# running rca & power wire together?



## severe (Nov 11, 2003)

will that give me any issues??? 
im installing a sub & amp with an aftermarket HU so i wont even be touching the stock amp and runnning everything from the front. i really have no clue how to take apart the passanger side of the car to run rca's on the opposite side. so will i run into sound quality issues if i run on the same side?


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## kwalton (Sep 3, 2001)

*Re: running rca & power wire together? (severe)*

with just an amp for the sub you should be ok. i have been doing it that way for years with no problems. the only time i would definitely keep them on seperate sides is when i was doing a 4 channel amp for mids.


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## craigsaid (Sep 7, 2005)

*Re: running rca & power wire together? (kwalton)*

Does anyone have any real information on why a power wire would muck with the sound quality? Since the power wire is just carying DC there is no magnetic flux and no AC components. Does anyone know the real electrical reason why interference could be happening?


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## jimix (Jul 21, 2003)

*Re: running rca & power wire together? (craigsaid)*

I'm no audio wiring expert... but any time you have an electrical current there is a magnetic field. I suppose that the field generated by the wire carrying the current could affect the weaker signal currents in the other wires.


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## boogs (Jun 4, 2006)

*Re: running rca & power wire together? (craigsaid)*


_Quote, originally posted by *craigsaid* »_Does anyone have any real information on why a power wire would muck with the sound quality? Since the power wire is just carying DC there is no magnetic flux and no AC components. Does anyone know the real electrical reason why interference could be happening?

why? because you are amplifying the sound. RCA wires are carrying a weak signal from the HU that gets amplified many times over to produce a clear, loud sound through the speakers. Since you are running 12v through a 4 gauge wire, anything that comes in contact with that wire is going to receive some interference. It's not much, but when you amplify it, it's going to sound like a lot. And since the RCAs dont have much insulation to begin with, it just makes it that much worse.
You'll probably be alright with wiring just a sub, because you most likely wont hear the interference at such low frequencies. But if you ever plan on amping your actual speakers, you'll want to relocate the RCAs. And if you dont, you'll know why everyone else does.


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## afinley (Dec 29, 2004)

*Re: running rca & power wire together? (boogs)*

but then again, your entire car has 12v running through it, so i guess run your rcas... under the car?


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## pwnt by pat (Oct 21, 2005)

*Re: running rca & power wire together? (afinley)*

Power wire and rca interferance is just a myth, an urban legend, promoted by too many random variables. Aaron hit the nail on the head.
If you have noise, something else is to blame, not power and ground wires together.


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## jimix (Jul 21, 2003)

*Re: running rca & power wire together? (pwnt by pat)*


_Quote, originally posted by *pwnt by pat* »_Power wire and rca interferance is just a myth, an urban legend, promoted by too many random variables. Aaron hit the nail on the head.
If you have noise, something else is to blame, not power and ground wires together.

No, actually it is supported by the laws of physics. It may take alot of current (like running a sub maybe?) to produce enough interferance to notice, but it will be there. 
Even the small current in telephone wires produces interference. That's why dial-up modems are limited to 56K.


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## afinley (Dec 29, 2004)

*Re: running rca & power wire together? (jimix)*

right, but because its DC, there is just as much current grounding back through your car. so, no matter where you run RCAs, there will be just as much interference.


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## pwnt by pat (Oct 21, 2005)

*Re: running rca & power wire together? (jimix)*

exactly as afinely stated in the post above mine. Every metal piece in your car is directly connected to the negative post of the battery. Therefore, no matter where you have the signal cable, you would still be near a dc source.
The reason you DON'T get noise from putting an RCA near the power cable is because about 99% of the rcas available have adequite shielding to reject noise.
As I said before, if you have noise, it's another problem. Even something as simple as unplugging the rca and replugging it back in (bad connection) could solve your noise problems. If you were to move rca wires from one side of the car to the other, you would change multiple variables, not just one.
A simple test is as follows:
hook your head unit up to a battery (outside of the car). Hook up an amplifier in a similar way with several feet of power and ground wires (6-10ft). Run rcas directly along the power wire. You won't get noise. Why? The RCA's are shielded to reject any possible interference. 
*The ONLY way to keep your rcas away from a DC source in a vehicle is to not put them in the vehicle in the first place.*


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## badb0ybilly (Apr 2, 2007)

*Re: running rca & power wire together? (afinley)*

thats completely different and it all depends on where your amp is grounded to. when you ground your amp to the chassis it dumps all the power there when the amp is done with it... the farther that power gets from the ground point the weaker it gets. so its only a small area that the electrical current in the chassis would be able to interfere with the rca's. 
however when you run your rca's and your power wire next to each other for the whole 10-12 feet to the trunk... theres much more room for transfer of 'noise' from your power wire to your rca's.
the moral of the story is just run them on separate sides of the car. you have like 20-1 odds of not having any problems running your power and rca wires together.. (for a sub setup) but why not save your self the trouble and just run them on opposite sides to begin with.


