I seem to be getting a hum on the chime speaker when the headunit is on. It is constant, and never stops until the deck is turned off.
I am using a Kenwood DNX5120 and a GMOS-1 adapter. I have it wired in properly, everything works great, except for this annoying buzz/hum.

I am using the power/ground source from the OEM harness. Would I be better off to tap a ground somewhere else? Possibly on a bolt behind the dash? Would this help?

I have the chime speaker setup as my dash speaker since I am using aftermarket speakers/stereo, and I had the Monsoon setup when I got the car. This way here the deck is hooked up to the amps, not using any of the OEM harness. I took the GMOS-1 front left speaker outputs and tied them into the dash speaker so it was actually used for something (door chimes and OnStar if I ever used it).

I took it apart again yesterday to make sure nothing was rubbing/exposed, even wiggled everything to try and alter the sound, but nothing.

I am starting to wonder if the adapter is just a piece of junk that hums when it gets power... I remember how annoying it was when I use to tie it into the OEM harness. Your music from the front left speaker would always cut in/out and never be as loud as the rest of the speakers output. Glitchy.

_________________
T66 Turbo,3" downpipes, oversized A2A,Stg3 heads/cam,hv3,built trans,bilstein struts,ssc springs,gxp brakes,pace car spoiler(1of3??),lots more.. dyno'd @ 421WHP~13lbs boost on OLD setup. New = ???

I got the same problem but with the GMOS-04, and am thinking its just a crappy ground. I started swapping out my grounds, and actually ran an 8 gauge ground cable out to the chassis ground, then to a distribution block behind my deck to plug in the deck and steering wheel control box(overkill i know) but ran out of time to finish hooking it up so i dont know if it will get rid of the hum. I am running my setup directly to amps then to aftermarket speakers as well, and the problem is only happens when the deck is on too. Does your noise speed up as you hit the gas like alternator whine too?

_________________

Normally a bad ground, trying running both the radio ground and adapter ground straight to the frame. There are a couple spots on both the driver and passenger side kick panels. It that doesn't work there is possibly a ground loop in the electrical system, Normally this is found right at the battery and the main ground is bad.

-- Wed Sep 22, 2010 1:46 am --



The ground should be no more then 18 in ( amps, radio, EQs, etc ), this insures less interference, and less chance of ground loop - ( normally cause for the noise )

_________________
2004 Grand Prix GT AGGRESSOR
PRJ PCM, Custom Exhaust, 180 stat, FWI Custom Intake, DIC upgrade.

So, I finally started to play with this, turns out it's not the adapter that's humming. It was deceiving because the sound seemed centralized in the dash, aka, center speaker, but it's coming from all speakers.

When the amps power on, the hum emits. I thought it was the RCA cables being routed near something causing EMI, but, I disconnected those and ran a set directly over the seats to the deck, and it did the same thing, so I eliminated it.

I also disconnected my set of RCA cables bouncing the signal to the sub amp, nothing changes.

I had a bit of slack left on the primary ground cable at the rear of the car, I removed another 6 inches of wire, nothing changed.

I can't seem to isolate the reason this is happening, anyone have any other ideas? I tried grounding the deck inside the dash instead of using the car's OEM harness, but it caused a horrible sound making things worse.

No idea what the problem is...

_________________
T66 Turbo,3" downpipes, oversized A2A,Stg3 heads/cam,hv3,built trans,bilstein struts,ssc springs,gxp brakes,pace car spoiler(1of3??),lots more.. dyno'd @ 421WHP~13lbs boost on OLD setup. New = ???

Well, i grounded my adapter, stereo, and steering wheel control harness straight to where the main ground is off the strut tower with some 8 gauge cable, and it seemed to eliminate some of the sound, but it is still there... I also tried disconnecting the center speaker, and nothing changed, so i have no clue what it could be now.... Oh well, all you have to do is crank the music up to drown out the whine...

_________________

This makes me wonder a little cause the GMOS-1 is prone to issues such as this. Is that speaker also being used with the system or only for onstar and chime? Its possible having the GMOS-1 connected this way could be causing the interference you are experiencing have to love troubleshooting.

