Gobel and the Bending Wave

Are AMTs/folded ribbon drivers bending wave?

As I define it, the bending wave is defined by a membrane where one end or point is excited, causing a wave to form on the membrane which tavels to the extremities.


A cone, driven pistonically, endeavors to have the same relative motion at all points.

Ribbons, AMT's and ESL's are excited across their length simultaneously.  There's no wave which travels from point A to point B.

Quads however, as I understand them, are in fact bending wave transducers.  They are excited at the center, and the wave then travels to the outer edges.

Hmm well bending wave Walsh style drivers are essentially specially designed cones that operate pistonically just like traditional dynamic drivers.


"
Bending wave loudspeakers

Bending wave transducers use a diaphragm that is intentionally flexible. The rigidity of the material increases from the center to the outside. Short wavelengths radiate primarily from the inner area, while longer waves reach the edge of the speaker. To prevent reflections from the outside back into the center, long waves are absorbed by a surrounding damper. Such transducers can cover a wide frequency range (80 Hz to 35,000 Hz) and have been promoted as being close to an ideal point sound source.[62] This uncommon approach is being taken by only a very few manufacturers, in very different arrangements.

The Ohm Walsh loudspeakers use a unique driver designed by Lincoln Walsh, who had been a radar development engineer in WWII. He became interested in audio equipment design and his last project was a unique, one-way speaker using a single driver. The cone faced down into a sealed, airtight enclosure. Rather than move back-and-forth as conventional speakers do, the cone rippled and created sound in a manner known in RF electronics as a "transmission line". The new speaker created a cylindrical sound field. Lincoln Walsh died before his speaker was released to the public. The Ohm Acoustics firm has produced several loudspeaker models using the Walsh driver design since then. German Physiks, an audio equipment firm in Germany, also produces speakers using this approach.

The German firm, Manger, has designed and produced a bending wave driver that at first glance appears conventional. In fact, the round panel attached to the voice coil bends in a carefully controlled way to produce full range sound.[63] Josef W. Manger was awarded with the "Diesel Medal" for extraordinary developments and inventions by the German institute of inventions."

@mapman

You should read your own posting. Your quoted text directly contradicts your first sentence.

No contradiction. The driver modulation is pistonic with sound produced via wave bending as described. The current Walsh model speakers produce lower frequencies pistonically and the higher frequencies through the midrange via wave bending.

Yeah, if you say so.