alternator whine after amp and rf 3sixty.3 install

jlam86 · #1 03-03-2013, 07:58 PM

Hello fellow x5ers,

I recently installed the rockford 3sixty.3 Processor along with my audison lrx5.1mt amp and I have nothing but a ton of noise. I get floor noise from the sub (hissing) and a ever so slight alternator whine.

my amp and processor are grounded to the negative terminal of the battery. I ran a new ground from the factory deck to the chassis to bare metal. Still whining.

I measured 20.9ohms from the deck casing to negative terminal before grounding the deck. Now that i regrounded it, it is 0.9ohms. Should I splice into the ground going from the deck to the factory amp and ground that to the battery as well??

I am at a lost for things to do and it's pissing me off.. HELP!!

TerminatorX5 · #2 03-03-2013, 11:34 PM

what type of wires did youuse for the install? I would recommend using shielded wires with shields properly grounded at one end (if you ground at two ends, you may create a difference in potentials between the ends of wire, defeating the idea of grounding). In this particular case, you may have the sound wires lay alongside power wires, or maybe even criss-crossing them - your wires are picking up some induction... To eliminate it, you might want to wrap each sound wire in metal (aluminum) tape, and then wrap the wrapped wire in insulating material, to avoid the exposed metal jacket to short something somewhere... thus, effectively creating a shielded wire, but rather with a home-grown solution...
one other option is to use magnetic rubberized sheets, cut in long slices, and use them to wrap... all of the above is ugly for sure...

or..

i may suggest using Belden 9451 SB cable for this purpose... or similar...

jlam86 · #3 03-04-2013, 01:47 AM

my rca cables are triple sheilded phoenix gold wires and they aren't running along power wires. they pretty much run from one side of the trunk to the other.

For the high level inputs off the factory amp, i used "oxygen" free speaker 16awg speaker cable and that is only like 1.5 foot just to extend it from the factory amp to my signal processor.

do you think it is worthwhile pulling a wire from the front where i grounded the factory deck to the negative battery terminal in the rear?

as for the floor noise from the sub, when i disconnect the rca wires to the amp, it still has the floor noise so i am pretty certian it is internal circuitry of the amplifier.

TerminatorX5 · #4 03-04-2013, 01:55 AM

you grounded something in the front to something in the back? try to make grounding wires as short as possible - there several designated grounding points under the glove compartment with comb style connectors - use them. it will not completely eliminate the issue but will reduce the influence.
can you use shielded cable for the speaker's 1.5 foot line? try that too...

tell us if you get any improvement, if not, we will dig further...

jlam86 · #5 03-04-2013, 02:11 AM

i grounded the deck to the chassis right behind the deck. the ground cable i used is less than 8inches long. It didn't make a difference. the alternator whine that i hear is quite quiet, but it's when you have the volume abnormally low, you will hear it. I still am determined to get rid of it altogether.

i didn't know you can get sheilded speaker wire cables.

but even when i disconnect the speaker cables going INTO the amp, so it's just the amp and the speakers it is driving operating, you will still hear the whine. Shouldn't that elimate what is upstream of the amplifier...at least for now.?

TerminatorX5 · #6 03-04-2013, 02:21 AM

i don't know about special shielded wires for speakers, i think it is a marketing gimmick for speaker wire to begin with - audio signal is normally maxed out at 20000 Hz (human limit), and most wires can handle 20 kHz... the special design is needed for super high frequencies, we don't worry about them here... gauge is needed to pass amperage... so? you can get any shielded wire (coax Sat cable will be fine, it can pass upto a THz)? it is not convenient to work with though...

How do you power your system? are the power wires shielded?

jlam86 · #7 03-04-2013, 02:26 AM

the power wires are your standard 4awg amp wiring kit power wires as is the ground cable. both are less than 1.5ft long. the amp is pretty much located next to the battery.

I will look into getting some shelided cable for the high level extending in place of my current oxygen free speaker wires. is there a particular gauge for the coax sat cable i should get?

TerminatorX5 · #8 03-04-2013, 02:34 AM

what amperage are you expecting to drive? coax cables usually single core (one wire), you need something with dual core... it will not be called a satellite cable...

check Belden website, they have filters where you can narrow down your criteria, get the belden wire number and then search for a suppplier of that model cable... sounds complicated but it is not... that cable number that i gave earlier is for signals, so it is very thin... you will need something thicker...

your present speaker wire is 16 gauge... i will try to look it up tomorrow at work, or you can do it yourself...
what gauge your present power wires?

jlam86 · #9 03-04-2013, 05:31 AM

it just needs to be the same size as the factory speaker wires. so 18-20awg?

I looked at the belden website but not sure which one would really suit me with all the various descriptions. here is the info i found...
Speaker Cable

TerminatorX5 · #10 03-04-2013, 07:31 AM

6200FE seems as a good wire - it is 16 gauge as the ones you are using, it has a shield and a drain wire, has nice capacitance and low resistance, maximum operating voltage is 300 V RMS, so it is OK for car applications, can take 6 A of current it can be used for the signal AND power...

Now, you need to see if you can find a seller who sells this in small quantities, as the cable is commercial...