68 NJConv 454

I get some static noise coming from the front speakers. Trying to trouble shoot and fix it. Its noticable when the car is off...not when the sidepipes are in full effect
Here's what I got....
Pioneer headunit DEH-P7700MP
Cadence 6.5 component set with crossovers
Cadence 4ch amp (think it was 3004)
Bazooka bass tube.
Headunit and amp both power and ground wires were run straight to the battery up the center consol. The cadence amp was wired to the headunit via RCA cables for both the front component speakers and sub. Component speakers are on the first two channels and sub is on the + of channel 3 and - of channel 4. The sub wires run along the outside of the passenger side so its away from the power/ground wires.
I used very good $ RCA cables for the speakers and everything is wired correctly. The headunit ignition source is connected to the power wire on the stock radio harness...which for some reason powers the damn headunit as long as the battery is connected regardless if the ignition key is in the off position.
I get the static whether I use the radio, cd or ipod. Its just something I can fiddle with. Once the volume is up past 3 or 4 the static is drown out and the speakers really kick, especially that sub.
Any advice??

tjhuyser

Before i start, I am assuming you have check all grounds, and I'm assuming that it is not alternator noise, because it doesn't go up with the volume and the pitch doesn't change with RPM's...the wires going from the amp to the speakers, are they shielded?? try that, where is your ignition? is it an MSD somewhere near the dash?? that might be causing the interference...even with the car off if there is juice to the MSD it'll be running.....if shielding doesn't work, pull all the fuses out of the fusebox except for the stereo. if it doesn't have any static, start putting fuses back one by one until you have the circuit isolated that is causing the static, then check the grounding on that circuit, then start checking the electrical devices on that circuit.

shafrs3

Does it come from the radio and the CD?

Any sources of EMI or RFI near by?

68 NJConv 454

The ground is at the battery. So no problem there.
I have an HEI distributor but I get the static even when the engine is not running or the ignition is still in OFF. The actual speaker wire that runs from the crossovers to the speakers is the standard speaker wire that came with the Cadence component kit. Static does not increase or decrease with RPM's or volume, although I wouldnt' really be able to hear the static over the sidepipes anyway.
Good idea with the fuses though. I'll give that shot.

68 NJConv 454

No garage, just a tent.
What is EMI or RFI?
I get the static no matter what I am playing, radio, cd or IPOD and the volume is at zero to 3. Once I get the volume at 4 the sound overpowers the static.

shafrs3

Electromotive interference and radio frequency interference. The first can come from electric motors or welders, the second can come from florescent light ballasts, like a drop-light nearby.

tjhuyser

try wrapping the speaker wires in aluminum foil...thats shielding...see if that helps

RunningMan373

I'm going to geuss it's coming from you Cadence amp. Amps use an internal switching power supply to extend the voltages way above the 12V available in a car. +/- 35V is not uncommon. If the amp isn't filtered well, internally because of some production problem, that is what you'd get. With the Car off, but problem present, Unplug the RCA jacks (all) to the Amp, if the problem remains it is probably in the amp it self. If not, it could also be coming from the head unit by way of the RCAs, pull the power to the head unit (ALL power) and see if it goes away. If it does, try putting a 100uF capaitor And a 0.1u f cap in parrellel right at the head unit power to ground wires. Try the amp first though.

there isn't enough power in a system of crossover/speaker wire/speaker to cause the problem, the problem is coming from one of the powered units.

68 NJConv 454

No welders or electric motors running at the time.
I do have drop-lights so I will check to see if thats the problem.
Don't remember if I had one near me at the time.

Hummmm.....When I turn the headunit off the speakers don't make any noise. If I turn the amp off, won't that have the same affect since the speakers are connected to the crossovers which are connected to channel 1 & 2 on the amp??
I think I see what you're saying...if I yank the RCA cables to the amp and the speakers still hiss then its the amp causing the problem. right?
If it stops then maybe the headunit is the issue.

I have no more $$$ to put into a capacitor or sound system modifications. And I don't have the energy to remove the dash again to get at the speaker wires that I ran along top .
I'll trouble shoot some more after work.
Thanks guys.

RunningMan373

No welders or electric motors running at the time. I do have drop-lights so I will check to see if thats the problem. Don't remember if I had one near me at the time.

Take the car out a block or so away from the house, middle of a parking lot somewhere and see if the problem persists,, if not Probably florescent lights.

Hummmm.....When I turn the headunit off the speakers don't make any noise.

This means that the problem is coming from the head unit 90% sure.

If I turn the amp off, won't that have the same affect since the speakers are connected to the crossovers which are connected to channel 1 & 2 on the amp??

No, because the reason for pulling the RCAs is to check the Amp for the problem.

I think I see what you're saying...if I yank the RCA cables to the amp and the speakers still hiss then its the amp causing the problem. right?
If it stops then maybe the headunit is the issue.
Yes,, try this anyway, though it sounds like the head unit is were the problem is originating, just a good check. try driving to a parking lot, like above too.
You may of also run your head unit power wire too close to a emf source in the car.
Good luck,,C