G Graham wrote:
> You are correct-- the other terminal on the speaker should be the ground
> (or shall we say "earth"). Some radios run a ground wire with the other
> speaker wire.
Just a note that when your stereo runs two wires to the
speaker, neither is likely ground.
Lower end stereos have only one speaker wire. The reason
is that they produce a signal, and then feed it through a
giant cap on the output stage. This way, they can provide
a positive and negative voltage swing at the speaker. Reference
to ground, this drives the speaker both in and out.
The drawbacks to this method are the non-linear output
stage which limits purity, and also the giant turn on
transient (THUMP) to charge that big cap. Your Kraco is
likely this type.
Most better systems use push-pull output circuits, which
means they produce a voltage difference between two
similar and matched circuits. Each is sent to one terminal
of the speaker coil, and the voltage difference between
them ranges from positive to negative and drives the
speaker both in and out.
Usually in these systems though both wires are usually
positive with respect to ground at all times, so connecting
one to ground is a Bad Thing.
--
Trevor Boicey
Ottawa, Canada
tboicey@brit.ca
http://www.brit.ca/~tboicey/
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