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[email protected] dpierce.cartchunk.org@gmail.com is offline
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Default Motional feedback in speakers

On Thursday, November 7, 2019 at 2:41:04 PM UTC-5, Peter Wieck wrote:
Take the (permanent magnet) speaker as a linear motor.

Now, for illustrative purposes, obtain a small DC brush-type motor.
Spin it with your fingers. Now, short the leads to the motor.
Now, try spinning it again with your fingers.

Not so easy.

That is the function of "damping factor" - As a way to prevent a
PM speaker from wobbling like a spring when it is released.


Cute analogy, but FAR from the physical reality of speakers.

Start by inserting a 6-ohm resistor in series with the
lead to the motor. Make sure it's PERMANENTLY connected
and can't be bypassed. Pretend that's the DC resistance
of the voice coil.

Try to spin it with your finger. Easy, right?

NOW short it (making sure that 6-ohm resistor is still in
series).

Try to spin it with your finger. Really, how much harder
to you think it might be (hint: not much).

Take your same motor, but pack the bearings with thick grease.
Now, try spinning it with your fingers. Not so easy.

So, if you want your little experiment to have ANY connection with
the reality of a speaker, that's what you have to do.