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Amp connections, ground loops, etc


crc

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Got a question for those cutty owners out there with non-stock audio systems.. How did you run the main power line from the battery to your Amp(s)? What path did you take?

 

Also, ground loops and noise.. I've noticed that I already have a somewhat poor radio reception now in my car and I want to get rid of all ground loop problems before I start putting in new equipment.. Any of you have problems with noise, alternator hum, etc?

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I ran a 4-ga wire through the clutch hole next to the column. It's a blank rubber plug, I slit an "X" in it and ran the wire through. It then snakes down into the wire channel along the driver side floor and right into the trunk to a splitter where it splits off into 2 8-ga wires for both amps.

 

I did have ground loop problems on my 4-channel amp. I was able to eliminate the ground loop simply by putting a ground loop isolator (available from Radio Shack) on the REAR RCA inputs of the amp, I did not need them on the FRONT inputs. Supposedly ground loop isolators may affect sound quality and the rears are just fill, so that's why I put it on the rear channels. No noise problems after adding the isolator.

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I ran a 4-ga wire through the clutch hole next to the column. It's a blank rubber plug, I slit an "X" in it and ran the wire through. It then snakes down into the wire channel along the driver side floor and right into the trunk to a splitter where it splits off into 2 8-ga wires for both amps.

 

That wire channel, did you have to take apart anything to get at it? What was in the way?

 

I did have ground loop problems on my 4-channel amp. I was able to eliminate the ground loop simply by putting a ground loop isolator (available from Radio Shack) on the REAR RCA inputs of the amp, I did not need them on the FRONT inputs. Supposedly ground loop isolators may affect sound quality and the rears are just fill, so that's why I put it on the rear channels. No noise problems after adding the isolator.

 

That was the first option I thought about doing and I might end up buying that thing... It still won't solve the noise problems i'm having with my radio.. For example if I hit my brakes I get a 'pop' in the radio reception.. Just drives me nuts.. I've checked the antenna ground, and another ground in the Instrument Panel.. There's a third one that snakes back to the headunit ground wire and that I believe that is somewhere near the direct ignition module on the engine block.

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I had to remove the plastic trim that runs along the bottom door opening to get to the wire channel, but I think that's it. I was able to snake it along in the channel without much problem.

 

I don't know what could fix your noise problem, but a ground loop can cause lots of crazy noise problems so you might try that isolator, who knows, it might get rid of the popping too (I seem to remember mine may have popped as well).

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Most noise comes from poor grounds.. at least that's what it was in my lumina, and now in the Cutlass. I know I had some nasty noise in the system when I first put it in to the cutlass. Turned out the be a poor ground connection on my EQ. Re did the connection and it's silent now..

Some noise can come from low quality 'unshielded' RCA audio cables. I run all 'Streetwires Musica 200s' with my system, so I'm pretty sure that helps. Power cables run down the drivers side of the car, RCA audio cables down the center of the car, and speaker wires down the passenger side. Though

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and here i thought i was the only one running old school things. i too am running musica 200 rca's from HU to each amp.

 

i too did the same as mentioned in running the power wire from front to back. be verry sure to secure everything well. this means power and ground wires. be sure to upgrade the ground at the batt to frame.

 

i forget if there are any pics on my site on where the wires run down the sides.

 

Monty

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i find alot of noise on mine, and am figuring on re-running my cables... i cant run the rcas(monster cable xtra low noise 2) down the center cause i dont wanna pull carpet or anything. im running power,rca's, and front left speakers down the driver side, and front right down passenger. i can get pics if anyone wants em, i have a digicam ready. i also have a custom mount for my front/rear amp. i just need to carpet the board and itll be awesome.

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I think the noise on mine is mostly coming from an actual ground loop.. I just grabbed an isolator today from an audio shop. It has RCA connections for low-input. I just don't want to get into that whole thing of tracking ground paths inorder to break the loop and stop the alternator noise.

