Unwanted Noise...Knu Conceptz?

[fatryan 5,000+ posts]

I just installed my Merlin MD2, L7s, Orion 500.4, and 3 pairs of Knu Concepts top of the line RCAs (Krystal Kable i think). Well the old RCAs i had were some low end crappy RF ones. And now, i got a TON of unwanted noise. I hear a loud hissing sound all the time. What could it be? Are Knu Koncepts RCAs crap? Could it be the Orion? //content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

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[Oak244 10+ year member]

Usually a ground loop of some kind is the trouble maker.. Try disconnecting each component one at a time and see if one stops the noise. If it does, try grounding it somewhere else.

 

[knukonceptz 10+ year member]

As I mentioned in my email, disconent the RCA's at the HU. If the noise is gone its a ground loop coming from the HU. Noise being "absorbed" by the cable is one thing, having it already in the signal is another.

The RCA ground is probably connected by some circuit in the Orion. The difference in voltage between the HU and amp in turn cause the noise. Another forum member explained this really well a day or two ago, I'll see if I can locate that post.

 

[fatryan 5,000+ posts]

As I mentioned in my email, disconent the RCA's at the HU. If the noise is gone its a ground loop coming from the HU. Noise being "absorbed" by the cable is one thing, having it already in the signal is another.
The RCA ground is probably connected by some circuit in the Orion. The difference in voltage between the HU and amp in turn cause the noise. Another forum member explained this really well a day or two ago, I'll see if I can locate that post.

so its my HUs ground? that doesnt make sense. i never changed that ground at all when i took out my 300/4

 

[knukonceptz 10+ year member]

Here ya go, its a combination of amp/HU:

Classic ground loop symptoms. The HU and amp grounds are at slightly different potentials. The RCA cables connect the grounds together by nature of their shield wire. Each RCA you plug in reduces the resistance and at some point the RCA ground path is lower than the wire ground path and noise happens. That's been my experience, anyway. Maybe it's the phases of Jupiter's moons. At any rate, I feel your pain... my system does the same thing.
Yes, some amps are more sensitive to this than others. Some HU's too. Amps with well designed input circuits where the RCA jack is isolated from chassis ground are more immune to ground loops. My USX 4065 and Pioneer HU combo does exactly what you describe.

Solutions vary. Relocating the HU ground often does it. In my case it doesn't matter because the HU chassis is grounded to the metal dash and the ground wire don't do ****. Using "directional" RCA cables (with the internal shield disconnected from one end) worked for me. Last resort is ground loop isolator thingies on the rear channel RCA's.

Good luck. Noise sux.

 

[fatryan 5,000+ posts]

Here ya go, its a combination of amp/HU:

Im still confused, lol. what should i do again?

 

[knukonceptz 10+ year member]

Ok, you have noise. We need to see where it comes from. One part of the system is making the noise. Is the noise in one or all amps? The easiest place to start is at the amps. Unplug the RCA;s at the amp ( with radio off) Turn on radio, any noise? No - well you eliminated the amps and anything after them - plug back in.

Go behind the HU and unplug the RCA's there? Any noise? No...You only added RCA's and still no noise. Plug in the radio, Noise? No??....lay off the drugs... //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

er...Yes...ground loop, the voltage difference(resistance) between the two components causes the noise. Running a ground and power wire from HU to amp distribution block will eliminate this as it should even out the difference in voltage

 

[fatryan 5,000+ posts]

Ok, you have noise. We need to see where it comes from. One part of the system is making the noise. Is the noise in one or all amps? The easiest place to start is at the amps. Unplug the RCA;s at the amp ( with radio off) Turn on radio, any noise? No - well you eliminated the amps and anything after them - plug back in.
Go behind the HU and unplug the RCA's there? Any noise? No...You only added RCA's and still no noise. Plug in the radio, Noise? No??....lay off the drugs... //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

er...Yes...ground loop, the voltage difference(resistance) between the two components causes the noise. Running a ground and power wire from HU to amp distribution block will eliminate this as it should even out the difference in voltage

ok i will check tommorrow. thanx

 

[knukonceptz 10+ year member]

No problem, let us know what you find

 

[fatryan 5,000+ posts]

will do

 

[fatryan 5,000+ posts]

i havent gotten around to checking it(ill do it tommorrow for sure), but i got a new problem today, lol. first, my brand new eclipse 8445's screen shut off! WTF? but its under warranty. then later tonight i started to get engine noise from the speakers. it whistled, then when i reved the engine, the whistle got louder. b4 i check the wires and stuff tommorrow, does this new info mean anything? thanx

 

[alteraudiousa 10+ year member]

bad grounding spot if you're getting engine rev noise.

 

[fatryan 5,000+ posts]

bad grounding spot if you're getting engine rev noise.

ok. ill reground tommorrow then

 

[96civ 10+ year member]

I dont know if this will work, but would it help for him to add a resistor to the path with the higher resistance? Or would it just be easier to add a distri box like you said?

 

[White Rascal 10+ year member]

Here's a good source of info on how to track down unwanted noise in your car's system...

Noise Elimination

Pay particular attention to the part that discusses "muting plugs" in section 8.1. I've used them on many occasions to track down noise problems in cars.