"Arny Krueger" wrote in message
...

Everbody should forget damping factor which is a joint property of loads
and amps, and just talk about amplifier source impedance to its load,
which is purely a property of the amp.

Agreed Zo is a figure that is pertinent to the amplifier, but
DF is important because the amplifier and its cables, plus
the speaker which it is driving should be regarded as an
entity when judging system performance.

If you know something about the load, its easy math to turn source
impedance numbers into damping factors.

Arny. Have you come across the writings of the legendary
British audio engineer Norman Crowhurst ? (He has published
several books and countless articles)

He states that the conventional method for DF measurement
Speaker impedance/Amp output impedance (Zspkr/Zo)
is incorrect,as the DC resistance of the voice coil should also
be taken into consideration, since it is a limiting factor in DF.

Using a value of 8R for the impedance of the speaker and
6R for the DC resistance, and an output impedance of 0.5R
we get:

Zls/(Zo+Rvc) = 8/(0.5+6) = 1.23.
Calculation by the traditional method gives: 16

Food for thought
Iain