Hi lowmass and welcome back
You have put so many topics on the table that I find it difficult to comment in order. The first thing I have noticed with satisfaction is that the results of your experiences regarding the topics I have covered in previous posts (i.e. that they do not significantly affect the distortion) coincide with my results. The concept that similar experiences conducted by different people and by different means must give similar results is fundamental to establishing the correctness of the results. I had put aside the turbulence phenomenon both because I had read in several discussions that it only annoys when the width of the gaps is medium, i.e. between a few tenths and a couple of mm (and in the tests I used a 4 mm gap) and because I think to the ribbons as full range and therefore necessarily with lateral suspension like those of the ribbons in post # 2 and those of the Russian company you mentioned. It is my opinion that you cannot hope to reproduce the low frequencies (below a few hundred Hz) with a ribbon with gaps that let the front and rear sound fields mix. I have not noticed in my experiences that lateral suspensions involve Hash in the higher frequencies (I would say that in that field they do not alter the response at all), nor a worsening in the impulse response, unless there is something wrong with the realization.
The graphics you posted are outstanding, so I assume you have truly found a way to drastically reduce the distortion of a true ribbon.
About what you noticed
"although the distortion was significantly reduced, I did not hear a significant improvement in sound quality at“ normal ”listening volumes. I will call this crusing at around 90 db or so. At higher volumes it was noticeably better BUT is certainly wasn't staggering ".
In my opinion it can be due to 2 factors: The first is that the distortion in the ribbons increases by about 12 dB / octave every 6 dB of increase in the SPL, The second is that it is distortions below or near the audibility limit, so it is difficult to perceive them.
Good luck for your patent, I augur it can make you a lot of money. I will keep my curiosity in check until you are ready to share your discovery.
I wonder why you don't also deal with full range drivers, because you surely know that you can make a tweeter perfect as much as you want but then you have to make several compromises when you pair it with a mid or a woofer.
I fully agree with you on planar and folded diaphragm drivers.
Happy Holidays to you too
You have put so many topics on the table that I find it difficult to comment in order. The first thing I have noticed with satisfaction is that the results of your experiences regarding the topics I have covered in previous posts (i.e. that they do not significantly affect the distortion) coincide with my results. The concept that similar experiences conducted by different people and by different means must give similar results is fundamental to establishing the correctness of the results. I had put aside the turbulence phenomenon both because I had read in several discussions that it only annoys when the width of the gaps is medium, i.e. between a few tenths and a couple of mm (and in the tests I used a 4 mm gap) and because I think to the ribbons as full range and therefore necessarily with lateral suspension like those of the ribbons in post # 2 and those of the Russian company you mentioned. It is my opinion that you cannot hope to reproduce the low frequencies (below a few hundred Hz) with a ribbon with gaps that let the front and rear sound fields mix. I have not noticed in my experiences that lateral suspensions involve Hash in the higher frequencies (I would say that in that field they do not alter the response at all), nor a worsening in the impulse response, unless there is something wrong with the realization.
The graphics you posted are outstanding, so I assume you have truly found a way to drastically reduce the distortion of a true ribbon.
About what you noticed
"although the distortion was significantly reduced, I did not hear a significant improvement in sound quality at“ normal ”listening volumes. I will call this crusing at around 90 db or so. At higher volumes it was noticeably better BUT is certainly wasn't staggering ".
In my opinion it can be due to 2 factors: The first is that the distortion in the ribbons increases by about 12 dB / octave every 6 dB of increase in the SPL, The second is that it is distortions below or near the audibility limit, so it is difficult to perceive them.
Good luck for your patent, I augur it can make you a lot of money. I will keep my curiosity in check until you are ready to share your discovery.
I wonder why you don't also deal with full range drivers, because you surely know that you can make a tweeter perfect as much as you want but then you have to make several compromises when you pair it with a mid or a woofer.
I fully agree with you on planar and folded diaphragm drivers.
Happy Holidays to you too
Basically If you are using a ribbon with a large enough surface area, then the turbulence at the gap can be usefully reduced simply because the ribbon doesnt have to move much to make the desiered SPL.
Also if you make the gaps rather large you can reduce the turbulence somewhat and the distortion as well.
However as U mention the bigger the gaps the more problem with lower freq sensativity, AND this becomes more and more of a problem with the more practical smaller surface area ribbons.
As for the side suspension hash. In all my protos that used a similar suspension I see extra hash that takes longer to decay than I see in a free swinging ribbon. Cant remember but I think its mostly in the 2-5 khz range somewhere. Based on many tests of similar structures I see this consistantly. However that doesnt mean I have proven this method to always be a problem. Its often all in the exacution.
I see you are working with quite large ribbons. Its possible on a very large ribbon that the movments are so small in the 2-5k range that the side suspension is simply not excited much. Also size and shape are everything and a small, light, poorly damped half roll of polyester film or Kapton film will form a riggid beam along the ribbons length. I suspect this is singing a bit at certain freqs but I admit I am not absolutly sure. I really only know I could always get a quieter background with no suspension AND avoiding rigidity along the length that wasnt well damped.
I did do years of effort on "full range ribbon". In fact thats where I stated this madness ha. From curved panel planers to large free swinging tru ribbons. In the end I decided that the tru free swinging ribbon about 2 inces wide and at least 5 feet tall was the most convincing BUT compermises in dispersion always bothered me and the poor sensativity and near zero practicality were deal breakers except for my own listening room.
In the end I decided that what we really need is a sphearical shapped driver and I have been working on that one on and off but at a low pace as I have bigger responsabilities going farward. I believe it will be a planer when / If its ever realised.
