section of shielded cable connected where the antenna usually is, with the center wire sticking out a little. Tune it to the trouble frequency and move the tip around to find the loudest areas. These only work for radiated noise. though.

A ground loop is a voltage/resistance issue between two pieces of equipment and for this, a multi-meter or test light can be used. If you measure voltage from one piece to another, you'll have a ground loop and as I posted before, the cause and solution have been posted in other threads.

Earmark mentioned a potential difference- potential means voltage because voltage is potential energy and 'potential difference' means that the resistance on the ground connections, wires, etc causes a measurable voltage if you measure between the two pieces of equipment. That's why I and others have recommended running one heavy power (+) and (-) cable, each to a distribution block, then to the amplifier(s). From the distribution block, a smaller but adequate (+) and (-) should go to the head unit and any other pieces in the audio system, using the OEM switched power (+) to latch a relay that sends (+) to the head unit's switched lead. The head unit's ground wire should be looped back onto the case where a separate (-) wire attaches, coming from the ground distribution block. If the RCA cables were pre-made, they're generally fine but there are no guarantees. If they were made for the project, I would start by inspecting the solder joints. A little resistance there will kill an otherwise great system.

regarding the shielded cable - mercedes does many unnecessary things... all I know is that I am inviting you over to install my new system one day... the pay is good - good food and free beer....:D