RU9 wrote:
>
> Before I replace my power supply because it produces an
> audible hum (speakers) after connecting it to the soundcard.
>
> Please recommend a solution to eliminate the hum?
>
> Thanks.
>
> Luis Matias

I take it from your domain that you are overseas so this may not apply,
but it is still possible.  AC hum can be caused from two different
systems that do not have the same polarity of AC power applied to them.
(How can AC have polarity when it is alternating?  Easy, one line is
considered HOT and the other is considered NEUTRAL.)  Power pack units
typically have transformers in them and they _should_ provide isolation
between the AC and the DC output.  However, because no two packs are
alike, I don't trust them.  If your computer is plugged into one outlet,
and the power pack is plugged into a different outlet in a different
branch, are you sure that the "hot" wire of both outlets are on the same
side of the outlet?  In America, before there were three wire plugs and
outlets, or two wire polarized plugs, problems with AC hum were common.
Turning the plug around from one of the devices would typically
eliminate the hum.

If you don't feel confortable checking or testing the ac power system in
you house, maybe you could find a friend who is experienced with
electricity to test your power system.  They could also test that power
pack to see how much AC ripple was present on the DC output.  If it is
excessive, you probably do have an el-cheapo power pack and it may be
helpful to purchase a better speaker system.

But my bet is the ac wiring is causing your problems.  Test it first.
--
Jean Bourvic :>))

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