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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 3:51:05 PM UTC-5, Trevor Wilson wrote:

**No. It doesn't work like that. In a PROPERLY designed enclosure,
so-called "damping" is not dependent on amplifier output impedance.
Damping is supplied by the enclosure itself.


Nope, the enclosure supplies NO damping at all. Maybe the
internal fibrous fill provides a little, but the enclosure,
that is, the volume of air that goes through compression and
rarefaction as the cone moves, provides absolutely no damping
at all.

Unless someone has hijacked the meaning of the term, "damping"
quite unambiguously and precisely to the action by which energy is
removed from a system and does not return. In the case of loudspeakers,
there are three sources of such action (the permanent removal of
energy from a resonant system):

1. Electrical: motional or electrical kinetic energy is transformed
into heat by the electrically resistive elements in the circuit.
The single most significant such element is the DC resistance of
the voice coil: most of the energy will be converted by that DC
resistance into heat and removed from the system.

Changing the total loop resistance from, say, 6 ohms, connected
to an amplifier with infinite "damping factor" to, say, 6.3 ohms,
connected to an amplifier with a "damping factor" of 20, guess
what, the change in electrical damping is a STAGGERING ... 5%.

2. Mechanical, principally the frictional losses in the surround and
spider. These frictional losses are less significant than the
electrical. Typically, the mechanical damping is anywhere from
6 to 10 times less than the electrical damping.

3. Acoustical: this is the energy carried away by the sound the speaker
is making and, for the vast majority of direct-radiator speaker, this
damping comprises the tiniest part of the total dissapitive losses.