History on ohm A's and F's.

Pardon my intrusion, but as the North American distributor for German Physiks I hope I can add some information to the discussion:

by the way - to my knowledge, Huff has not had access to the German Physiks DDD driver for quite some time. Holger Mueller (owner of German Physiks) said that he had stopped supplying the driver to OEMs some time ago.

Also - with regard to the technology in the German Physiks DDD driver - it is not a "truncated" Walsh driver as one suggested, but rather a bending wave driver (the Walsh was a purely pistonic driver, which was at the core of its efficiency issues).

The DDD is actually made from microns-thin titanium foil or carbon fiber, and the voice coil is not fixed hard to the cone but rather acts as a striker might act on a bell, causing predictable distortions in the surface of the foil ... which in turn project the sound into the air.

It is true that the DDD does not perform into low frequencies the same way the original Ohm driver did. Then again, it also doesn't require megawatt amplifiers to come alive, not will it melt down the moment it starts getting enjoyable.

"(the Walsh was a purely pistonic driver, which was at the core of its efficency issues)."
???

I think saying the Walsh speaks including As and Fs are pistonic is an accurate statement.

Regarding efficiency, though I would not doubt the DDD driver is more efficient than the original Walsh A or F drivers from 30 years ago, I think comparing a full range driver like those on the Ohm A and F to a limited range driver that does not cover the low end like the DDD is an apples and oranges comparison.

I do believe that unlike the current Ohms, the original Ohm Walsh's were bending wave drivers, and the German Physiks DDD is just an update of the original Walsh concept. The "inefficiency" of the original Walsh drivers might be due to other factors.

I think the Ohms were both bending wave and pistonic using a voice coil and foam surround.

Sounds like the drive mechanism for the DDD is different as described by Csommovigo as like "striking a bell", but honestly the exact difference is not clear to me.