History on ohm A's and F's.

MAPMAN:

Unicorn will be able to produce over 100dB, especially with the carbon DDD option. I'm intending to get a pair for myself early next year. It's a very interesting design, unique non-horn horn loading utilizing coincident internal ports for tuning at various frequencies, etc.

Have you seen the web brochure?

http://www.german-physiks.com/images/stories/download/brochures/web/unicorn_mkII_web.pdf

John Strohbeen deserves tons of credit ... he managed to alter the design of the loudspeaker in such a way as to make it reliable ... damn near bulletproof. Furthermore, he managed to make a very enjoyable loudspeaker that has extremely compelling performance. When I was a teen these were being sold at a store in the mall and I was dumbfounded by how much different they sounded than any other HiFi I had ever encountered until then. They left a very deep impression.

I'll say, as well, that Ohm doesn't get as much attention as they deserve. I wish I saw some mainstream reviews of the stuff, as I think their speakers offer a lot for the money.

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.

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.

UNSOUND:

I don't mean to take credit away from Lincoln Walsh ... he refined the bending-wave concept into an omni design. He also managed to create a very wide-bandwidth concept. It remained a concept, commercialized by someone else (Gersten) who invented the voice coil without which it would nto have been possible. By all rights the driver should be referred to as the Walsh/Gersten driver because of that fact.

Next: The Peter Dicks driver parts ways with the Ohm driver in several ways. First of all, it was modeled more accurately. While Walsh was a genius (and so was DaVinci), he was unable to accurately model the concept in a way that would make it reliable. Dicks was able to do that. It is hardly "slanted" to say that - them's the facts.

I'm curious as to why you would take it so personally that someone might challenge the "genius" of Walsh? And it's not even a challenge, per se, but rather an assessment of the facts as regards the differences between the Walsh/Gersten driver and the DDD? Why so touchy?

The Walsh/Gersten driver resulted in failure. There are very few remaining working models in the field that have not been refurbished/repaired at least once in their lifetimes, and the design was abandoned by the company because it seems to have been a guaranteed liability. Their terrible inefficiency required tremendous power just to wake the driver up, and a little bit more power melted the voice coils.

Still - it remains one of the most interesting and well-regarded drivers in the history of the industry, and credit should be given where it is due to Lincoln Walsh for having conceived of the idea. You are 100% correct to say that he was not to blame for the failure rates as he was deceased before it was ever commercialized. Had he lived, he may have been able to figure out the answers to the problems. As it stands, it was Gersten who is both to be given credit for and blame for the commercial result of the driver.

MAPMAN: You're right to assume that as the frequencies get lower and wavelengths get longer the drivers behave more pistonically. You're also right to say that the Ohm F's and A's (as well as the GP Unicrns) are the only such drivers to have behaved full range. As a result, the Ohm drivers failed often because their voice coil was called on to move the entire mass of that massive driver cone ... and the power required to make the driver "wake up" and play at decent levels was just about enough to kill the VC's.

To this day the most engineering experience with this kind of driver comes from Peter Dicks and German Physiks. Together they have logged almost 20 continuous years of R&D into this driver with access to very advanced computer modeling along the way.

It is fair to say that Lincoln Walsh was the "father" of this kind of driver. I've read the patent he filed in 1964 and it reveals to me a prodigious intellect. It is also fair to say that Peter Dicks and German Physiks made this style of driver reliable, predictable, and much more efficient.

I'm sorry, Unsound, if this somehow ruffles your feathers. I didn't mean to offend you. In fact ... I didn't think it *could* offend you.

Dale,

I would absolutely love to hear a set of your speakers. I think that the promise of the Walsh concept has not yet been 100% fulfilled, but I remain a big fan of the concept (which is why I became the importer for German Physiks).

Where are you located?

Hi Dale,

Thanks for the invite. I'd like to come for a visit after the frost! ;-)

Chris