[Don Pearce[_3_]]

On Fri, 26 Apr 2019 23:31:34 -0700 (PDT), wrote:



What has the resistance of the voice coil got to do with this? It is a
parasitic that produces nothing but heat. It is the resistive vector
of the reactive component that is of interest here.



** The topic is measuring *power dissipation* so resistance is everything.

The power dissipation in a loudspeaker is approximately 85% in the voice coil with the remaining 15% in the suspension, eddy currents and radiated sound.

This is starting to get quite surreal. The current that flows depends
on the impedance, not the resistance. At some frequencies the
impedance is higher, resulting in less current. At others it is lower,
making more current. At the resonant peaks the resistance (not
reactance) of an 8 ohm speaker can approach 50m ohms. Between
resonances at is probably down around 4 ohms.

Take a look at one of my measurements of a speaker - a Mission 774.
There are two plots. One is scalar impedance, and the other is the
full picture on the complex plane. If you can tell me what resistance
I am supposed to multiply the current by on a broadband signal I will
give up.

http://www.soundthoughts.co.uk/look/mission_imp.png
http://www.soundthoughts.co.uk/look/Mission_complex.png

d