Ferrari Mailing List: Re: More Stereo Installation & Wiring Expertise Needed

[Robert W. Garven Jr. (rgarven]

Friends,

I am running solid core magnecor wires on my 308 and the car has run  
unbelievable They are also black and look great. No points wear, never  
not started, never any problems, no plug fouling nothing! I recently  
have been trying to install a stereo for over 3 months and am at my  
wits end. I am wondering what wires any of you GT4 or carb 308 guys  
are running the book says 107364 & 107365. I really dont like the red  
color and frankly forgot how to install a non solid core wire! I have  
a new set of 114473 & 114474 they are black but they say they are for  
an injected car or mondial? The wire says CAVIS 400 CLASSE B. It looks  
like it has a spiral wire running inside of the insulation, which to  
me does not seem like enough wire. Can any of you give me some  
feedback on what you are running and how to connect these wires. I  
assume that these injected wires would not be suitable for my carb  
GT4???

I feel like a real girlie man going with the resistor wires but I have  
invested so much time in this stupid stereo project that I am desperate!

BTW I am running non resistor extenders and NGK non resistor plugs


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






On Apr 28, 2009, at 6:24 AM, Charles Perry wrote:

> Robert -
>
> I can't see in your F-List or F-Chat posts that you replaced the  
> speaker
> wiring at any time. While I don't think that the speaker wiring  
> would be
> bad, there were several wiring schemes on older cars that could cause
> the problems you are speaking of. I have never worked on a GT4 so I
> don't know if they apply.
>
> Some older cars used a common negative for each pair of speakers,
> meaning that they each had their own positive and then they shared a
> negative back to the head unit. While you may see two separate  
> negatives
> at the head unit, there's no guarantee that they are independent all  
> the
> way back to the speakers.
>
> In some really old cars, the car chassis was the negative for the
> speaker wires.
>
> This worked fine in older head units where there was a single sided
> power amplifier in the head unit. However, newer units like your  
> Kenwood
> have two amplifiers for each speaker. They are wired out of phase and
> operate in a push-pull configuration to send more power to the speaker
> than you could otherwise get from just 12-volts with no switching  
> power
> supply. These amps are intolerant of common ground or chassis ground
> configurations because you are essentially shorting two amplifiers to
> each other or to ground under those conditions.
>
> As to why it only happens with the car running, I have two guesses.  
> One
> is that one of the power leads you tapped into is hot under some
> circumstances and ground (rather than open) under others. This can  
> only
> be verified with a decent multimeter. The other is that when you start
> the car, you move from battery voltage (around 12.5 in a healthy
> battery) to alternator voltage (around 14.4v in a healthy alternator).
> This pumps up  the power output to the speakers by as much as 15% and
> may be enough to put the amp into Protect if you have a bad situation
> that is on the border of the protect trigger with the car off.
>
> I would get your multimeter and set it on ohms first. Check each  
> speaker
> line (between pos & neg) and you should get roughly 4 ohms (+/- 20%
> would be normal depending on brand of speaker). Next, take the meter  
> and
> check every individual speaker wire lead (positive or negative)  
> against
> the leads of all other speakers (pos & neg) one pair at a time.  
> Under no
> circumstances should you read anything but open circuit (infinite
> resistance) between legs that aren't going to the same speaker. If you
> do, that's a problem. Let me know which leads show resistance to which
> other legs and we'll go from there. Next, check every speaker wire leg
> (pos & neg) against the car chassis. You shouldn't read anything but
> open circuit anywhere. If you do, that's a problem.
>
> -- charles
>
>
>
> _______________________________________________
>
> Charles G Perry IV
> Vice-President, Engineering
>
> Carolina Sound Communications - MuzaK
> 7630 Southrail Road, BLDG B
> N. Charleston, SC 29420
> (843) 571-4488         www.carolina-sound.com
> _______________________________________________