Do speaker wires near RCA's cause engine noise?

[MikedaPimp]

I know you are supposed to run the power and RCA wires down opposite sides of the car, but can you run speaker wires down both? Can you only run them next to the power, or only next to the RCAs, or doesn't it matter? Thanks. ~Mike 98.5 2.8MS 30v Silver/Black

[siberian]

because the current is relatively low on both accounts. It's the power wire you have to worry about cause the current is much higher, creating a more intense electro-magnetic field around it. That magnetic field is what causes the noise.

However, given the rule of Murphy's law, I guess anything is possible.

If I were you I'd just error on the side of caution and run the RCA's down the center, and speaker cable down the passenger side.

Also, use good RCA's that AT LEAST utilize twisted pair construction. This helps reject noise. If you can get twisted AND shielded, that's even better. I used Stinger Dream series.... twisted, and shielded. Got'em at Sounddomain.com for pretty cheap. Great cables but a little fat on the o.d.

[MikedaPimp]

What about running the *speaker wires* down the center? Or will that be more of a pain in the ***? I think Mark told me he ran power down left side, speaker wires down left side, and RCAs down the middle and he has a little engine noise. So I figured getting the RCA's as far from the power wire as possible would be a good idea. Yes, no?

~Mike
98.5 2.8MS 30v Silver/Black

[MoBrazen]

Run them down OPPOSITE sides of the car! Pain in the butt, but well worth it.

[siberian]

you said he ran power and speaker down the left.... I think you meant speaker down the right..... right? Anyway if you had to choose between running the speaker or the RCA's closer to the power... I'd pick the RCA's because they are more readily available with noise rejecting capability.... (as I mentioned, twisted and/or shielded cable helps block noise from getting in) whereas speaker cable generally comes in basic parallel construction and not shielded. So, between the RCA and speaker wires, chances are better that the speaker wire could pick up noise if you run it closer the power cable. As for why he has noise, there are other sources of noise besides your speaker and signal cables too. For example, a poor ground connection can cause all kinds of problems. Also, if the amp has the power and speaker and/or RCA cable jacks all next to each other, then that forces you to put the cables near each other. That's why I look for amps that have the power and ground connections located AWAY from the speaker and RCA jacks.

Here, I did mine this way.... I have the 4ga power on the driver side, three sets of RCA's and the CD changer cable down the center hub (front and rear channel on the passenger side of the center hub, and non-fading subwoofer output and cd changer cable on the drivers side of the center hub) Then I ran the speaker wire down the passenger side of the car. At the back seat the RCA's join the speaker wire and run along side each other up the rear passenger side bolster into the trunk. And at one point under the drivers side dash, the speaker wire for the drivers side door (two 12ga cables) crosses the 4-ga power wire about a foot away. However this is not a problem because if you cross cables at perpendicular angles to each other, that also helps prevent magnetic noise coupling. It's when you run them parallel that can cause problems. Anyway, in my car I have ABSOLUTELY ZERO noise....ZERO! Not a single peep... not even a HINT of a peep. It's dead silent... even when I turned the gains up on the amp past the point where they would normally be set.... just to see if it would give me any noise. Still no noise. None.

[MikedaPimp]

I don't get how you can run speaker wires from the drivers side over to the passenger side. They are going to cross right over the power wire, right? But you said perpendicular is not as much of a problem.... And I am going to have two 4awg power wires running down the drivers side (2 amps). Where exactly did you run the speaker wires from the driver's side doors to the passenger side? I was thinking for the front door, just take out the front seats and run them under there. For the rear run them under the rear seat? Would this work? Thanks.

~Mike

~Mike
98.5 2.8MS 30v Silver/Black

[siberian]

I ran four sets of speaker wires from under the back seat (where I have my Diamond crossovers located under the seat cushion)down the passenger side of the car to the front foot well. Two wires were fed into the passenger door harness. The other two were run under the carpet (up high behind the glove box) and over to the drivers side of the center hub. At that point I fed the cable up under the dash to keep it elevated as far as possible above the power cable which enters the cabin through a grommet just behind the clutch pedal and runs down along the floor under the carpet then behind the kick panel, then under the door sill towards the back seat. Okay, so now I have the speaker wires running just below the steering column (again, keeping them distanced from the 4-gage power as much as possible), then over to the side wall of the car and dropped down to where the existing wire harness enters the drivers side door.

