"Jerry Avins" schrieb im Newsbeitrag
...
raymund hofmann wrote:

I am looking for a "moving coil exciter" suitable for attaching to
some
surface like a window glass. I want to turn a window glass into a
speaker. I don't want to achieve high sound pressures, but
prefereably
be able to go down to ~35 Hz (at sound pressures quite low).
I guess signal processing and driving the exiter to it's limits is
necessary to achieve linear response down to 35 Hz.
I already have found the "soundbug" marketed as computer accessory.
But
this is not what i am looking for as it is active and uses
batteries. I
rather look for a passive solution which may be like a "speaker
without
membrane".
Or may i be able to build such a thing on my own by buying some
parts
used in a speaker ?
Where could i look for seperate speaker parts like the magnet &
coil. I
could then try to attach the coil to some suction cup for attaching
it
to a window.

Raymund Hofmann

Have you seen such an exciter? What holds it relatively stationary as
the class moves under its influence? Inertia? What would you expect
its
mass to be? Do you expect the frequency response depend on the size,
shape, and thickness of the glass? This is intriguing.

I have seen such a thing mentioned / described in:

http://www.tannoyna.com/commercial/pdf/wp_nxt.pdf

But I wonder if i may be able to buy some ready made moving coil exiters
somewhere.

The mass should be high enough to result in the needed forces to the
window glass without driving the voice coil too hard and thus getting
too non-linear.
Concerning the Frequency response I would have to do compensation anyway
to achieve my goal.
So the thing is mainly that it stays linear enough with the applied
power for the application.

Raymund Hofmann