update on alternator noise over speakers

[Lawrence C Leung]

Most of these filters are choke coils (inductors). You want as much coil
as possible. You can connect more than one in parallel (i.e. + to + , - 
to - , and yes there really isn't a + and  - in a coil, but it's more
descriptive for those whom aren't as into electronics) to each other, but
in series to the circuit, AS NEAR AS POSSIBLE TO THE AMP/HEAD (i.e. coils
all connected together, in-line to the amp) to gain inductance. 

In ADDITION, you can also add a sizable capacitor into the circuit,
connected directly across the power terminals of the amp. Here + and -
matters, match + to +, etc. This type of filter is not commonly sold, and
due to the range of possible engine electric noise frequencies (most vary
by RPM) I don't know a way to calculate the appropriate value. I used a
2000 micro-farad MONSTER capacitor (left over from a project, sized about
the size of a soda can) cap on my 4KQ and it helped (but didn't
COMPLETELY) eliminate ignition noise. 

Generally, filters will only be very effective over a certain frequency
band (or in a car's case, RPM range). The trick is to find which
frequency range is the most annoying and tailor the filters to that
range. 

HTH, 

LL - NY 

On Fri, 08 Dec 2000 08:21:21 -0800 Avi Meron <avim at pacbell.net> writes:
>
>The only way I was able to reduce it to a manageable level (it's there 
>but
>very faint) is by connecting a "big ass" filter directly to the head 
>unit.
>Noise went down by at least 80%.