Ferrari Mailing List: Re: Need help with stereo in Ferrari

[Jeff Greenfield (coyote]

Here is one place that you can get a Ground loop isolator, Radio Shack used
to have them as well so you may want to check there. 

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=265-012

Here is one article regarding ground loops:

http://www.crutchfield.com/S-2hHzDSF8VrX/tech/kb348.html

and another:

http://www.bcae1.com/glisoltr.htm

And another resource on troubleshooting noise:

http://www.crutchfield.com/S-2hHzDSF8VrX/tech/kb1815.html

It is always best to ground all components at the same point, but this does
not always work. Often the chassis of the head unit is common to ground, and
if the case is in contact with any metal of the dash this too is common to
ground. Also, the antenna is grounded to the body, so the head unit is also
connected to ground through the antenna cable. 

Here is some more info on isolating noise:

http://www.mobileaudio.com/rac-faq/

Somewhere I have some articles that specifically address ground loops but
cannot find them at the moment and how to identify if this is the problem,
but cannot find them at the moment. 

Lastly, why not give crutchfield tech support a call?

Jeff


-----Original Message-----
From: Robert W. Garven Jr. [mailto:rgarven [at] gmail.com] 
Sent: Saturday, March 07, 2009 9:06 PM
To: Jeff Greenfield
Cc: The FerrariList
Subject: [Ferrari] Need help with stereo in Ferrari



All,

I bought a blaupunk small subwoofer to try to make the samll speakers  
in my gt4 sound better, I am having a problem and know that there are  
a few electronic experts here!


I took everyones advice and ran a 10 gauge wire from my battery to the  
subwoofer, with a 10 amp fuse around six inches from the post. I spent  
around 4 hours removing the screws, seatbelt, shift gate etc so I  
could access the underside of the stereo. I hooked up all the wires  
and before i put it back together I mage sure it worked and it sounded  
great. Fast worrward 8 hours putting everything back and cleaning etc.  
I pull the car out of the garage
fire it up and evenj with the stero off I get a loud crackling through  
my speakers! I unhooked everything one wire at a time and it seemed to  
be the expensive street wire RCA cable that attached from the back of  
my cassette deck to the subs RCA inputs!

I removed everything again and this time cleaned up all the wire under  
the radio etc and tried a rockford fosgate shielded RCA cable this  
time started up the car and no crackling!! Great!! I put everything  
back together ( again) and pull the car out of the garage and this  
time the sub is making a weird gurgling sound, I remove the RCA plugs  
and this reduces it but it is still there.

Here is my problem?

I am running solid core wires and NGK BP6ES plugs. I know. I know, but  
the car runs great with the wires and I will do without the sub before  
i remove them! Will a resistor plug solve my problem?

Remember my stereo (cassette) never had any noise ever (the radio did  
but I dont listen to that). The sub has high powered speaker leads  
which I could try but the unit is obviously making weird nosise with  
only the power attached an no inputs so I am nt sure that would be  
much better. This thing sounds great with the car off and gives just  
enough bass to make the 4" speakers sound great. I anyone has any  
suggestions.

I know you guys are going to say no but it seems that interference is  
coming from my ignition being picked up by the power wire and the RCA  
cable (but the cassette sounds fine). Since this is such a small 70  
watt unit why cant I hook it up to the same power wire that my  
cassette is hooked up to eliminating the 10 gauge wire.



Rob

Thanks for all your help in advance. If a resistor plug might work I  
would like to try that as changing plugs is about 10 times easier than  
removing the console again!!!

Robert W. Garven Jr.
rgarven [at] gmail.com


  "The Ferrari is a dream - people dream of owning this special  
vehicle and for most people it will remain a dream apart from for  
those lucky few". Enzo Ferrari





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