History on ohm A's and F's.

Mapman, I could be wrong but, I believe you are mistaken on every count.

On all counts?

Maybe.

Ohm A and F: To my knowledge: (I'll have to ask Holger M. of GP, as he has direct knowledge of this) -

Ohm A/F drivers had their VC's hard-fixed to the cone, essentially able to erupt bendingwaves at high frequencies but, as the frequencies became larger, were responsible for moving the entire inertia of the cone.

The DDD does not have the VC hard fixed to the base of the cone, but rather - as I mentioned earlier - acts as a striker through a particular elastomeric glue to erupt bending waves in the surface of the titanium foil. It does have a pistonic mode, but that mode is not reached in any of the speakers except the Unicorn (as I recall) because it is able to remain a bendingwave driver throughout it's general operating range.

The original Walsh concept was just that - a concept. It took Gersten's unique voice-coil to make the concept a practical (used loosely) reality. Walsh died before the application was fully commercialized. Once the concept had been commercialized, the release was rife with failures. Theory and practice parted ways, as the business seemed to be engaged in as many repairs as they were engaged in new sales. At some point, I suspect, the repairs must have overtaken sales and it was time for a change.

Ohm's John Strohbeen created a hybrid concept, marrying a tweeter to an inverted dynamic mid-bass driver, and that design has been the "Ohm" design for a long time.

German Physiks' DDD driver was the invention of Peter Dicks, who - for the first time - applied the mathematics required to successfully model this style of bending wave driver. In so doing, he essentially invented the concept as a practical matter - converging theory and practice. Several more years in development at German Physiks had the DDD ready for prime time. Since 1992 the driver has been successfully commercialized.

Curiously - to say that the DDD is a variation of a Walsh driver (as described in LW's patent), in a fashion, to say that the Blackhawk helicopter is a variation of a drawing of a flying machine by DaVinci. While the DaVinci is certainly elegant and inspired, the GP actually works, and works with predictable precision and reliability.

The operating principle of the DDD driver, as used in the German Physiks HRS 120 (10-inch acoustic suspension woofer below 240Hz):

"The lower frequency end of its operating range can be described with Thiele/Small resonant parameters, while in the next frequency band up to the coincidence frequency 'it works like a pistonic driver'. Next, there’s an overlapping band where pistonic movement is 'progressively replaced by bending waves until all the radiation is generated purely by bending movement in the cone'."

Hi-Fi World review here.

Csommovigo,

Sounds like a reasonable accounting of the similarities and differences to me. Thanks.

IS it accurate to say that the different designs all operate on similar principles despite the fact that the implementation of each is significantly different, for better or for worse?