On Mon, 6 Mar 2006 22:07:51 +0000 (UTC), "Jo"
wrote:

In ,
harrogate2 typed:

It is nothing to do with the speaker load impedence, rather the amp
output impedence.

When the loudspeaker cone is extended by signal, if the signal is
removed then it is down to the mechanics of the cone mount to return
it to its rest position - except that it won't, it will follow a
decaying oscillation path. During this time, as the voicecoil is now
being moved mechanically in a magnetic field it becomes a generator,
so the lower the load that it sees - in this case the output impedence
of the amp plus cable resistance - the quicker the energy will be
dissipated. As an amp output impedence is typically around 0.1R (or
less sometimes) then the resistance of a thinner cable can become
significant, hence why thick is better.


I don't see that. In addition to the output stage of amp and cable the same
current is *also* flowing through the speaker coil itself, they are all in
series. Therefore it is in the speaker coil where most of the energy is
dissipated, assuming that the output impedance of the amp is, indeed, low.
And also assuming that the cable resistance is low compared to the speaker
impedance. It follows that the cable resistance should be low compared to
the *speaker* impedance because it is this that has the major effect on the
overall output circuit energy dissipation and hence damping factor.

I see the setup as being analogous to a generator with a short circuit on
the output terminals, or a very low resistance load. The windings of the
generator heat up and dissipate more energy than the load.

But I do agree that thick cable is better :-)

Congratulations, you understand pretty much everything you need to
know, and you hit the nail on the head regarding 'damping factor'.
It's about power dissipation - and FR imbalances because the speaker
is designed to be driven from a low impedance.

--

Stewart Pinkerton | Music is Art - Audio is Engineering