2 replies to this topic

[MuSkY]

Hey guys,
The other day i fitted a response 4 chan amp into my BA ute using an REQ5 loc. Everything went fairly smoothly except for the dreaded whine coming through the speakers. Now i did miles of research as my grounds are solid, the req is grounded at the same place as the amp (according to the req5 manual this creates a ground loop isolator). RCA's are only 500mil long and no where near power so theres no chance of interference through them.
Now i read some people had success with the jaycar noise filters, and at 15 bucks i thought i'd have a crack.
So heres my first question: Using the stock ICC unit, how do i install one of these? There are three wires, ones for the 12v constant, ones for ground and the other is for the 12v constant from the head unit (i've added a pic to make more sense), if im to use this noise filter where can i get this wire from?

Now whilst i was looking around behind the ICC for the 12v constant, i remembered reading about unplugging rcas/speaker wires at the amp to see if the noise stops, so i unplugged rcas and the noise stops. OK, plug them back in and unplug the speaker wires, noise stops! Does this mean im getting interference from the speaker wires? I've run the power from the bat through the center and speakers down the drivers side so thats not a prob. I did notice that there are wires running down the drivers side for the drivers seat adjustment as well as the antenna cable, could these cause interference in any way?

One other possibly stupid question, is there any difference between the red power cable and brown ground cable you buy? Reason im asking is i've used a short length of red power cable for my ground to my amp as i didnt have any brown ground cable.

I know people on here have had some drama with the ICC's in the falcons and have opted for an aftermarket head unit, but there doesnt seem to be many solutions other than this.

Thanks

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[TMM]

That filter is designed to be put inline with the amp and/or LOCs power cable from the battery. I've never used one myself but i think it's mostly to remove alternator noise caused by the alternator itself rather than a ground loop. ANy half decent amp will be able to cope with this noise by itself. Make sure it is of a sufficient power rating for your amp before hooking it up. 10A max would suggest that the one you have is only designed to work with headunits rather than power hungry amps.

You can also get ground loop isolators that go inline with the RCA cables.

Try moving the LOC away from the amp and any power cables - sounds stupid given that it is powered itself, but there could be some coils in there picking up noise caused by the amp drawing current.

Also try grounding the LOC in a seperate place to the amp (avoids noise caused by the amp 'starving' the chassis ground point) and run an extra ground cable between the headunit's ground and the loc/amp's ground.

Speaker cable interference is less common, and usually only affects very sensitive speakers and tweeters. If the noise goes away when you diconnect the RCAs from the amp, that would suggest it's not the speaker cables.
You can test for speaker cable interference by leaving everything plugged in but driving around with the system powered off - disconnect the remote wire from the amp if the headunit isn't able to be turned off with the car running. I did this in my car and still got some faint whine through the driver side speakers when driving around. I routed my drivers side speaker wires under the dash board and up the passenger side to avoid the amp's power cable and this solved it.

Passive crossovers are also good at picking up noise, so if all else fails try moving them to different locations.

Edited by TMM, 12 January 2012 - 07:51 PM.

[sphell]

Does the Response amp have hi-level inputs? If it does, I would suggest getting rid of the LOC and run the speaker wires from the headunit directly into the amp. The higher input voltage has a better chance of rejecting noise. How have you set the gains? If they were turned up while the factory headunit wasn't at near full volume then you will increase the noise in the system. Otherwise if you've tried this and everything TMM suggested, it could just be the amp.....often the cheaper amps won't have the noise suppression of the better brands.