Ground Loop

dwnrodeo · Post by **dwnrodeo** » Sat Sep 11, 2010 11:20 am

I am getting quite fed up with a persistent ground loop that is present in my new install. My setup is as follows: Kenwood X994 headunit front output to EQ215X. From the EQ, I have the highpass going to an XS2300 which powers the tweeters. The lowpass ouput from the EQ is going to an XS4300 which powers the mids. The Kenwood rear output is going to an XS2300 which powers the door woofers. The Kenwood sub output is going to an XS2500 which is off at the moment. The headunit and amps have power wires going straight to the battery. The EQ and amp remotes are going to a DD5 which is wired straight to the battery. Everything has a positive and ground wire straight to the battery. All amps, EQ, DD5, are isolated from the chassis.

Now... I had this ground loop before (alt. whine) and found the EQ was grounding to the chassis. I isolated that and it was fine. A couple days later, I re-installed my rear seat and trim panels and the noise (alt whine) came back. It wasn't bad, but still audible. Yesterday I had new tires put on the vehicle and when I got it back the noise was unbearable driving down the road. I pulled the back seat and trim panels and still had the noise. Swapped RCA's and still had noise. Pulled the EQ and ran an RCA from the headunit to the tweeter amp and still had noise. Replaced the tweeter amp with another amp and still had noise.

I even unplugged the RCA's from the EQ, left them plugged into the tweeter amp and had noise. I could even faintly hear music coming through the tweeters despite no RCA's hooked to the EQ! Now I don't even have to have the vehicle running, just having the key on right before you start it will produce a horrible whine. The only way I could get no noise was to plug my ipod directly into my tweeter amp or have no other electronics on in the vehicle, just the headunit.

Does anyone know if the Kenwood has issues like the Pioneers regarding pico fuses? I'm at my wits end here and just want this to go away.

The Golden One · Post by **The Golden One** » Sat Sep 11, 2010 11:55 am

i think there could be a posability that one of the speaker wire's could be picking up noise if it's close to the computer or even a power wire. also if your factory amp is still hooked up it maybe emitting noise there are many posability's. you could try running some temporary wire to the tweeter's away from every thing electrical and move them around to see if the noise is still present.

dwnrodeo · Post by **dwnrodeo** » Sat Sep 11, 2010 12:19 pm

The speaker wire is close to the power wire, but I'm not sure that is the issue. I just went out in the garage and tried it again. I can remove the tweeter RCA's completely from the EQ and still have noise. If I unplug only one of the midrange RCA's, the noise will also come from the mids. If I unplug all of them, it stops. I will try moving the tweeter wire, but I feel there is another issue causing this.

Post by **ttocs** » Sat Sep 11, 2010 12:30 pm

where is the eq mounted?

how did you set your gains? have we tried turning them down yet?

dwnrodeo · Post by **dwnrodeo** » Sat Sep 11, 2010 12:59 pm

The EQ is mounted under the steering column. The gains were set using an o-scope. I haven't adjusted the gains since.

Post by **ttocs** » Sat Sep 11, 2010 2:33 pm

is its chassis grounded?

You are not running passive crossovers either right?

dwnrodeo · Post by **dwnrodeo** » Sat Sep 11, 2010 3:16 pm

Nope. The EQ is removed from the vehicle right now and I still have the noise. No passives, all active.

The Golden One · Post by **The Golden One** » Sat Sep 11, 2010 3:43 pm

if the head unit gets it power from the fuse box it could be a source for noise because being in the same path as the onboard electronics can introduce noise. also if the frame of the headunit isnt grounded you may try to ground it and even ground the rca's at the unit and see if the noise is still present.

dedlyjedly · Post by **dedlyjedly** » Sat Sep 11, 2010 4:15 pm

It COULD be a lot of different things. In fact there's a chance there might be multiple problems causing noise in your system. Due to these possibilities it is very important to systematically approach this task instead of randomly trying "this" and swapping out "that."

Errin created a nice cheat sheet for PG dealers and was kind enough to share it with all of us. Review it once thoroughly and then give his approach a shot. It is important to follow ALL the steps and in the right order to insure the integrity of the testing!

http://phoenixphorum.com/trouble-shooti ... vt178.html

It may seem like a lot of trouble and effort, but its a hell of a lot better than losing your mind because you THINK you've tried everything!

