| Peter Dicks and DDD Wave Converter - Click HERE for Original Thread |
| 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? |
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| janneman |
| quote: | 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 |
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| amsci99 |
| quote: | 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. |
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| 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. |
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| 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. |
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| janneman |
| quote: | 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 |
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| el`Ol |
| Every sudden change of the acoustic impedance will cause a reflection. |
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| janneman |
| quote: | 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 |
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| 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 |
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| janneman |
| quote: | 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 |
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| el`Ol |
| quote: | Originally posted by janneman
Ordering special-treatment titanium sheets at single sample quantities is probably more expensive than pure gold.
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How true, how true.
http://www.memory-metalle.de/ |
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| janneman |
I understand that Mr. Dicks is in the process of updating the (technical) information about the DDD drivers on the German Physics website. As soon as that is done I'll give you guys a heads-up here.
Jan Didden |
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| lumanauw |
Has anybody heard German Physics loudspeaker? I need an input on this.
How is the sound, say, compared to Wilson WAMM? |
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| janneman |
David,
I can only compare the DDD's (in a complete system) to the Wilsons I heard in Bandung; I don't remember if that were WAMMs.
No misunderstanding: the Wilsons sounded very, very good. That whole system sounded very lifelike and was surely one of the best I ever heard.
But I would think that the DDD's are probably just a bit more refined, maybe less overwhelming and therefore more convinving. These were DDD's with titanium foil cones; I haven't heard the newest ones with carbon cones which presumably might even be better.
Just my 2ct worth.
Jan Didden |
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| lumanauw |
Hi, Janneman,
Thanks :D |
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| EC8010 |
| It's quite easy to knock up a distributed mode loudspeaker. I made a pair out of modelling card and two nasty little 65mm drivers. Total cost was < £15 and the most expensive part was the card (about £10). Here's a measured response: |
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| janneman |
| quote: | Originally posted by EC8010
It's quite easy to knock up a distributed mode loudspeaker. I made a pair out of modelling card and two nasty little 65mm drivers. Total cost was < £15 and the most expensive part was the card (about £10). Here's a measured response: |
I take it that you show this curve as a deterrent ;) ?
Jan Didden |
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| moray james |
| ues a standard voice coil and magnet assembly (best to eliminate the spider though). Connect the top of the voice coil to a tensioned plastic diaphragm install some form of dust cap. Now when you pulse the diaphragm a wave front is set in motion forward from the dust cap while at the same time the voice coil imparts a annular wave form which spreads out across the plastic diaphragm. The leading edges of theses two acoustical events are linked and in sink with each other. The end result is a spherical (reasonable fax) wavefront generated from a flat plastic diaphragm. It is the old ripple in a pond. Works like a charm if you juggle it properly. If any one wants to complain that it could not can not will not work because of so many reasons then explain how that german blathaller jig is selling for silly money. Give it a try before you say it wont because it will. |
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| janneman |
| quote: | Originally posted by moray james
ues a standard voice coil and magnet assembly (best to eliminate the spider though). Connect the top of the voice coil to a tensioned plastic diaphragm install some form of dust cap. Now when you pulse the diaphragm a wave front is set in motion forward from the dust cap while at the same time the voice coil imparts a annular wave form which spreads out across the plastic diaphragm. The leading edges of theses two acoustical events are linked and in sink with each other. The end result is a spherical (reasonable fax) wavefront generated from a flat plastic diaphragm. It is the old ripple in a pond. Works like a charm if you juggle it properly. If any one wants to complain that it could not can not will not work because of so many reasons then explain how that german blathaller jig is selling for silly money. Give it a try before you say it wont because it will. |
Moray,
Does the Manger work in this way?
Jan Didden |
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| EC8010 |
| quote: | Originally posted by janneman
I take it that you show this curve as a deterrent ;) ? |
Not really. I've measured commercial loudspeakers that were a good deal worse. |
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| moray james |
| to the best of my recolection the Manger is a bending wave device. I do know that Manger approached Highwood Audio because our patent was in his way at the time. My old partner Paul once discribed this as a hornless horn loaded speaker. He was referring to the traveling wave in the diaphragm acting akin to a wave guide. It is a very interesting idea but it takes a lot of work to make the pony do its trick. you can look at US 4, 924, 504. |
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| c2cthomas |
Ta Moray -
I'm taking a stab at guessing that the reason for getting rid of the spider is a) reflections b) bites c) cobwebs! :D :D :D |
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| planet10 |
| quote: | Originally posted by moray james
ues a standard voice coil and magnet assembly (best to eliminate the spider though). Connect the top of the voice coil to a tensioned plastic diaphragm install some form of dust cap. Now when you pulse the diaphragm a wave front is set in motion forward from the dust cap while at the same time the voice coil imparts a annular wave form which spreads out across the plastic diaphragm. The leading edges of theses two acoustical events are linked and in sink with each other. The end result is a spherical (reasonable fax) wavefront generated from a flat plastic diaphragm. It is the old ripple in a pond. Works like a charm if you juggle it properly. If any one wants to complain that it could not can not will not work because of so many reasons then explain how that german blathaller jig is selling for silly money. Give it a try before you say it wont because it will. |
Moray,
Isn't this essentially the same tech you guys developed for the flat-panel speaker?
dave |
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| moray james |
| just another way of doing much the same thing a walsh cone does. |
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| janneman |
Hi,
Just wanted to let you know that Peter Dicks has updated the technical info on his driver recently. It's now more tech, less marketing blurb.
The pertinent page on the German Physiks website starts here:
http://www.german-physiks.com/techn...ddd-driver.html
Jan Didden |
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| oshifis |
| Some 25 years ago I read an university thesis on a travelling wave loudspeaker. It was composed of a flat honeycomb structure excited by voice coils at the left and right edges (in stereo). I was said the acoustic waves were travelling in lateral direction across the length of the radiator (left and right channel in opposite direction), and radiated from the whole surface at a defined angle (not perpendicular). There was some dampening at the edges to absorb the waves at the end of their travel. Does the Wave Converter work on a similar principle? |
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| janneman |
As I said, there is now much more info on the website. Note also that the DDD actually has 4 regions of fundamentally different operation, depending on the freq range of the signal. It is better explained there then I can repeat here.
Jan Didden |
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