JL Mono+Sony 4channel=bad noise

**DA9B18C** · 03-08-2008 02:43 PM

ok, i have a JL monoblock amp+sub, no problems. when i add a Sony 4 channel into the picture, the JL gives off a horrible noise when the vol is down. a high pitched hum. i have hooked up several system's before and never this.

if i disconect the power to the JL the noise is gone?

JL-lowpass filter on
Sony-no filter on, when switched on it cuts out speakers?

question is, can i get a external filter for the power source to the JL?

the noise is killing me, whats wrong.

**JetSir** · 03-08-2008 05:28 PM

u prob didnt ground it right...

**davec** · 03-08-2008 05:57 PM

is it a whiney sound when the engine is on?
if so check your grounds make sure theres a solid connection between the cable and chassis also make sure that rcas are away from the power and ground cable

**DA9B18C** · 04-08-2008 06:59 AM

Originally Posted by davec

is it a whiney sound when the engine is on?
if so check your grounds make sure theres a solid connection between the cable and chassis also make sure that rcas are away from the power and ground cable

yeh, whiney noise that gets more high pitched as i accelarate.

will check

**Someone²** · 04-08-2008 01:54 PM

Yeh grounding is the big one, the noise seems to be caused because of a voltage difference between your earth for your Headunit and the earth for your amps, this causes a small ammount of current to travel along your RCA's in order to even this out, if you make sure your earths are really good you generally wont have this problem, another option is to run another cable between the earth of your HU and the earth of your amp, people have said that this reduces the noice, my guess is that it just gives another path for this current to travel other than your RCA's... Try it and see how things go.

**dupac->** · 04-08-2008 02:17 PM

Originally Posted by Someone²

Yeh grounding is the big one, the noise seems to be caused because of a voltage difference between your earth for your Headunit and the earth for your amps, this causes a small ammount of current to travel along your RCA's in order to even this out, if you make sure your earths are really good you generally wont have this problem, another option is to run another cable between the earth of your HU and the earth of your amp, people have said that this reduces the noice, my guess is that it just gives another path for this current to travel other than your RCA's... Try it and see how things go.

so what you're syaing is run from the earth of the HU directly to the earthing of the amp on the channel? or where its earthed to on the chasis of the caR?

**Someone²** · 04-08-2008 05:56 PM

Originally Posted by dupac->

so what you're syaing is run from the earth of the HU directly to the earthing of the amp on the channel? or where its earthed to on the chasis of the caR?

Not somthing i have done before, but basically giving the current another path to travel rather than down your RCA's...
Soo run the wire from the Ground wire on the HU to the ground wire on the amp...
It is more a bandaid fix rather than a proper fix. If your grounds are all good then you shouldn't get the noise

**dupac->** · 04-08-2008 06:14 PM

good stuff...

i always thought it was grounding that was the problem.. i always thought it was an urban myth never really tried it
lol

thanks

**DA9B18C** · 05-08-2008 11:28 PM

yeh, makes a hell lot of sense. will try it really soon.

**paps02** · 06-08-2008 11:58 AM

my car used to do this. just went away one day and havnt herd it since

**Someone²** · 06-08-2008 12:10 PM

Originally Posted by paps02

my car used to do this. just went away one day and havnt herd it since

Lol somehow i dont think this is the most relyable fix :P

**A.G.System** · 14-08-2008 12:58 AM

Originally Posted by Someone²

Not somthing i have done before, but basically giving the current another path to travel rather than down your RCA's...
Soo run the wire from the Ground wire on the HU to the ground wire on the amp...
It is more a bandaid fix rather than a proper fix. If your grounds are all good then you shouldn't get the noise

What you say is true.

Check your loom and disconnect the negative wiring and run a GOOD QUALITY cable to a new earth. Use the Chassis metal under the dash. This should clean up the noise.

Other thing to do is like others have said run your Power leads down one side of the car and your RCAs along the other. RCAs are highly susceptible to electrical cross talk and the further they are away from the power wires the better you will be.