Post by **ttocs** » Sat Sep 11, 2010 6:44 pm

as a last resort I would run a power and a ground wire from the deck back to the amp. Hook those wires up to the amps power/ground and then use those wires to power the deck so they are all getting power and ground from the same location.

dwnrodeo · Post by **dwnrodeo** » Mon Sep 13, 2010 2:57 am

Thanks for the help guys. I took a break from it yesterday as I didn't need the stress. I think I might have a problem with my speaker wire exposed somewhere. With all of the RCA's unplugged from my headunit and amps, I am getting a static noise from the left side only when the key is turned on just before starting. I'll take a closer look at it when I get a chance and report back.

dwnrodeo · Post by **dwnrodeo** » Tue Sep 14, 2010 2:27 pm

O.K. I'm back at it now and something is fucky. In fact, it has me scratching my head in bewilderment. I disconnected my tweeter, ran a separate speaker wire directly from the amp to the tweeter outside of the vehicle. I ran a set of RCA's from the headunit directly to the amp. All other amps are disconnected. I ran a jumper wire from the amp positive power terminal to the remote terminal to keep the amp on even when the vehicle is off. The key is NOT in the ignition. The only thing on is the dome light, no other accessories. I still have fucking static! I unplug the RCA's from the headunit and it gets worse! I turn on my garage florescent lights, it gets worse! I use a different speaker in place of the one connected tweeter. Still noise. I tried a different amp. Still noise. I unplugged the battery terminal from the battery and ran a battery charger to it. Still has noise! Can somebody help me?!?

Post by **ttocs** » Tue Sep 14, 2010 2:39 pm

try a different source? Try a mp3 player with a headphone to rca cable and see if its still there.

Ahsmo · Post by **Ahsmo** » Tue Sep 14, 2010 3:33 pm

you have discovered why I cannot stand aftermarket full blown stereos

You have done everything I can think of.

What kind of car do you have? Does it have anything that produces really high voltages? HID lights?

Post by **ttocs** » Tue Sep 14, 2010 3:46 pm

is the chassis of the amp grounded?

dwnrodeo · Post by **dwnrodeo** » Tue Sep 14, 2010 3:51 pm

Static is still there with mp3 player. I just tried an mp3 player with a different amp, with a separate battery, connected directly to the tweeter all outside of the vehicle. I tried a different speaker and I still hear static. Maybe I'm just being too anal about it, but it is quite audible.

dwnrodeo · Post by **dwnrodeo** » Tue Sep 14, 2010 3:55 pm

Ahsmo wrote:you have discovered why I cannot stand aftermarket full blown stereos

You have done everything I can think of.

What kind of car do you have? Does it have anything that produces really high voltages? HID lights?

I might be beginning to feel the same way. The vehicle is a 2003 Ford Explorer. Other than the stereo, it is bone stock. The sad thing is, before this happened, it was by far the nicest car stereo I've ever heard.

Now I just want to rip everything out and go back to having mediocre sound with less headaches.

dwnrodeo · Post by **dwnrodeo** » Tue Sep 14, 2010 3:56 pm

ttocs wrote:is the chassis of the amp grounded?

Nope. It is mounted to 3/4" MDF, which is mounted over top of Second Skin Luxury Liner which is a 3/8" thick layer of foam. Thanks for all your help though.

Thunderdome · Post by **Thunderdome** » Tue Sep 14, 2010 5:17 pm

has anyone else heard this noise or is it just you that hears it

sorry had to throw in a little humour, I think I would be loosing it myself by now somebody must have an idea

dedlyjedly · Post by **dedlyjedly** » Tue Sep 14, 2010 5:53 pm

dedlyjedly wrote:It COULD be a lot of different things. In fact there's a chance there might be multiple problems causing noise in your system. Due to these possibilities it is very important to systematically approach this task instead of randomly trying "this" and swapping out "that."

Errin created a nice cheat sheet for PG dealers and was kind enough to share it with all of us. Review it once thoroughly and then give his approach a shot. It is important to follow ALL the steps and in the right order to insure the integrity of the testing!

http://phoenixphorum.com/trouble-shooti ... vt178.html

It may seem like a lot of trouble and effort, but its a hell of a lot better than losing your mind because you THINK you've tried everything!

Did you follow the steps in the link? Brian even has the download posted to you can print off a copy to take with you into the "field!" If you follow the process you will narrow down the possibilities. If you do any of these individual tests in a random order they can lose their validity and you could mistakenly rule out the culprit. Follow the steps and let us know if you have any questions or where you run into a problem.

dwnrodeo · Post by **dwnrodeo** » Wed Sep 15, 2010 2:51 am

dedlyjedly wrote:
dedlyjedly wrote:It COULD be a lot of different things. In fact there's a chance there might be multiple problems causing noise in your system. Due to these possibilities it is very important to systematically approach this task instead of randomly trying "this" and swapping out "that."

Errin created a nice cheat sheet for PG dealers and was kind enough to share it with all of us. Review it once thoroughly and then give his approach a shot. It is important to follow ALL the steps and in the right order to insure the integrity of the testing!

http://phoenixphorum.com/trouble-shooti ... vt178.html

It may seem like a lot of trouble and effort, but its a hell of a lot better than losing your mind because you THINK you've tried everything!
Did you follow the steps in the link? Brian even has the download posted to you can print off a copy to take with you into the "field!" If you follow the process you will narrow down the possibilities. If you do any of these individual tests in a random order they can lose their validity and you could mistakenly rule out the culprit. Follow the steps and let us know if you have any questions or where you run into a problem.

I have done most of these already, but not exactly in that order. I am off work Friday so I will re-connect everything and follow these steps exactly. Thanks.

