Alternator noise to power AMP
audi at humanspeakers.com
Tue Apr 5 18:51:15 EDT 2005
> As you predict - disconnecting the shield wire amp side makes no
I meant to say this earlier, but I suspect the wire you are referring o
has nothing to do with grounding or shielding - if the RCA cables were
intended for auto use, they may have had an extra conductor to serve as
the amplifier switching lead.
The shielding itself will always be under the insulation and completely
around the inner core. On simple cables, it is also the "-" conductor
and is connected to both plugs. This can lead to ground loop problems,
especially in a car.
"Directional" line level cables have two conductors in the center for
the signal, and a shield that is only connected (internally) at one end.
> The amp was already wired directly to the battery both + and ground.
> I ran a separate ground to the chassis ground point in vicinity/trunk
> and back to the amp so now it connects both to battery ground
> directly and the chassis ground nearby - this also returns back to
> the battery through a different path in the car. This made a
> significant reduction in the whine, but it is still present.
Try grounding the head unit to the battery directly, also. I deally,
everything should be grounded to one place, and only one place.
> The amp still "clips" and I am beginning to believe that a cap may be
> in order.
That sound like a weird band-aid. How much power is the amp supposed to
generate? You mentioned a 10 ga ground lead, that's good for about 300
watts at 12 volts. Have you measured the power supply voltage on a fast
acting meter at the amp while it is running hard?
> I still need to check the shield ground at the head
See comment above...
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