[David Grant]

My understanding (of the sales pitch/marketing ?) of the function of cones
or spikes was that they were supposed to act as a 'physical diode'..in
other words to allow unwanted vibrations and micro-motion to transfer from
the speaker cabinet into the thick end of the cone and then down through
its point to a massy, inert body below it (floor, shelf, concrete slab
etc) which would then absorb the vibes and in theory refuse to allow them
to be reflected back up the spike/cone again ? I don't know how complete
this diode principle was meant to be, in terms of allowing one way
transmission of kinetic energy only ? Wouldn't that depend on a gradation
of absorptive materials on the downwards path so that 'reflections' of
energy wouldn't travel back up the cone again ...? So if the cone point
terminated in a full sandbox, for example, that would presumably act as an
energy-sink. Dunno, that's my shaky (ha !) understanding of the "theory"
anyway.
RT


I studied transmission lines from an electrical engineering standpoint a few
years ago and I expect this represents the mechanical equivalent. It should
be possible to minimize vibration reflections at the termination via
impedance matching (where impedance in this case is a complex value based on
mass, spring, damping).

The diode analogy sounds iffy. The direction of elecron flow can be
controlled using charges but a vibration carries no polarity. I don't
believe an atom of matter has any means with which to determine whether a
vibration came from direction x or direction -x. It would have to
communicate with adjacent members to determine the direction of propogation,
and then somehow it would have to absorb that energy or transmit it
depending on the case. That doesn't sound like a natural property of matter.