Quick question for you guys. How do I go about checking the continuity of my RCA's?

has anyone else heard this noise or is it just you that hears it sorry had to throw in a little humour, I think I would be loosing it myself by now somebody must have an idea

I'm not the only one. I had my brother verify to make sure I'm not losing it. I even demonstrated how the fluorescent lights made the static hum louder when turned on and he agreed.

dedlyjedly · Post by **dedlyjedly** » Wed Sep 15, 2010 9:18 pm

You can effectively test for continuity on your RCA's by testing the resistance from one end to the other using a dmm. You'll do the test three time for each rca though (that means 6 tests per stereo set!). Once on the center conductor and once on the outer shield, and finally a test to make sure there is no continuity across the center and outer conductors. You can use the audible setting if your dmm has it, but I recommend actually checking the digital readout for the resistance. This is because high resistance on the circuit can cause issues even though it may pass the audible test. You'll be looking for a resistance fairly similar to the reading you get when you hold the two probes together. When you test to make sure center and outer conductors aren't shorted nothing should register on the readout.

dwnrodeo · Post by **dwnrodeo** » Wed Nov 10, 2010 4:53 am

A little update: Yes, I have been working on this since September and it is still not resolved.

This past weekend I went to Autozone to have the battery and alternator checked and the battery was good, but the alt came back as having failed diodes. Cool I thought, problem solved. I replaced the alternator, fired it up and the alt whine coming through the speakers was reduced but still apparent.

I have gone through the PG Tech Tips for trouble shooting alt noise. My symptoms are: Pops and clicks when different things are turned on (lights, ignition, etc...) high noise floor when vehicle isn't running, and alternator whine when the vehicle is running. I also have noise when the the CD player changes tracks between songs. According to the Tech Tips it states:

Power Noise: Power noise is the most common problem and is typically related to problems with the starting and charging systems of the vehicle.
* Common symptoms: whining sound that changes when you move the gas pedal (yes), nosie when you first start the vehicle that gradually goes away after running for a while (no), pops and clicks when you operate other vehicle systems (yes).
* Causes: weak battery (checked O.K.), bad alternator (replaced), bad starter (?), bad ground (all 0 gauge from alt to battery to amps, same ground point for ALL components in system), corroded battery terminals (no)
*Quick Checks: check battery voltage, should be 12.3-12.6 volts with the vehicle off (12.1-12.3) and 14.4-14.7 volts with the vehicle running (14.46)

It varies in severity. One moment it's unbearable, the other it is tolerable. If I keep the gains down on my crossover/line driver and turn the music up, it is bearable. Turning the gains up on the line driver exacerbates the problem. By using the PG Tech Tips, I have deduced that the amplifiers are fine. When I unplug the RCA's from the amp there is no noise. When I reconnect them, then disconnect the RCA's from the head unit there is still noise. I checked the RCA's for continuity and they are fine. I've plugged in another set of RCA's and ran them from the headunit to the amp outside of the vehicle and have noise. When I use my iPod as a signal source plugged directly into my crossover, the alternator whine is gone and my noise floor is lowered, but the pops and clicks are still present when my vehicle dome light comes on or off. I'm guessing that my head unit may be faulty, but I really don't want to drop another $300 until I'm fairly positive that this is the problem. Any ideas on other sources of a ground loop?

I've gone through each driver and checked the voice coil resistance, checked the speaker wires for continuity and to see if any voltage is coming through indicating a bad wire, checked continuity of power cables, made sure the amps are not grounding to the frame, and a list of other things that could be wrong. I just want to throw this info out here to get opinions before I purchase another head unit and find out it is something else.

Post by **ttocs** » Wed Nov 10, 2010 4:59 am

you have tried grounding the outer shiel already right? ]
Have you tried both cleaning and retightening the grounds, and trying to powerthe deck at the same point as the amp/eq? try running two wires to the amp/eq poiwer point for power/ground and see what happens.

We might have gone over this before but I really do not want to read all of it again.

Post by **ttocs** » Wed Nov 10, 2010 5:03 am

dwnrodeo wrote:O.K. I'm back at it now and something is fucky. In fact, it has me scratching my head in bewilderment. I disconnected my tweeter, ran a separate speaker wire directly from the amp to the tweeter outside of the vehicle. I ran a set of RCA's from the headunit directly to the amp. All other amps are disconnected. I ran a jumper wire from the amp positive power terminal to the remote terminal to keep the amp on even when the vehicle is off. The key is NOT in the ignition. The only thing on is the dome light, no other accessories. I still have fucking static! I unplug the RCA's from the headunit and it gets worse! I turn on my garage florescent lights, it gets worse! I use a different speaker in place of the one connected tweeter. Still noise. I tried a different amp. Still noise. I unplugged the battery terminal from the battery and ran a battery charger to it. Still has noise! Can somebody help me?!?

ok I lied I was reading anyway.

REading this one makes me wonder if the outputs on the deck are not corroded or sometihng. You should not have statice connectiong/disconnecting the rcas. Some popping, maybe a thump but not static. Try to tug/pull/manipulate the rcas on the back of the deck and see if it does it. Try some light tapping on the deck to see if the static comes/goes.