whine in system that follows rpms, so confused

[madbouncy]

I finally got my amp hooked up. I listened to it last night with the car off as a test and it sounded good. Now I went to buy a fuse with the power off, then put the fuse in and on my way home. I noticed there's a really high pitched whine that follows my rpms. I read in the previous thread that it might be the ground? Though I connected the ground for the amp to the negative on the battery. I'd mess with the headunit but the whine is all dependent on the rpms. I figure the cables are too close to the power cable and are getting some noise. Is there anything you guys recommend I could put around the power cable to help shield it more? Thanks for your help.

[Rex]

Yea, the RCA's need to be as far away as possible from the power wire. I realize this is not always possible, but you may want to take another try. There are some better shielded RCA's available, but that would be some serious $$, and your labor is most liekly sheaper .

Also, make sure the ground is good, solid and short.

[madbouncy]

How short would the ground need to be? I ground cable is kind of long, probably about 2.5-3 feet. I could maybe make it like 2 feet if I ground it to the chassis where I grounded the battery instead. I'll mess ith the wiring tonight. Thanks for the reply though.

By the way, the amp is probably about a foot away from the batttery, is that too close? The actual rca cable are run on the opposite side of the car as the power cable. So I know that's not it.

[whosurdaddy018]

or your could just go to your local car audio shop and have them install a noise filter on your r c a cables that would be the easiest thing to do

[Rex]

I'd say that's a short enough ground cable, I like to try and make it less than 2 feet, but that's not always possible. Make sure the ground it secure to an unpainted solid metal section, and mayeb pick up some RCA filters as whosurdaddy suggested.

[Silvia2b]

Shorter the better, and even if it's closer to the battery than your headunit I would still ground it to you chassis rather than the battery. The reason is the ground path for the Headunit could be longer than the ground path for the amp, hence the ground loop interference you are getting. One solution that I know works in some cases and of course is dependant on the components installed in the vehicle is;To buy a 2200 microfarad polarized cap solder some leads to it and on the positive side place a ring terminal large enough to bolt to your alternator output post. On the side towards the direction of the arrows, or the negative side ground the leads to the chassis of the vehicle within 12" or so of alternator mounts. And follow the precautions Rex mentioned for the grounding point.

[madbouncy]

I'll try and do some of that stuff today. I'll make a grounding spot for the amp on the chassis, that'll also take like a foot of wire off the grounding cable. So far all I've noticed is that if I put the headunit to 0 volume, I still get the noise. However, if I unplug the rca cables from the amp, the noise is gone. So I dont' know if it's just cutting power to the speakers and that's why it's gone or if it's still powering them but the noise is in the rca cables. Also, it's alot worse ni the front speakers. I put the filter on for the amp, I had to set it like twice as low to get rid of the noise in the frotn speakers as the back speakers. So my guess is, whatever noise is happening is because of the path along the rca lines. I'll try and get that noise filter tomorrow if I can afford it. I'm working on a grounding kit for the engine. There's a stripped hole in the valve cover and then the tap broke in half in that hole, so that was put on hold. I can probably finish the rest of the kit and just leave that one wire out till I fix that though.

This is sort of how it goes. The amp and battery are in the trunk. I ran the rca cables and two speaker cables along side the drivers side of the car. It starts behind the head unit then goes under the steering wheel, then down under the carpet, then it comes up from under the carpet at the back seat, goe under the backseat and then up into the trunk. The amp is mounted to the back of the seat (it's a coupe.) I figure it's a problem along there because then the front speakers would have to run past whatever is causing the noise twice, where as the rear speakers would only go past once. Does anybody know of something around there that could cause a big problem? Also, there was a dc to dc convertor or something on the headunit, I put it as far away from the wires as I could but it was only like 3 inches away. Has anybody ever had that cause noise problems? Sorry for such a long post, thank for the help again though.

[madbouncy]

I guess this proves I am officialy a retard. The system sounds really clear now. I started messed with the settings on the amp some more. Before i just blocked off the freq the noise was coming in from, which also cut out most of my highs, was like listening to a speaker that had a lot of stuff in front of it, really muffled. Anyways, I saw a thing that said low volt and high volt, they both were on low, so I put them on high and turned the little sensitvity screw all the way to one side, it got rid of all the noise, it was a little bit quieter, but then again, it seemed suprisingly loud originaly for such low volume. 10 was practicaly louder than my stock and it goes up to 35. Now it's more normal where the volume is around 20s for where it gets loud. Guess I should've looked more into all the features the amp had before I installed it.

Thanks again for all the help guys. It's always the little things.

[ayjay]

ya most of the time when you have the gain turned up to high, you'll get the humming noise in the line... just outta curiosity, how many volts are the pre-outs on your deck?

[madbouncy]

4 volts

Also, i think I was wrong about the switch being volts, I think it might be impedence (can't spell.) I just finished putting in my brothers headunit which sucked because the electrical on his car is all messed up so it took me about 8 tries wiring the thing to find out that I need to combine the constant power and acc power wires all together. I feel bad for that car, it's been through so many crashes. I'll look at it next time I go outside to see what the switch was for. But I think it was impedence, i was half asleep and mostly pissed off so I was just doing whatever I oculd on the amp.

[drvr240sx3]

its not necessary to wire the constant and ign together. simply take a test light and find an ignition source in your fuse box and wire to there. that makes it work just like normal

[Silvia2b]

The reason amps would have an Impedance selector switch, is so that if you are using different speakers configurations. For instance if you have one single subwoofer, with dual voicecoils that are 2 ohms. In order to connect the amplifier for the best load you must set the amp to the 4 ohm setting and wire the subs voicecoils in series with each other. Most amps are capable of this function automatically however. Or it is possible that like some German makes and now general motors there is no accessory wire in the radio harness because they use a data bus turn on and delayed accessory power. What kind of car does your brother drive maybe we can help you fix the accessory issue so it doesn't accidentally kill his battery the first time he leaves the radio on. Let us know.
Modified by Silvia2b at 10:47 PM 1/18/2005