Ground loop isolators?

[DJ Hellfire]

Ever since I added an external cross-over unit to my audio system to use with my interior speaker amp, I have the dreaded ground loop. It's grounded to the same point as my amps and cap but it's still buzzing. I think it's because my HU has 5 volt pre-outs and the cross-over has 6 volt preouts. So there is a lot of power going through the RCA's. If I lower the gains on the cross-over and amp, the loop amost goes away, but then my subs are much louder than my interior speakers.

I tried grounding the RCA wires which didn't help much. So now what I am going to try is to connect my rear main ground with all the equipment on it to the same ground as my head unit so every piece of stereo equipment in my car has the same ground, even the cig lighter (ipod charger makes hella noise). This means running a long-*** ground wire from the front to the back. I believe this will work, but if it does not, I need to buy a couple of isolators. Is any one better than the other? I can get two on ebay for $15 shipped or go to a store and spend over $60. Are they all pretty much the same? My shiznit is VERY crisp, and I do not want to lose an ounce of audio quality. But they all say no loss in audio quality. Sounds hard to believe. Any recommendations?

[cclngthr]

It is easier to put a ground loop filter between the amps and the head unit. On my car, I have the stock HD head unit that has the aux jack and if I have the aux devise hooked up to the power outlet, I get wine. What I did was put the ground loop behind the dash between the deck and the jack between the power outlet and cig lighter.

[hyunelan2]

Also, make sure your RCA wires are ran differently than your power wires, not sitting on top of eachother.

[DJ Hellfire]

Also, make sure your RCA wires are ran differently than your power wires, not sitting on top of eachother.

I got that. I've been installing for years and my system has been in for years. I just never had a wine until I added the cross-over a couple months ago! I've never had a need for an isolator in any of my installs. It's just something about this cross-over unit! So is a more expensive isolator any better than a cheaper one?

[cclngthr]

What happened is the crossover is creating a mini-ground, creating a feedback. Try removing it to see if you get noise.

A GLI is a good idea because it filters out what you don't need in the audio system.

[DJ Hellfire]

What happened is the crossover is creating a mini-ground, creating a feedback. Try removing it to see if you get noise.

A GLI is a good idea because it filters out what you don't need in the audio system.



Like, I said, I got the noise when I added the x-over about 4 months ago. If I bypass it and run the RCA's directly to my amp, I have no noise. That's how it was for years. But my interior amp's x-over is not adjustable. You can only switch between LPF, HPF, and Full. It has no frequency adjustment which is why I added the external x-over. This boosted my preout voltage to 11v from 5v. But will any GLI do the job, or are there more quality ones than others?

Alright, earlier, I tried connecting everything to 1 common ground. The noise was still there. So I just went to Walmart and picked up a couple of GLI's and the noise is still there. I wonder if the x-over is bad or if I need better RCA's or just a new alternator! It seems like the noise is better with the GLI's, but the noise always nearly went completely away once the car get's driven for a few miles and get's warmer; so that also can be why the noise seems better now. This makes me lean more towards the alt. So I'll have to recheck it in the morning when it's cold. The only way I know of to get rid of the noise now is to get rid of the x-over, but I lose that sound I want.

[cclngthr]

It is possible that the x-over is bad. Normally that wouldn't happen. I think the x-over is grounding the audio signal wrong. Usually, speaker wire is a 4 conductor or 3 conductor setup (the 3 conductor uses a common ground). If by chance the x-over grounds out the speaker lead wrong, it could cause the whine.

I don't think it is the alternator that is causing the excess noise.

[furcioelbravead]

i had the same problem when i added a new clarion hideaway brain to the car and i got ridof the problem by simply grounding the rca's in the brain and then connecting the rcas normally, check the crossover, that problems is caused by the components, not by the alternator or anything like that.

[carchick78]

It does seem like you have a lot of audio hooked up and one thing that I did learn in school is that when you have that much connected it can be the alternator. Check that out and see what happens if you didnt already.

[DJ Hellfire]

Well, my alternator works properly. The only reason I suspected the alternator is because the noise goes away after the engine is warmed up. It seemed like the alternator needed to get warmed up. But I guess that could be the same for the cross-over too.

Anyway, I added a couple of GLI's and it helped for the most part. It's still not 100%, but much improved!

