Peter Dicks and DDD Wave Converter

[amsci99]

Whilst information on the Walsh driver can be easily found, I don't seem to find anything on Peter Dicks and his famed DDD Wave Converter as used on the German Physiks range. Tried AES but appears there is no paper on this. I believe that it is possible to convert a conventional driver by disassembling one and adding the directional cones and ancillaries on convert one to a DDD Wave Converter but need to know the physics to get the design to work.

Any thoughts on this?

[janneman]

Originally posted by amsci99
Whilst information on the Walsh driver can be easily found, I don't seem to find anything on Peter Dick and his famed DDD Wave Converter as used on the German Physiks range. Tried AES but appears there is no paper on this. I believe that it is possible to convert a conventional driver by disassembling one and adding the directional cones and ancillaries on convert one to a DDD Wave Converter but need to know the physics to get the design to work.

Any thoughts on this?

I know Peter Dicks and have had some discussions on his drivers, many years ago. The DDD cone functions very much different then a conventional cone. Normally cones are designed to act as much as possible as a stiff piston. A DDD cone works, like the Walsh, by 'rippling' the wave across the cone to the surround. The cone flexes in a very defined way to do this. The material, geometry (angle) as well as the terminating surround are all quite different and I'm sure a 'conventional' cone will not function as a DDD.

Jan Didden

[amsci99]

Originally posted by janneman



I know Peter Dicks and have had some discussions on his drivers, many years ago. The DDD cone functions very much different then a conventional cone. Normally cones are designed to act as much as possible as a stiff piston. A DDD cone works, like the Walsh, by 'rippling' the wave across the cone to the surround. The cone flexes in a very defined way to do this. The material, geometry (angle) as well as the terminating surround are all quite different and I'm sure a 'conventional' cone will not function as a DDD.

Jan Didden

Jan,

Thanks for the prompt reply. Actually, I was thinking of using the magnets, coil and suspension and rebuild the cone, spider and ancillaries. A whole lot of machine work but I think it would come close to Peter Dicks's DDD. Now the problem is to get some literature behind the physics of the DDD.

[amsci99]

By the way, did anyone save a copy of Peter Dicks's technical paper on the DDD bending converter which was available on the German Physik's site sometime ago? Would definitely like to take a look.

[el`Ol]

What I find strange is that they use materials with poor damping like carbon and titianium. Maybe the "math" is to reduce the reflection problems to a single peak that can be notched out.
To avoid voice coil centering problems it may be wise to slaughter spiderless DC Gold drivers, expensive, but it will make life easier. If the bending wave is dead before it reaches the bottom I see no problem with a segmented diaphragm.

[janneman]

Originally posted by el`Ol
What I find strange is that they use materials with poor damping like carbon and titianium. Maybe the "math" is to reduce the reflection problems to a single peak that can be notched out.
To avoid voice coil centering problems it may be wise to slaughter spiderless DC Gold drivers, expensive, but it will make life easier. If the bending wave is dead before it reaches the bottom I see no problem with a segmented diaphragm.

I think they don't want damping in the diaphragm. The problem they have is to absorb the travelling wave at the surround to avoid it being reflected back up.

Jan Didden

[el`Ol]

Every sudden change of the acoustic impedance will cause a reflection.

[janneman]

Originally posted by el`Ol
Every sudden change of the acoustic impedance will cause a reflection.

Indeed. That's why this is such a big issue with these drivers. It should give people pause about just whipping together any old speaker parts and expect it to work flawlessly as a Bending Wave Transducer.

Jan Didden

[planet10]

I've heard the DDD and it really is very good. A huge amount of work has gone into this driver to not just make it work but to make it work well...

dave

[janneman]

Originally posted by planet10
I've heard the DDD and it really is very good. A huge amount of work has gone into this driver to not just make it work but to make it work well...

dave

I actually worked for Peter Dicks in the early 90's, at NATO's European Headquarters in Mons, Belgium. We spend lots of hours listening at his chateau. I don't know how much money he spend on this, but it must be many 10's of thousands of Deutschmarks at that time. Ordering special-treatment titanium sheets at single sample quantities is probably more expensive than pure gold. He also had boxes full of surround prototypes, equally expensive. IIRC he was working on it for at least 10 years before the first acceptable prototypes. Then Holger Muller of Mainhattan Acoustics founded German Physics just to market the DDD's. But Peter Dicks didn't expect to break even in his lifetime. For him it was just the fascination in developing this.

Jan Didden