Could you possibly describe your system layout including connections?

-- Sun Oct 03, 2010 5:51 pm --




Have you replaced your ground for your alt? If you are getting whine that accelerates when you hit the gas that is normally the alt. Replacing the ground on the alt could fix that since interference is still occurring while connected to the main ground.

_________________
2004 Grand Prix GT AGGRESSOR
PRJ PCM, Custom Exhaust, 180 stat, FWI Custom Intake, DIC upgrade.

GMOS is being used for OnStar and chime only. No harness speaker wires are connected to the deck.. RCA plugs go to the back of the car on the driver's side.. Amp turn on and power run on the passenger side.

Front speaker wires are run on each side of the car..

Deck has RCA plugs for front/rear channels, navigation antenna, regular antenna, ipod input (USB + mini headphone jack) and steering wheel control interface.

4 gauge power wire through a fuse at the fusebox up front, to the rear fold down seats.. 1 x 450W amp and 1x 600W amp.
Power goes to a split, 8 gauge wire to each amp.. Ground is in the trunk approx 24 inches away to allow slack to fold down the seat. Same size wire split the same as power. Amp turn on wire is split to each amp...

RCA inputs from deck go into 4 channel speaker amp, then the "output" connection is hooked up to the input on the subwoofer amp.

16 gauge wire is run from the amp to all the speakers throughout the car...

I am starting to wonder if the fan in the Kenwood DNX5120 is the culprit of the hum.

_________________
T66 Turbo,3" downpipes, oversized A2A,Stg3 heads/cam,hv3,built trans,bilstein struts,ssc springs,gxp brakes,pace car spoiler(1of3??),lots more.. dyno'd @ 421WHP~13lbs boost on OLD setup. New = ???

Yes, I have 1/0 grounds for the main grounds, so grounding shouldn't be an issue... Right now i have just my front 6.5's on an aftermarket amp, and some front tweeters off the deck, so once i get some new 6x9s for the back and amp them and completely unplug the factory amp my noise issue will probably go away... I guess I will find out whenever i can find the right set... Most likely the noise is just coming from the crappy adapter, i hear the gmos 04 has quite a few problems with things like that...

_________________

I was just about to ask if your head unit had a fan lol, this happened to a couple kenwood decks I have worked on. From the schematics for the that model the fan does run off the sound processor power. Now there is also a filter shown but that is possible to fail.

Now there is a way to test this - Gather some small speaker wire and ground the RCAs ( you do this by using the small speaker wire and wrapping it around each L and R RCA plug and then ground it to the frame of the unit -- NOTE: When you wrap the wire use the RCA plugs to assist on holding the wire on the female RCA connector so its easier). If the noise is gone then its possible the fan is causing the issue or the filter on the sound processor is failing.

-- Sun Oct 03, 2010 11:40 pm --




If the factory amp is still in the picture that could be your issue, and yes the GMOS 04 is known for short comings, I hated filing the warranty claims.

As for 6x9s I purchased the Pioneer REV series because of the tweeter material design and cone design and structure. To my surprise the freq response of 28hz to 30,000 hz is unreal and clarity is amazing. Now take into mind I am running that on a sundown 100.4 so using a amp to power them and to adjust them provided a benefit

_________________
2004 Grand Prix GT AGGRESSOR
PRJ PCM, Custom Exhaust, 180 stat, FWI Custom Intake, DIC upgrade.

I was reading about grounding the RCA cables as another option... I figured something was wrong, because when everything is powered on, if I touch an RCA plug with my finger, I can hear the pitch of the hum change...

Does it matter if I wrap some wire around the RCA connections at the amp and just ground to frame? There isn't much room left behind the dash after all these modules are squeezed in. If it needs to be on that end, I'll make it work, but it's easier the other way of course.

Thanks for the feedback, much appreciated.

_________________
T66 Turbo,3" downpipes, oversized A2A,Stg3 heads/cam,hv3,built trans,bilstein struts,ssc springs,gxp brakes,pace car spoiler(1of3??),lots more.. dyno'd @ 421WHP~13lbs boost on OLD setup. New = ???