[kizzo]

It'd be a better idea to switch out the crossover. If you've narrowed it down to the crossover being the root of the noise problem then focus on fixing that, avoid patching it up with a GLI.

[DJ Hellfire]

It'd be a better idea to switch out the crossover. If you've narrowed it down to the crossover being the root of the noise problem then focus on fixing that, avoid patching it up with a GLI.


You know, I'm not sure that there is a problem with the cross-over. I have a strong feeling that if I were to replace it, the new one would do the same thing. I think the noise is due my my 5V pre-out radio going into the 6V pre-out x-over. Doesn't that make a total of 11V of pre-outtage going into my amp (twice)?

[cclngthr]

You know, I'm not sure that there is a problem with the cross-over. I have a strong feeling that if I were to replace it, the new one would do the same thing. I think the noise is due my my 5V pre-out radio going into the 6V pre-out x-over. Doesn't that make a total of 11V of pre-outtage going into my amp (twice)?

That is possible, however it could be that you only have 5 volts running to the amp. I doubt that the x-over increases the voltage any. It may be possible that the 5 volt signal is allowing enough static to run through the system because you have a 6 volt x-over. If your x-over was a 5 volt system, I doubt you would get the excess noise. Here, I mean the voltage capacity from the x-over is allowing the static to feed through the system because the capacity is higher than the signal going to it.

[DJ Hellfire]

That is possible, however it could be that you only have 5 volts running to the amp. I doubt that the x-over increases the voltage any. It may be possible that the 5 volt signal is allowing enough static to run through the system because you have a 6 volt x-over. If your x-over was a 5 volt system, I doubt you would get the excess noise. Here, I mean the voltage capacity from the x-over is allowing the static to feed through the system because the capacity is higher than the signal going to it.

Yeah, if I set the gains between the x-over and the amp low enough, the whining will go away, but then the overall volume is not as loud as it can be. With the GLI's, I was able to bring my gains up a bit more with very minimal whining. Normally, I keep my gains a bit below the 1/2 way mark (setting it with a volt meter is too time consuming). But with the x-over, I had to go even lower on both the amp and x-over in order to limit the noise.


Also CC, in the manual it says for troubleshooting whining, make sure the HU and x-over are grounded at the same point. I have already done this and still got the noise. What I did was grounded the cross-over to the same point as the amps. Then grounded the radio inside the dash. Then I ran a 14 guage wire from the radio ground point to the x-over/amp ground point. You thing 14 guage was sufficient enough?

[cclngthr]

Yeah, if I set the gains between the x-over and the amp low enough, the whining will go away, but then the overall volume is not as loud as it can be. With the GLI's, I was able to bring my gains up a bit more with very minimal whining. Normally, I keep my gains a bit below the 1/2 way mark (setting it with a volt meter is too time consuming). But with the x-over, I had to go even lower on both the amp and x-over in order to limit the noise.


Also CC, in the manual it says for troubleshooting whining, make sure the HU and x-over are grounded at the same point. I have already done this and still got the noise. What I did was grounded the cross-over to the same point as the amps. Then grounded the radio inside the dash. Then I ran a 14 guage wire from the radio ground point to the x-over/amp ground point. You thing 14 guage was sufficient enough?

Electrically, (I employ a certified electrical tech and have asked him) there is some feedback that gets through the x-over even if the x-over and other audio equipment is grounded at the same location. Static will feed through if the signal voltage is lower than the capacity of the other components and IF the receiving end (amp) sees the static as the normal signal that is up to the limit of the units limit voltage. Using the same ground pount reduces the chances of the feedback coming through, but it won't eliminate it totally. You grounded the radio and x-over in more than 1 spot. You essentially have multiple grounds instead of 1. To ground them in 1 spot means eliminating the multiple ground points (which also means cutting wires) and running the amp, x-over and radio ground into 1 wire. Here, a 8 gauge or bigger wire to each unit is necessary (otherwise, you get feedback) and putting that on a ground bus system and grounding that to the chassis.

Wayne thinks that the signal source is most of the problem. The 6 volt capacity of the x-over is allowing feedback to come through because the signal source voltage is lower. He also thinks the x-over ground should be at the radio (by running a ground wire from the radio harness to the x-over).

[DJ Hellfire]

Alright, I' might try it. If I do, I'll let you know if it works. I've had my dash apart numerous times last week chasing this noise and it's annoying.

[cclngthr]

Let me know.