bad to run signal wire with power wire?
11-20-2009, 03:52 PM
#11
500 Watt CAFz'r
Join Date: Oct 2009
Posts: 730
Hey, I don't disagree with anything that you have said aside from "NEVER". And as for the BB/FS comment I made, I come from a BB install bay, so I know about the backyard bashers myself.... They aren't the ones purchasing the kits that have the proper cables, but they manage to show up in the bay with issues.... Who knew?
11-20-2009, 04:23 PM
#12
500 Watt CAFz'r
Thread Starter
Join Date: May 2007
Posts: 849
Dukk you are incorrect, I did not get an alternator whine before the amp kit was installed. I could hear the whine AFTER it was installed.
The RCA's were taped together with the 8awg wire going through my car.
It was a stinger 8awg kit.
Just next time, I will make sure to have it routed on the other side of the car just in case!
The RCA's were taped together with the 8awg wire going through my car.
It was a stinger 8awg kit.
Just next time, I will make sure to have it routed on the other side of the car just in case!
11-20-2009, 04:29 PM
#15
500 Watt CAFz'r
Join Date: Oct 2009
Posts: 730
Isolate the problem. Pop out your head unit and plug in a seperate set of RCA's. Just run them between the seats into the trunk to your amp. If you have no noise, it's the RCA's, still have noise, it's not. I'd check ground(s) at this point. RCA's aren't typically the issue, like Dukk said, and if it is it's due to unfit or damaged RCA's.
.
11-20-2009, 05:15 PM
#17
50 Watt CAFz'r
Join Date: May 2008
Posts: 365
why not test this next time you do an install?
simply run the rca's with the power wire and have another set ready to connect while testing, but this second set just lay across the seats to the amps and see what happens!
i have mine run separately and still have some noice that can only be heard when the volume is turned down or no music is playing. i have not finished my big three though and am hoping will disappear when i finish off the grounds. my amp grounds are frame grounds but the stock grounds on my truck are those loose wire flat type that manufacturers luv to use. not the best and not protected from the elements.
gl
simply run the rca's with the power wire and have another set ready to connect while testing, but this second set just lay across the seats to the amps and see what happens!
i have mine run separately and still have some noice that can only be heard when the volume is turned down or no music is playing. i have not finished my big three though and am hoping will disappear when i finish off the grounds. my amp grounds are frame grounds but the stock grounds on my truck are those loose wire flat type that manufacturers luv to use. not the best and not protected from the elements.
gl
11-20-2009, 08:14 PM
#18
Yankee
Join Date: Oct 2003
Posts: 3,599
mutual inductance, is where wires side by side induce a signal into the other, this is described in Faraday's Law with Lenz's Law defining the amount of mutual inductance and the direction of EMF and CEMF and this is called several things including eddy current but it is the basis of transformer or motor behavior. The requirements for mutual inductance IN THIS SITUATION are a pair of complete circuits capable of conducting current and a varying magnetic field between the two. DC is not a varying signal so it has little capability to induce current (power wire next to a signal carrying wire)... but a varied signal (AC) can induce into another varied signal (AC) this means speaker wire can affect another speaker wire OR a RCA. So running wires along side another wire CAN cause issues, if a DC wire is involved it has little capability to induce audible noise (transformer action if you will) but it can apply a small system bias voltage in some circumstances (far fetched if you will).
RCA signals are wimpy, with low voltage signals and only milliamps of signal, and that makes them sensitive to mutual inductance... EMI and RFI. The best way to stop RFI is with a shielded conductor or even a coaxial cable. But RFI really isn't much of an automotive issue so shielded cables are something between overkill and shinola (sp?). EMI is an issue with strong magnetic fields and relay circuits that make and break contact (fluctuating magnetic fields will induce current in RCA's), door open buzzers and electronic devices are common sources of induced noise and you have to reroute the cables away from these sources of noise as using a grounded shield (tin, lead or even aluminum) will have minimal affect. The best protection is distance from the noise source and the use of twisted pair/ braided wiring in your RCA and speaker wire. Twisted pair (or braided) wiring exposes the + and - signal equally to the offending EMI thus inducing a minimal and equal induced signal in each phase. The net noise induced therefore is minimal (theoretically zero).
short version:
- power cable next to signal cable: hard to induce noise (and if it did it would be a bum or an inaudible bias voltage) not an alternator whine
- Speaker cable, AC cable or even a turn signal cable next to an RCA could induce noise
- Braided cables are better for automotive noise rejection in most situations than shielded or coax
- Shielded and coaxial cables are useful in minimizing RFI or noise from electronics/ computers
RCA signals are wimpy, with low voltage signals and only milliamps of signal, and that makes them sensitive to mutual inductance... EMI and RFI. The best way to stop RFI is with a shielded conductor or even a coaxial cable. But RFI really isn't much of an automotive issue so shielded cables are something between overkill and shinola (sp?). EMI is an issue with strong magnetic fields and relay circuits that make and break contact (fluctuating magnetic fields will induce current in RCA's), door open buzzers and electronic devices are common sources of induced noise and you have to reroute the cables away from these sources of noise as using a grounded shield (tin, lead or even aluminum) will have minimal affect. The best protection is distance from the noise source and the use of twisted pair/ braided wiring in your RCA and speaker wire. Twisted pair (or braided) wiring exposes the + and - signal equally to the offending EMI thus inducing a minimal and equal induced signal in each phase. The net noise induced therefore is minimal (theoretically zero).
short version:
- power cable next to signal cable: hard to induce noise (and if it did it would be a bum or an inaudible bias voltage) not an alternator whine
- Speaker cable, AC cable or even a turn signal cable next to an RCA could induce noise
- Braided cables are better for automotive noise rejection in most situations than shielded or coax
- Shielded and coaxial cables are useful in minimizing RFI or noise from electronics/ computers
11-21-2009, 12:50 PM
#19
50 Watt CAFz'r
Join Date: Nov 2009
Posts: 54
Quality RCA's do make a difference.
A while back I had to go out and buy a replacement RCA and immediately noticed engine noise.
However, when I tested with a cheap VCR (red/white) set I had lying around to diagnose the issue I had no problems.
Some RCA's do perform better than others, and typically it's not reflective on their price.
A while back I had to go out and buy a replacement RCA and immediately noticed engine noise.
However, when I tested with a cheap VCR (red/white) set I had lying around to diagnose the issue I had no problems.
Some RCA's do perform better than others, and typically it's not reflective on their price.
11-21-2009, 10:15 PM
#20
Administrator
Join Date: Feb 2006
Posts: 16,855
Dukk you are incorrect, I did not get an alternator whine before the amp kit was installed. I could hear the whine AFTER it was installed.
The RCA's were taped together with the 8awg wire going through my car.
It was a stinger 8awg kit.
Just next time, I will make sure to have it routed on the other side of the car just in case!
The RCA's were taped together with the 8awg wire going through my car.
It was a stinger 8awg kit.
Just next time, I will make sure to have it routed on the other side of the car just in case!