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  • 2 weeks later...

it is highly recomended to run the power wire as far from the rca's and speaker wires as possible as the power will introduce noise into the system.

it is common place to run the power down the same side as the battery as that provides the straightest shot from batt to firewall.

and then run rca's and speaker down the opposite side of the car. yes this requires you ro remove both sides trim panels but it is worth it as this reduces the chance of noise in the system. also make sure the grounds are secure and metal to metal contact is made. for the amp ground and upgraded batt to frame ground this means scraping or using a wire wheel to get down to bare metal. there are silicone based sprays to spray that area afterward to reduce rust and corrosion.

 

Monty

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I always prefer to use existing bolts for grounds. There are some pretty hefty bolts/studs you can use near the trunk that are used for seatbelts, seatbacks, etc. I think I just used the power antenna ground, but I'm only using a small 8GA wire.

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if possible it is good to use existing grounds as you know they are solid, but it is also best to keep ground wires as short as possible. with that in mind using existing is not always a possibility.

 

there are spots in the cutty trunk that work great. on the seat back and rear deck are many holes that can work.

in previous rides there were lips on the rear corners of the trunk floor that i could drill a hole in and bolt the ground there after some paint removal. all from the top side. have also done the drill through the trunk thing and took two ppl to secure the ground.

 

Monty

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Yup yup, I agree on the RCA routing thing. I always stripped my interior completely when I did the main wiring. I ran the RCAs on one side of the car and made every effort NOT to cross ANY wires over it our with it or around it. I also always used gold connectors (though I highly doubt that will make a huge difference. Definately spend the money on EXCELLENT RCA cables. I have almost always used Monster Cable RCA's, but have used RF cables as well (white wolf? I forget which, they are pearl white in color, chrome ends). I usually ran two amps, sometimes a single (ADS 6-channel). For the poer, I used 4gauge, and for the main ground, I also used a 4guage. I used distribution blocks for the power and grounds, then used 8guage to actaully send power to the amps from the distribution block. Same went for the grounds. I think my ground wires were never longer than a foot and a half. One of the best sounding, least noise filled (had absolutely NONE) was when I experimented by sending a second ground wire to the main ground connection in the trunk for my head unit. It hooked right up with the 4guage connection (I used 16gauge wire for the head unit ground. I baffled professional installers and my friend when I did it, but it was noticably cleaner than his audio system. The pro installers shook there head, they swore there should have been noise. HEH! I don't know if it would always work, but hey, it did that time.

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the profesional installer should have already known that running the HU ground to a common ground point would work well. i have seen ppl do the same for the HU power as well. and then use the memory wire from the factory harness.

dblocks are nice but only needed if multiple amps are being used. or if you just wanna run wire one time in case you add more amps later or redo the setup. much easier to hook up to a dblock rather than removing things to get to the hidden ground points.

 

i have always stayed clear of this and always made sure wires did not cross, but if they do then i have been told to be sure to cross them at right angles to each other. this reduces the chance of induced noise.

 

as far as RCA's go i have been told there is no need to go extravagant on them. simple twisted pair is sufficient. this is where the wires are twisted together in one jacket. they are usually only a few more bux than standard rca's. where the wires run side by side no twisting.

since mine work fine i will stick with them for now. never had any noise issues in any of my installs. guess i got lucky. :)

 

Monty

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And here's why twisted pairs work so well..

 

It has to do with the magnetic fields the wires create when they have electricity running through them. When you twist 2 wires together you basically cancel out the magnetic field between them. This is because the two wires that are twisted together are usually part of the same circuit...ie ground and signal. Anyone remember the right hand rule of magnetivity?

 

I have a $5k system in my car (shh, don't tell anyone)...which includes fiber optic/S-Video/RCA/Coax cables. I used the best wire possible throughout the install. I used the twisted pair cables, and they work great. If they work for a $5k install, they should work for you.

 

(Can't tell that I'm bored, can you?)

 

Jason

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same here......i failed them, but that was one of the few things i paid attention to. i needed the classes for credit purposes only, not for what my guidance dept wanted eveyone to do and go into the networking fields with a CCNA (which i hear from some people isnt worth a shit)

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