PistonHead

I am having a rather large problem with noise in my system. I have searched the forum and tried as many of the ideas as I could.

Sorry for the following long post, but I hope as much info as I can provide might help.

Initially after the original install, I had no noise. I had the system in for about a week and while I was switching CD's, I noticed a noise start. I thought the noise was an unbalanced CD or something. Ejected it, re-insert, try another CD and that's when I realize that it is a whine/ ticking in the system. I had to let it slide for a couple of days before I could get to it. All the while the noise was actually getting worse.

System in a 2001 GMC Sonoma

Pioneer DEX-P9
Kicker KX 700.5
Premier component set
JL coaxial set
4 gauge power and ground

Now on to what I have tried so far and the results.

Re-did my ground. It is right to the frame. (ground frame clean)
head unit is now grounded to the frame, right next to the amp ground. (ground clean also)
Tried different RCA's (no difference)
Moved wires, RCA's you name it. (no difference)
Added 4 gauge grounds from the battery to the cab, and frame. (no difference)

Wired the headunit directly to the amp, short RCA's using the amps + and - terminals for the deck. No noise. I thought I had made some progress, but read on.... I reinstalled the deck in the dash...

It turns out, if I keep my antennae unplugged, I don't have any noise. As soon as it plugs in, I get all kinds of ticking and alternator whine.

If I take the ground wire for the head unit(from the frame), and ground the metal in the dash, as well as the deck, I get lots of noise. Antennae in or out it doesn't matter. As soon as I remove the dash ground then it goes back to having noise only when the antennae is plugged in.

Obviously I have some kind of issue with the dash ground and or the antennae gound. I thought that would be eliminated by using the cabs ground and running 4 gauge directly to the negative terminal. My power wire is run close to the antennae, but I have never heard of noise being introduced through the antennae.(?)

Anyone have any ideas. I have tried as many things as I could find in other posts.

Sorry for the long post.
Thanks for any help.

Presently in a low noise environment without any radio reception. [img]smile.gif[/img]

Later,
Brad

edgar

back when I was running a Denford 8250 I was having the same problem, except it would do that regardless of what I tried to do. Never could track it down, my assumption is that it was simply a faulty deck. Only thing I know is that the noise whent away when swapped to a different deck, in three different cars...

maybe try switching out the deck to something else and see if the noise persists?

[ January 17, 2005, 07:15 AM: Message edited by: edgar ]

JohnVroom

I have had evil grounds before and bought an antenna isolator (installs in series with the antenna wire). They are available on-line but I bought mine at a local shop. I could send you mine... shipping would be a killer

http://www.installer.com/acc/ about half way down the link

[ January 17, 2005, 07:53 AM: Message edited by: JohnVroom ]

Haunz

iTrader: (3)

neg on the antenna is same as ground... where did you have power comming from when the antenna was unplugged and you had no noise ???


You have ground loop that is caused by AC noise from your alternator being induced on what your deck consideres reference ground...

Try running the HU from an external power source (spare battery or 12v power supply) if the noise goes away then your HU is the problem...

try a choke on deck ground, buy a DC/DC powersupply, get a line driver to lower noise floor, or buy a deck with an isolated powersupply....

Edit: I would not recommend using a choke on the signal... (ie. passive ground loop 'isolaters' that you plug RCAs into)

[ January 17, 2005, 10:46 AM: Message edited by: Haunz ]

theboy

i HAD THE SAME PROBLEM AND IT WAS MY REAR PREOUT RCA'S TOUCHING GROUNG. MABEY??????

Haunz

iTrader: (3)

^yea, that could do it... I think hes had it running out of dash already though... ?

PistonHead

That antennae isolator looks like it might work.

I'm trying every last possible thing before I swap headunits to see what happens.

Thanks guys,
Brad

PistonHead

Haunz,

I have hooked the deck up directly from the power and ground terminals on the amplifier (with the deck on floor behind the seat) and had no noise. But, I was not able to plug the antenna in while hooked up like that.

I have had the deck running on the seat, without anything grounding the RCA's. This made no difference in noise. Plug in the antenna and noise returns. Connect a ground from the dash support to the chassis and the noise returns. I ran a ground wire from the - terminal on the amp to the outside metal of the antenna and it reduces the noise some. It is still very noticable like that though.

Out of everything I did, the only thing that made a difference was isolating the deck from the dash ground and unplugging the antenna.

It is now installed in the dash, with the ground going to the same spot on the frame that the amplifier is grounded. This now completely isolates the deck from ground in the dash, until you plug in the antenna.

There is no noise (or very, very little) when hooked up like this. If you ground the chassis to the dash supports or plug in the antenna, the noise returns.

So, if I hook up a spare battery to run the deck, and there is no noise, does this mean the deck is the problem?

Thanks for the help.
Brad

JohnVroom

An important point you made... The noise slowly came into prominence! What, if anything, has changed in your system or with the car (weather, car wash, rust, road salt, etc.). A single component in a power supply could have gone slowly failed

My ground or ground like noises have come from many things:
1 As stated: bad ground points, RCA's OR speaker wire touching ground, noisy car (some VW and my SHO were horrible), if the car is aging there could be an issue almost anywhere

2. Not stated: I had a very noise sensitive Audio Control EQX, a very noise sensitive ADS crossover, a poor solder point in an RCA introduced noise even though it was not grounded (this could be a problem in the deck BTW). My SHO is old and some of the seals had weakened over time, so when it rained I got alternator whine (maddening, especially when you take your car to a car wash before a competition). Given I had 2 or more of these at the same time… troubleshooting was very hard. The antenna isolator didn’t solve anything for me (but it had for a friend of mine).

The in line RCA line isolator you have been warned against will stop the noise BUT it is not recommended for some amplifiers (US Amps). The unit will reduce SQ and add to your noise floor (I used an uber expensive Jensen noise filter too).

The DC power supply filter or DC/DC power supply might be a good idea BTW (most of Haunz suggestions are good BTW).

CARSOUND has good troubleshooting tips BTW and surprise surprise David Navone sells a lot of what he recommends using!

Haunz

iTrader: (3)

If you have no noise untill the antenna is plugged in it, makes sence that an isolator for the antenna would work....

first Id try taping the outer part of the plug so it makes no contact when you plug it in... this should still allow your HU to pick up radio signals.....