Gobel and the Bending Wave

Sorry, AMT is not bending wave, Atmasphere. It's motion is pistonic, although at an angle. :)

IMHO, to be a bending wave, the transducer must be excited at one end, and have the sound wave emit off the surface as the wave travels from one end to the other, or from a central point to the edge.

AMT's are driven across their entire length at the same time. There is no start and end to the wave across its surface.

Right, and I see no evidence that this 8" driver is being used in any other way than pistonic, especially given crossover points.

Mind you, these are very good parts and the speaker may be amazing. I'm just scratching my head over what appears to be shamelessly branding a standard 8" cone with "bending wave."

The model shown here ( Epoque Aeon ):

https://www.youtube.com/watch?v=Ipjahbc6QRE

looks like the seemingly hidden driver at the top could use the advertised bending wave principle similar to Manger speaker drivers. Pistonic motion would be radial with sound emitted at an angle to that.

The original and somewhat well known "bending wave" configuration that has been around for some time as mentioned is of course that of the Lincoln Walsh-style transmission line drivers where driver is mounted vertically with vertical pistonic motion. Original OHM A’s and F’s from years back did this fairly full range with a single physical driver, newer OHM Walsh model speakers do it similarly but just for the key mid frequencies using much more conventional (and robust) drivers. German Physiks DDD drivers do it for the higher frequencies. Dale Harder’s Exotic Speakers line (very hard to find) take the original OHM Walsh full range design and refine it with more modern technology.

BTW My understanding is that many otherwise conventional dynamic (pistonic) drivers can also function as bending wave drivers for certain frequencies, most perhaps just not very well unless designed to do so. They also do have to be mounted vertically though so the sound emanating at an angle from the rear of the cone is primarily what reaches your ears.

Are AMTs/folded ribbon drivers bending wave? I’ve never thought them to be as I understand it, though perhaps more unconventional in operation than most high frequency drivers, but in a different way. Same true of MBL speakers in general, unique configuration but technically not "bending wave" TTBOMK.

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.