I just got my JL Audio 300/4 back from repair due to a front right channel giving out distortion. I also had a good (well not good) humming coming from the speakers. I put it back in the car and find out that i have the same humming. I rip the entire trunk out to get to the grounding point and find out that the people who did my glass work moved the ground and did not even strip the paint. Well i stripped the paint to bare metal and put everything back in. I turn the car back on and it is still there. I rev up the engin and i can hear the alternator speeding up through the speakers. I know i have a good ground for the amp. What else could be my prob. I am sorry if this has been brought up already, i looked and didnt find anything.

 

things to try how do you have the rca installed oem deck or after market? that amp doesn't have a line level in it so were and what are you doing to get the rca. If you have wires(speaker) crossing the power this can cause that sound. Also I have had a new line level that was crap out of the box that also can make nosie. Older crappy cables can cause the sound move the xover point. I know in old phoenix gold amp that was a problem also
I own the jl slash300/4 and 500/1 first gen. and never had a problem
best of luck but there are a couple of thig to try

 

well i have taken out the LOC for the subs, i have a 9 wire cable running from the stock amp to the JL, going into 2 sets of rca's for the amp. when i first wired it up i had no issues it took about a month before it came to be the way it is now. It sounds like it is a ground issue more than anyhing else.

 

is the power lines running next to the rca's?
if so, run them a different route..away from the RCA's and see if that'll do the trick.

 

Do you have multiple ground points, I like just the one source

 

I only have a short run of rca for the subs, i slpiced them into the wires for the stock sub. The 9 wire cable that is running from the stock amp to the 300/4 amp is running down the opposite side of the car than the power wire. I am only using one ground point and i know it is good. I tested the continuity from the ground point to different bare metal points on the car. The sound is annoying me so much. I want to tear out everything and redo it all but that is time consuming and i want to make sure that i fix the problem. But without knowing what the problem is, i am not sure i would correct it.

 

thats the reason why you getting a humming sound on ur speaker. your rca is not install right. and what kinda wiring did you use?

 

I am using a nine wire cable (forgot the brand) spliced into the stock amp output wires, and then rca's (JL Audio) spliced into the other end to go into the amp, i know everything is hooked up right. What do you mean that the rca's aren't installed right. Like i have one rca spliced backwards (positive to negative and negative to positive)?

 

Do you have the input voltage switches in the "High" position?
How are your gains (input sensitivity) set? They may be too high.

 

the switches are set to a high level input. the gain isnt too high. I think when it gets a little warmer out i will check everything again, cause ever since it got cold outside it has gotten worse and then starts to fade out once the car get warmed up. Maybe that can give someone a clue to what my problem may be.

 

Not sure if I understand you but you cut the RCA and spliced into the sub output?

RCA's are usually not best spliced as there coating usually causes interference, just from experience. I would say to get a quality LOC(david navone comes to mind although its been a while) and wire the factory sub to the LOC, get new RCA's from the LOC to amp and see if that solves your issue.

 

I do have rca's spliced into the sub wiring, but the subs are not my prob. I have a cable running from the output of the stock amp to the trunk of the car. This cable is tapped into the output wires of the stock amp and then spliced into rca's so that they can be connected to the amp for my regular speakers.

For a little more info, i drove my car lastnight since the roads were pretty good and realized i forgot to mention that the humming gets louder and higher pitched when i press on the throttle. If i remember right this is usally caused by a bad ground. By my ground is as good as it can get without welding the ground wire to the body of the car.

 

Try tapping your RCA's at the input of the stock amp rather than the output and then readjusting input voltage and sensitivity on your JL amp accordingly. The stock amp could be introducing noise into the system that is just being amplified by your amp.

Also, even though your aftermarket amp ground may be clean, you can still have a ground loop if the grounds from the other components in your system (headunit, stock amp, etc...) are in different spots with slightly different potentials. If there is any resistance (it doesn't take much, and can be caused by welds, dis-similar metals, etc...) in the chassis between any of the grounds you will have a ground loop, and therefore noise. The best way to avoid that is to ground everything in one place.

I chased alternator whine in my system (in my RSX) for nearly two months. As a last-ditch effort, I reset my gains (correctly) to a lower level and the noise disappeared.

Good luck in your efforts! These things can be very frustrating.

 

I will try resetting the gains to a lower level, evne though the sound started and i never touched them, but hey, i have tried everything else. getting the headunit and everything to the same ground point will take some doing, so if the gain thing doent work, i guess i will route a wire from the stock raio ground to the amp ground point.

 

Same thing happened to me. My system was in for a couple of months before the noise came about.

If you haven't already, go over to the forum at http://www.diymobileaudio.com/forum/ There's a huge wealth of information over there that might help as well.