Try the amp first and see the results, if that doesn't work do the radio. If you use small wire and wrap it around each female RCA connector twice then plug the RCA cables in there wont be much bulk at all and should slide right in.

_________________
2004 Grand Prix GT AGGRESSOR
PRJ PCM, Custom Exhaust, 180 stat, FWI Custom Intake, DIC upgrade.

I understand the female part is the outside of the cable, but they have plastic shielding and what not. How do I affix the wire properly? Also, if I wrap around one two times, then daisy chain to the next, etc, and then ground that single, is that fine? Or are we talking an individual ground wire for each RCA terminal?

Thanks again..

_________________
T66 Turbo,3" downpipes, oversized A2A,Stg3 heads/cam,hv3,built trans,bilstein struts,ssc springs,gxp brakes,pace car spoiler(1of3??),lots more.. dyno'd @ 421WHP~13lbs boost on OLD setup. New = ???

Chain linking is fine and is recommended to assist with ground loop elimination. The Female RCA connector is the connector the RCA cable will connect into on the radio and the Connectors on the RCA cable are called Male. What you are going to wrap are the RCA connectors on the radio - If you want to make it easy- use 24 gauge wire that is solid and not twisted ( you can find it at walmart, radioshack, any autoparts store. Using the solid wire retains shape easier and chaining is easy.

I may have a old radio with RCAs - I will check tomorrow and will take a couple pics of the wire rapped around the RCAs to give a better idea.

_________________
2004 Grand Prix GT AGGRESSOR
PRJ PCM, Custom Exhaust, 180 stat, FWI Custom Intake, DIC upgrade.

Damnir - What kind of deck do you have? (Sorry if you said what you have before, I only read the last 3 posts or so)

-- Thu Oct 07, 2010 12:47 am --

* F*ck, I read the 1st post. I see you have a Kenwood.. I know Pioneers are notorious for humming, where you have to ground the female RCA plugs on the back of the unit.. but I've never heard of that coming from a Kenwood?

_________________

i would put money on the adapter being your culprit although it does seem weird that would be the issue considering your setup but i had the same issue with almost the same exact setup i had a stock monsoon 6 disc in dash and upgraded to a kenwood dnx6140 with gmos and i had a constant hum played with it a bit and said screw it and bought a pac adapter with onstar retention and not a problem since granted i was sticking with everything else stock (speakers and amp) but just food for thought those gmos adapters are garbage in my opinion i cant believe they still sell them

What did you pay for that PAC one? and where?

I'm going to try the RCA ground technique this weekend when I have some time. I'll keep the other part/suggestion in mind depending on how far I want to go with this. Hah

_________________
T66 Turbo,3" downpipes, oversized A2A,Stg3 heads/cam,hv3,built trans,bilstein struts,ssc springs,gxp brakes,pace car spoiler(1of3??),lots more.. dyno'd @ 421WHP~13lbs boost on OLD setup. New = ???

umm i wanna say i payed like 100 for it and then an extra like 60 for the steering wheel controls adapter which is optional if you want to retain support for that i dont exactly remember the site but i just googled the model number and went with the cheapest site pac-audio.com and you can search there the os-2c will retain your onstar but not a factory amp and the os-2c-bose will retain your factory monsoon which is what i got its not cheap but its well worth the cost i have had mine about 2 years now and its worked great if i remember correctly there is a 3rd adapter to retain chimes and audible alerts someone correct me if im wrong anyway good luck hope ya get it working

Right now I have chimes, Onstar retention and the steering wheel control interface. Just wanted to keep this in mind if I can't resolve the hum this year.. Will make this a winter part order and tackle it in the spring.

_________________
T66 Turbo,3" downpipes, oversized A2A,Stg3 heads/cam,hv3,built trans,bilstein struts,ssc springs,gxp brakes,pace car spoiler(1of3??),lots more.. dyno'd @ 421WHP~13lbs boost on OLD setup. New = ???

Yep the sound board on the kenwood, pioneer and including the lower model alpines are all purchased from the same parts manufacture. The pioneers are notorious but normally due to the improper ground to the radio chassis. Thats what adding a ground to the RCAs works perfect lol.