Basically, the power cable is kept as low as possible (the floor) and the speaker wire is kept as high as possible (under the dash) and so the closest they come to each other is maybe about a foot.... which is the approximate height of the door grommet off the floor of the car. And when they do cross, they are perpendicular... since the power cable runs front to back, and the speaker cables run right to left.

Make sense?

Like I said, here are some other factors that help reject noise....

I have 4.5 volt pre-amp output on the head unit. The higher the output voltage, the better noise rejection potential. Many aftermarket head units have less, like 2 Volts.

Shielded and twisted construction RCA cables. I used Stinger Dream series. It's their best top of the line RCA cable... 16-footer's were like $29 bucks each from sounddomain.com. Great price compared to the Phoenix Gold cable, and just as good in my opinion.

No extra slack in the RCA's. I carefully measured my cable path before buying the cable and bought just the right length with hardly any slack left over. This meant that I didn't have to coil up any extra cable slack.... which is another potential noise maker.

Good ground contact. I got lucky and found a ground point on the chassis that doesn't cause ground loop problems. I used the bolt on one of the back seat belt anchors.

And that's about it. That's my story and I'm stickin' to it!

[siberian]

but if given the choice between running either the RCA's or the speaker down the center, I'd rather use better RCA's that reject the noise 100% than take the chance of the speaker wires picking up a little noise... since speaker wires have little if no noise rejection capability anyway. If the RCA's don't allow any noise to enter, then the amp can't amplify a noise that isn't there to begin with.

right?

I suppose there are many ways to do it and have it work... this is the way I did mine, and it works great.

[MikedaPimp]

Do you remember how long your RCA cables were? I would be running the same path as you, from dash, down the center, into the trunk, where I am building some kind of amp wall. Also, about how much speaker wire did you use? Just to get an idea so that I don't buy a whole bunch I don't need. I was going to go with 12ga for everything. And my head unit has a 4.8V max output.

Also, since I am running two 4awg wires...will they both fit through the grommet behind the clutch pedal? Do I need to ground them to the exact same spot? Someone mentioned this before, just making sure so I don't screw anything up.

~Mike
98.5 2.8MS 30v Silver/Black

[siberian]

my RCA's I think were 16 foot'ers. I had JUST enough slack. Mine come out of the trunk on the passenger side, and the amp I'm using will be mounted so that the RCA inputs are located on that side of the car. So be careful.

Speaker wire.... aw geez, I can't remember how much I used..... it's been awhile. I do know that I started with 50 feet. Then I ran out and had to order I think 20 or 30 more feet. I ran two sets from the amp in the trunk to the crossovers in the back seat tub. From there, four sets to the front of the car- two into the passenger door, two into the driver side door. Also, I wired a couple of feet directly to each speaker and employed an in-line... quick disconnect connector so that I could take the door panel off in the future without having to cut the wires.

I have a couple of feet running from the amp direct to the sub box as well. Mind you, don't have rear speakers right now, so I'll need to order another few feet when I eventually get the rears.

I'd say total, I'll end up using about 80 to 100 feet.

The best way to plot out is to take a piece of string and have someone help hold it in place while you run it along your intended cable path. Then measure the string when you're done. Write everything down and double check your calculations. Then add a few extra feet on top of that to make up for f*ck-ups.

The grommet behind the clutch pedal had a few open spaces in it. So it probably won't be a problem. When you poke it through, take a phillips screwdriver or someting sharp to poke a hole in the rubber first.... then wet the cable end with spit, and push it through (from inside the car) and is should go.

There are conflicting theories as to where and how you should run multiple ground wires. I put mine on the same point. For now I'm only using one amp, however I pre-wired everything for two amps. Just make sure you use the same gage ground wire as your power.... which in your case would be 4 gage.