Damping factor explained - or not?

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a transconductance amp appears as an ideal current source with a resistor in parallel but this not what a motor control amp does because it has negative feedback which means that the "back EMF" cannot induce any current as this is cancelled by a current in "opposite direction" thus that the total current is defined by input voltage. I think that is
perfect damping.
 
a transconductance amp appears as an ideal current source with a resistor in parallel but this not what a motor control amp does because it has negative feedback which means that the "back EMF" cannot induce any current as this is cancelled by a current in "opposite direction" thus that the total current is defined by input voltage. I think that is
perfect damping.

Try an experiment, drop a big super-magnet down a copper pipe (no amplifiers no electrical feedback), observe damping. This is the same thing that happens with a shorted voice coil and motor assembly.
 
Try an experiment, drop a big super-magnet down a copper pipe (no amplifiers no electrical feedback), observe damping. This is the same thing that happens with a shorted voice coil and motor assembly.
Zero D

Works with aluminium too
You bet, I test that every day, since I commercially make guitar speakers and in half the models use voice coils with aluminum formers because they stand more abuse than kapton or Nomex (let alone paper).

They are gapped but *still* show eddy currents.

Just as a routine, when I put them on the assembly bench face up, I drop an aluminum former voice coil in the gap; if it's magnetized it drops like through honey; if not, like a sack of potatoes, at free fall speed, *very* noticeable difference.
 
Just look at the DF as an electric brake.
Thre DF is trying to hold the diafragm at the position wich the amplifiers input signal determines.
The mechanical mass of the diafragm and voicecoil will try to continue its movement as all moving mass would of there was no friction or other forces to dampen them.

For a speaker this means the diafragm will be swinging back and forth as the suspention for the diafragm keeps it in the speaker.

Luckily the DF will dampen it further, making that bass tight and dry whenever a good amp is connected.

The DF is to be looked as a parallel "impedance" with the speaker.
 
First of all, this reply is not meant to educate readers of this forum but rather to give a "layperson" explanation which A Makes sense and B is factually correct.
Damping factor is calculated by dividing the loudspeaker impedance, which changes with frequency, by the real impedance of the power output stage. The lower the O/P stage impedance, the better as this will effectively short circuit any back EMF generated by the driver coil moving in the magnet when the 'explosive' signal stops. There are a few other factors involved here obviously, all of which have been mentioned previously. I have also used (with some success), the analogy of air in a hydraulic line EG spongy car brakes. This can sometimes serve to explain D.F. to a mechanically minded person.
Please read the first sentence again.

Cheers Neil;
 
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