Gooday All,
As some would know,
a while ago I had a bit of trouble with my Amp/stereo setup,
it had a "whine" (with the ignition ON- BUT not when switched to ACC),
I assumed it was the amp & tried running it from a different power supply
(another car ) =NO change, whine still there,
so after many days screwing around and many $$$
for filters of every kind (whine still there) I gave up and went back
to just using the headunit (NO WHINE).
Since then I've got a new headunit, so I figured
I'd hook my Amp back up while installing the H/Unit.
All went well 'til I switch the ignition on and
there was the whine again....BUGGAR !!!!
I'm convinced the Amp is picking up interference from something,
just cant work out what. Cant be the Dizzy as it's not connected up.
So I'm stumped at what could cause this.
Any Ideas/suggestions Welcome
(yes, I've thought of tossing the amp but it was a gift from the wife).
Oh well, back to the workshop.

Gav

 

Update,
Well, after some "liquid inspiration", I thought I'd try something.
I completely disconnected the alternator wiring and low and behold
the whine is almost gone.
It's still there but alot less than before
(and that maybe just be the headunit itself).
Now to find out.... Why the alt would make it louder ???
Cheers,
Gav

 

The alternator has brushes running on a commutator. That generates 'pulsed' current, thus current spikes. GM's answer for that problem was to put a simple capacitor in the circuit that dampened the spikes. I don't know the capacitor specs, but Radio Shack should have a noise suppressor condenser/capacitor that you could connect to the alternator as shown in the AIM.

 

I'll give it a go.
Thanks.

 

Where do you have the head unit grounded to? If you have it grounded through the factory radio harness wire, change it to a metal portion of the car that is common to ground, and make the wire as short as possible. The same goes for the amp - where do you have the amp grounded? If it is connected directly to the battery's negative post, then you are asking for electrical noise! Same as the head unit, ground it to a metal part of the car that is common to ground, and make the wire as short as possible. Also make sure the amp is not grounded through the amp's chassis, only grounded through the ground wire connection.

If changing the grounds doesn't work, install noise filters on both the constant 12v and the switched 12v supply wires to the head unit. I used one filter with a relay to run the swtiched 12v through the same filter to only have one filter behind the radio, but either way will work.

If that doesn't work, next step is the signal path. What kind of signal wires are you using between head unit and amp? Cheap cables with poor shielding are also asking for electrical noise. The best I've found for noise rejection so far these days are the newest type that use UTP (unshielded twisted pair) technology, which is the same as modern network cables CAT5, CAT5e, or CAT6. An added bonus to this type of cable construction is that it is much smaller in diameter than traditional shielded RCA cable, making it easier to route through small spaces. I used a 4 channel UTP cable that was about 5/16" in diameter! I used this exact cable:



http://www.ebay.ca/itm/Tsunami-V104-...item519bebc744

Some or all of the above solutions should end your problems.

*One more thing I will mention is the amp itself. Poorly made (cheap) amps and also older amps (20+yrs) are also tend to have problems with noise.*

 

Try grounding it to the frame only. It could be the amp!!! I had one do some strange things right before it burned up. Good luck

 

I installed an MSD noise suppressor 10 yrs ago and have had no issues since.

 

Thanks guys,
I'll give your suggestions a go.
Got another amp, so I'll be able to see if it has the same prob.
I also got a great deal on some noise suppressors
(condenser/capacitor) 5 for $4.
http://www.ebay.com.au/itm/5-X-CAR-R...item5d31c97242
Now for a really DUMB question....
How are they wired in ?????

Thanks again for the advice,
I'll keep ya posted on my progress.
(Too bloody hot to do anything tonite).
CHEERS,
Gav

 

In my 73, I wired the noise suppressor to the positive output and the ground nut on the case.

 

I used to have that problem I just connected the amp directly to the battery... both + and - ... I have the Original H.unit so I didn't change the harness. I only took the power antenna + to give the power on signal to the amp.

But In my SUV had that problem and did almost the same thing took 2 cables directly from the battery to the head unit and the amp... also used a good shielded RCA for the sound signal. and a noise suppressor that was for the RCA, and you plug the RCA from the head unit to the suppressor and it the suppressor to the amp...

 

1. make sure the ground on the amp is a good ground point on the chassis, preferably direct to the frame and as mentioned try to keep the ground wire as short as possible.
Also make sure the ground wire is AT LEAST the same gauge as the power wire.
BTW, since it's a C3 car and the battery is already in the back you can very easily try a ground direct to the battery which contrary to what has been posted is actually your best bet. Second best bet is to run the ground to the same spot on the frame that the battery is grounded to but that means a longer ground wire run thru the body to the underside and grounding on the frame same as the battery.

2. keep all signal wires (the RCA lead wires from the radio headunit to the amp) as far away from other wiring, especially power wires as possible. It's common to run all the wiring (power, ground, signal) from the radio back to the amp all together because it's easy for the install but it's bad for noise issues. I always run power on one side of the car, gound on the other side, and signal cables down the middle, keeping everything seperate.


If either of these two suggestions don't help than it's time to start fooling with noise suppresor filters but honestly those are always a last ditch effort and a bandaid at best. It's always better if you can foind the source of the noise and fix it rather than "hiding it" with filters.


I used to be in the high-end car audio business and have designed and helped install some of the top competetion car audio systems out there and we VERY, VERY rarely ever had to deal with noise issues regardless of the size of the systems we put in because of careful thought process on ALL the grounds throughout the system and careful routing of all the system wiring, especially keeping signal wires away from all power type wires.

BTW, is the alternator the stock unit or an aftermarket "hi-output" alternator. Stock alternators aren't usually a big problem but aftermarket units can drive you batty trying to deal with noise issues.

Good luck

 

i put a wire from the alternator to the frame .fixed my noise.

 

In addition to what Barry has posted, here is a link you can use to help diagnose the problem:

http://www.termpro.com/asp/pubs.asp?ID=121

DC

 

Greetings All,
Just a qwik update.
Well, I discovered today that if I ground the amp/headunit
to the seatbelt bolt the whine is dramatically reduced.
(Amp was connected directly to Batt. but H/U was only grounded to it).
So I'm making progress, I'll get back onto it tomorrow
as it's OUR 23rd WEDDING Anniversary today.
So I'd better spend some quality time with the "OTHER" woman for a change....
Have a Great Weekend,

Gav

 

IT's fixed !!!!! Thanx to everyone's help.
You GUYS ROCK !!!
I found the problem. The Headunit earth
was "dodgy" so I ran a larger wire to a bolt under the dash
and "HEY PRESTO", Noise gone.
I found the gauge cluster ground was dodgy too, so it's been replaced and relocated too.
So to sum up......
Check your Grounds/Earths.... FIRST !!!!
Time to Christen my "NEW" system...
I'm thinkin' KISS's "I love it loud" then Mr Ted Nugent's Motor City Madhouse.
Thanks again guys,

GAV

 

Glad you got it fixed! Nothing worse than electrical noise in your sound system. Just as I suspected, the grounding was the issue, it usually is!