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## pwnt by pat (Oct 21, 2005)

*Re: running rca & power wire together? (badb0ybilly)*

It's the same principle. Applied to my experiment, it would be the same as saying take the ground wire, run it to the chassis of the car, then back to the battery.
And actually the power isn't "dumped" to the chassis. It actually flows from the battery to the amp following the path of least resistanc which should be a pretty unform path.
As for current being reduced with distance: in order for a dc circuit to be complete, the sum of the energy put into the system must equal the total energy returned added to the energy outputted. increasing physical spacing between power and ground cables does nothing to affect the system's flow other than the possible increase in resistance due to the longer lengths of cable.

Running rcas opposite of power wire is purely has a cosmetic or astetic purpose. As long as remotely decent rcas are used (even the cheap-o radioshack rcas work perfectly fine) then they should be ran wheverer makes attaching them most convenient.
edit: Something else most people also forget: 
rcas are a dc-signal. the outside of the barrel is always a ground.


_Modified by pwnt by pat at 1:45 AM 4-2-2007_


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## run'nRabbit (Jul 8, 2006)

*Re: running rca & power wire together? (pwnt by pat)*

im a firm believer in keeping them seperate, also with my cars in the past what can go wrong seemed to go wrong







and i have had, on more than one occasion the motor whirring in my speakers and fixed it by seperating the rca's and power....


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## twelvevolt (Oct 29, 2003)

*Re: running rca & power wire together? (run'nRabbit)*

if you're using adequate rca cables, you won't have a problem. i've done it both ways and neither has had issues.


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## Selfmotivated24 (Jun 29, 2021)

pwnt by pat said:


> *Re: running rca & power wire together? (badb0ybilly)*
> 
> It's the same principle. Applied to my experiment, it would be the same as saying take the ground wire, run it to the chassis of the car, then back to the battery.
> And actually the power isn't "dumped" to the chassis. It actually flows from the battery to the amp following the path of least resistanc which should be a pretty unform path.
> ...


Correct me if I'm wrong but the power in the power wire would be stronger than what's leftover in the ground wire considering a lot of power is being used up in the speakers, or does speakers only consume the amount of power amplified from amp? But then again, power used doesn't come from thin air. It's all relative. So when the subs eat up power provided by the amp producing sound waves (which an amplifier could be named a converter instead of amplifier bcuz it converts DC to AC more so than it amplifies the source signal but regardless) the power that remains that goes thru the return line (ground) would be less then what the power wire endures. Bcuz if there were no alternator, the battery would eventually run out of power, it's not like 100% of the power in the power wire ends up going thru the ground wire, then a battery wouldn't die, right? I get that electrons are less excited at that point. *Kinda like after becoming married. Less excited.*


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## gtrev99 (12 mo ago)

Selfmotivated24 said:


> Correct me if I'm wrong but the power in the power wire would be stronger than what's leftover in the ground wire considering a lot of power is being used up in the speakers, or does speakers only consume the amount of power amplified from amp? But then again, power used doesn't come from thin air. It's all relative. So when the subs eat up power provided by the amp producing sound waves (which an amplifier could be named a converter instead of amplifier bcuz it converts DC to AC more so than it amplifies the source signal but regardless) the power that remains that goes thru the return line (ground) would be less then what the power wire endures. Bcuz if there were no alternator, the battery would eventually run out of power, it's not like 100% of the power in the power wire ends up going thru the ground wire, then a battery wouldn't die, right? I get that electrons are less excited at that point. *Kinda like after becoming married. Less excited.*





Selfmotivated24 said:


> Correct me if I'm wrong but the power in the power wire would be stronger than what's leftover in the ground wire considering a lot of power is being used up in the speakers, or does speakers only consume the amount of power amplified from amp? But then again, power used doesn't come from thin air. It's all relative. So when the subs eat up power provided by the amp producing sound waves (which an amplifier could be named a converter instead of amplifier bcuz it converts DC to AC more so than it amplifies the source signal but regardless) the power that remains that goes thru the return line (ground) would be less then what the power wire endures. Bcuz if there were no alternator, the battery would eventually run out of power, it's not like 100% of the power in the power wire ends up going thru the ground wire, then a battery wouldn't die, right? I get that electrons are less excited at that point. *Kinda like after becoming married. Less excited.*


Well, the power from the incoming 12V cables are actually not used in the amp like most would assume. In amplifiers, the DC voltage is used as "rail voltage", it is what provides the MOSFETs inside the amplifier with power. Amplifiers are essentially a set of biased MOSFETs/BJTs, that are setup to provide a gain to the signals coming in. The signal being amplified is in fact an AC wave coming from the RCAs themselves. The power cable is simply to "power" the amplifier and therefore, cannot introduce much noise to an AC wave coming from the RCAs. Yes, it can be argued that the harmonics coming from the alternator can affect those from the RCAs, but they are mostly eliminated from the rectifier after the alternator.


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