Acoustic magnetic generator.

[verpies]

Note that some of the piezo power is being "shorted" through the clamp system, and it becomes another impedance discontinuity causing reflections. 

Indeed that is a concern.  It can be mitigated by placing the clamps at displacement nodes because the rods are not moving at these nodes.

Re. Damping:

How long does the ferrite rod ring after being struck with a hammer while being suspended in the air by a thin thread in the middle?
VS.
How long does it ring in the "clamp system" ?

Have you seen clips of those "vibration tables" on YouTube?  Sometimes they just put sand on the table and as the frequency is swept there are multiple "resonance points" where the sand grains gather at the vibratory nodes on the square vibrating apparatus.  You see all of these amazing patterns. 
Other people put "goop" on the tables and at various frequencies it looks like the goop is "alive" and doing various things.  "The Blob"

Visualizing standing waves in the rod would be very useful.  The difference is that vibrations of those cymatic Chladni tables, you mentioned, are mostly transverse while vibrations in these ferrite rods are predominantly longitudinal and such vibrations don't affect the sand above the surface much.

Once, I was successful in visualizing longitudinal vibrations  by grinding a small groove in the surface to hold sieved sand in it.
When the rod was sampled below the surface and the friction was maximized by the groove, grains of sand became accelerated horizontally and they bumped into each other ...forming patterns.

I realize that the waves are primarily going to be longitudinal waves, but there will still be transverse waves generated also.  So a microphone sliding down the rod won't be able to hear the longitudinal waves, but it would be able to hear the transverse waves.

In this method of standing wave visualization the microphone needs to be continuously scanned along the length of the rod, but also:

It is not guaranteed that transverse waves would be spatially correlated with longitudinal waves in the rod. 
Also, Itsu has significant electric capacitive coupling issues in his system, that would interfere with the weak signal from a nearby microphone  (and a ceramic phonograph cartridge, too).
Finally, any jagginess of the microphone's frequency response would falsify the perceived amplitude of the received sound which is the major determinant of node positions in this method.

For your big magnets lying flat, are they polarized "up-down?"  I noticed that there are pole designations on those big flat surfaces.  I thought the goal was to make a magnetic flux loop?

Initially I was concerned about that too, but in the end I was not expecting Itsu to make that mistake.
Also, I have another concern involving the integral of sine µ, which is zero for integer number of cycles.

[itsu]

Great info once again guys,  thanks a lot.

Its thru that those ceramic magnets are polarized "up-down", therfor the N/Z notations on them, well spotted.
But i found them to pretty solidly attract together as they where in my first setup, a screwdriver was attracted very well
to the both sides of the rods so there was flux going around.

But if it was enough i doubt it now.

I have rearrange them now with an iron bar inbetween as flux guide, and now the attraction is much better, even so
the both rods attach them selve to the piezo firmly without any clamps used.

Initial tests show many more pickups with the bare FG only, also around 14KHz.

Further tests / video will follow.

Regards Itsu

[MileHigh]

Itsu:

Looking forward to your clips.  One quick thought is that even with the increased magnetic attraction across the piezo, you still need some sort of "juice."  A very thin layer of Vaseline for the two contact surfaces should work quite well and it may already be in your bathroom medicine cabinet!

MileHigh

[itsu]

Ok, here the once again changed setup.
The magnetic flux is now much stronger, but it does not equate to stronger signals in the pickup coil.
A led across this pickup coil never lights, only all the way up in the coils resonant state (290KHz)
I do have some minor fluctuations now in the lower frequency range (12-15KHz) which i will try to enhance.

Video here:  https://www.youtube.com/watch?v=mNnnaFjqZyc&feature=youtu.be

Regards Itsu

[synchro1]

@Itsu,


Is that a bridge rectifier between the pickup coil and the LED?