"Rob" wrote in message

Phil Allison wrote:
"Arny Krueger"

The cone works against a relatively large mass - the
speaker and its enclosure.


** The mass ratio of a whole speaker box to the woofer
cone is around 500: 1, or more.

The conservation of momentum principle ( Newton's "every action causes an
equal and opposite re-action" )
requires that the momentum of the moving cone and whole
box remain equal and opposite. So, the box moves about
0.2% of the cone's movement in the opposite direction. Typical woofers
move at most 6mm forward and back when
producing the lowest bass frequencies.

The box, in compliance with Newton, then moves 12 um
back and forward. 12 um = 0.5 thou = one quarter the thickness of a
page in the phone book.
Why bother with spikes and cones at all?
Because it sounds better.
Only in sighted evaluations.


** Of course.


IME it doesn't always work like that. My Dynaudio 1.1s
sit on some stands with a smallish top plate. After an
hour of fairly spirited listening, they'd moved about 4cm
forward. I'd usually use blutack for that reason - it's
all in the movement of air.

I see no necessary conflict between Phil's estmate and your anecdote. The
intresting thing is that there is that much asymmetry in the sticktion of
the speaker interface with the stands. Blutack seems like a worthy
solution, particularly if you use one the similar generic products sold at
office supply stores.