-- Sat Oct 09, 2010 9:22 am --




I wish you had a oscilloscope, finding this hum and interference would then be cake lol. Just tossing a idea out there have you attempted adding a power filter to the wires for the GM0S 1 and steering wheel interface? I did this for a 2005 gp a while back and it helped tremendously.

_________________
2004 Grand Prix GT AGGRESSOR
PRJ PCM, Custom Exhaust, 180 stat, FWI Custom Intake, DIC upgrade.

I don't know if this is causing your humming noise or not, but I've always connected the power wire directly to the battery with an inline fuse.

_________________
07 Black GT- Wizair, GMPP sway bars, STBs, T/As, Pioneer-Alpine-PolkAudio
RIP: 97 Black GT 212,832miles, GMPP suspension-sway bars-STBs-T/As, K&N, 180stat, ZZP DP-GMPP exhaust, Alpine-Orion-Polk Audio

First off, what is this "power filter"? Second, I have my power cable for the stereo off of the side of the fuse box where the power cable comes from the battery. I don't understand how going directly to the battery (12 inches away) which is connected to the main cable is going to alleviate anything, since it's more or less one big cable from A to B.

_________________
T66 Turbo,3" downpipes, oversized A2A,Stg3 heads/cam,hv3,built trans,bilstein struts,ssc springs,gxp brakes,pace car spoiler(1of3??),lots more.. dyno'd @ 421WHP~13lbs boost on OLD setup. New = ???

The power filter or also known as Power wire Isolator and Noise Isolator, is a Electronic filter helps to lower resistance to keep the power flow clean - this has been known to help eliminate hum but is kind of a band-ad.

Power filter

As for the cable, Allowing a direct connection without any type of bridge or secondary connection will allow the lowest resistance possible. This would also eliminate outside interference that a different connection my be producing.

Size of wire can also be a factor - Stereos 14 to 16 gauge is recommended but 18-22ga is the most common.

Smaller cable = more resistance = restriction of power flow = Electronic interference ( hum noise )

Larger cable = less resistance = greater power flow = Low or no Electronic interference ( hum noise )

_________________
2004 Grand Prix GT AGGRESSOR
PRJ PCM, Custom Exhaust, 180 stat, FWI Custom Intake, DIC upgrade.

I tried grounding the female portions of the RCA cables at the amp, makes the hum 10x worse. So, for now, not sure what else to do. I tried to wrapping electrical tape around all the plugs to avoid anything from touching, also did nothing.

I'm sure there's something I'm overlooking....

_________________
T66 Turbo,3" downpipes, oversized A2A,Stg3 heads/cam,hv3,built trans,bilstein struts,ssc springs,gxp brakes,pace car spoiler(1of3??),lots more.. dyno'd @ 421WHP~13lbs boost on OLD setup. New = ???

Yep, you stated it made it ten times worse, that means the interference is not the RCA's but possibly the GMOS-01 adapter, head unit, or amp.

I know this will sound dumb but its the easiest troubleshooting setups I can think of:

Amp test:
If you have a phone that has a head phone jack or MP3 player Use a L/R RCA Jack to 3.5mm mono headphone jack cable ( get these at walmart for $5 ) and connect that to your amp, see if the same interference occurs with the head unit completely out of the equation.

Head unit test:
Next Remove the GMOS-1 Adapter and connect the Radio Red ( 12v), Yellow ( 12 volt constant ), Black (ground) wire directly to the battery, Dont run the cable through the car use speaker wire and connect both the Positive and ground on the battery and just let it sit on the outside of the car and run it thought the window. The radio will stay on and then you can test to see if the radio is causing the interference without any possible connection causing a issue.

_________________
2004 Grand Prix GT AGGRESSOR
PRJ PCM, Custom Exhaust, 180 stat, FWI Custom Intake, DIC upgrade.

First thing you need to do is figure out if the issue is UP stream or DOWN stream.

Unplug your RCA's from the amps and throw an iPod in there. Tell us if it hums still. If it does...problem is down stream. If it doesn't, problem is with your Head Unit and associated wiring.

_________________

11 is louder than 10!!...innit?
Audio Build Logs: DIYMA and GPONA