As for the latest patent on the small ribbon design. The patent is written BUT I have no intension of filing it. I do not see this as a solid money making thing as the cheap domes are getting quite good AND a good ribbon will likley always be a much more expensive thing to build. I decided to hold onto the tech and the patent eather as somthing for me to do in retierment ( 5 years away) as a small income on side, OR simply sell the tech and patent off to someone down the road.
Also if you make the gaps rather large you can reduce the turbulence somewhat and the distortion as well.
However as U mention the bigger the gaps the more problem with lower freq sensativity, AND this becomes more and more of a problem with the more practical smaller surface area ribbons.
As for the side suspension hash. In all my protos that used a similar suspension I see extra hash that takes longer to decay than I see in a free swinging ribbon. Cant remember but I think its mostly in the 2-5 khz range somewhere. Based on many tests of similar structures I see this consistantly. However that doesnt mean I have proven this method to always be a problem. Its often all in the exacution.
I see you are working with quite large ribbons. Its possible on a very large ribbon that the movments are so small in the 2-5k range that the side suspension is simply not excited much. Also size and shape are everything and a small, light, poorly damped half roll of polyester film or Kapton film will form a riggid beam along the ribbons length. I suspect this is singing a bit at certain freqs but I admit I am not absolutly sure. I really only know I could always get a quieter background with no suspension AND avoiding rigidity along the length that wasnt well damped.
I did do years of effort on "full range ribbon". In fact thats where I stated this madness ha. From curved panel planers to large free swinging tru ribbons. In the end I decided that the tru free swinging ribbon about 2 inces wide and at least 5 feet tall was the most convincing BUT compermises in dispersion always bothered me and the poor sensativity and near zero practicality were deal breakers except for my own listening room.
In the end I decided that what we really need is a sphearical shapped driver and I have been working on that one on and off but at a low pace as I have bigger responsabilities going farward. I believe it will be a planer when / If its ever realised.
As for the latest patent on the small ribbon design. The patent is written BUT I have no intension of filing it. I do not see this as a solid money making thing as the cheap domes are getting quite good AND a good ribbon will likley always be a much more expensive thing to build. I decided to hold onto the tech and the patent eather as somthing for me to do in retierment ( 5 years away) as a small income on side, OR simply sell the tech and patent off to someone down the road.
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Hi Lowmass
I agree with everything you wrote. I read that you used polyester and kapton films for the side suspensions. I haven't even tried them because I suspected they would give the inconveniences you mentioned. Instead I first used very light paper impregnated with various polymers, but then I switched to polyester fabric and then there was the turning point: No longitudinal stiffness, great compliance and no singing at any frequency. There is still a lot to experiment both on the shape, because the half-round tends to have an asymmetrical elasticity, and on the material because with thin aluminum ribbon you need very thin and very light fabrics, but I have been retired for many years, I have all the time I want and a full range ribbon seems to me a goal worth pursuing. The spherical-shaped driver also attracts me a lot, and I often think about it, but I still don't have the right idea.
As for patents, I tell you my experience: I have always had problems and even scams by patenting and then trying to exploit the patent. But I don't want to discourage you, because maybe in the USA things don't go like in Italy. However in the end I adopted the last option you wrote: without patenting (because as soon as you have patented in one way or another someone steals the idea from you), I built a prototype and I sold that together with the idea to the highest bidder , cash. Happy ending to the story, and then I happily moved on to work on another idea.
I agree with everything you wrote. I read that you used polyester and kapton films for the side suspensions. I haven't even tried them because I suspected they would give the inconveniences you mentioned. Instead I first used very light paper impregnated with various polymers, but then I switched to polyester fabric and then there was the turning point: No longitudinal stiffness, great compliance and no singing at any frequency. There is still a lot to experiment both on the shape, because the half-round tends to have an asymmetrical elasticity, and on the material because with thin aluminum ribbon you need very thin and very light fabrics, but I have been retired for many years, I have all the time I want and a full range ribbon seems to me a goal worth pursuing. The spherical-shaped driver also attracts me a lot, and I often think about it, but I still don't have the right idea.
As for patents, I tell you my experience: I have always had problems and even scams by patenting and then trying to exploit the patent. But I don't want to discourage you, because maybe in the USA things don't go like in Italy. However in the end I adopted the last option you wrote: without patenting (because as soon as you have patented in one way or another someone steals the idea from you), I built a prototype and I sold that together with the idea to the highest bidder , cash. Happy ending to the story, and then I happily moved on to work on another idea.
yep most patents not worth much. You have to have found somthing trully unique and worth somthing, developed the best way to do it, and thats just the start, now you have the hard work of pitching it to the masses. Good luck with all that Ha! My first ribbon patent was filed more for resume fodder. In the end I wrote another patent for the new design while the details were hot in my mind but I likley will not do anything but sell it. I have far more important things to do before I leave this world 
.
I too tryed doped fabric for surrounds, even putting multiple slits to relieve lengthwise riggidity. I cant remember wher I got it but a light polyester fabric doped with urithane was good. I molded the polyester fabric around some dowel and placed in oven at around 300 degrees for about 20 seconds. Pull it out an you have a formed half roll. From there brushed on various "dopes" thinned out. Fabric is as u say best. Very quiet. I ended up going with the free swinging ribbon design as it was easyer to manufacture AND its reliability was now on par with domes.
US9668057B1 - Ribbon transducer
- Google Patents
.I too tryed doped fabric for surrounds, even putting multiple slits to relieve lengthwise riggidity. I cant remember wher I got it but a light polyester fabric doped with urithane was good. I molded the polyester fabric around some dowel and placed in oven at around 300 degrees for about 20 seconds. Pull it out an you have a formed half roll. From there brushed on various "dopes" thinned out. Fabric is as u say best. Very quiet. I ended up going with the free swinging ribbon design as it was easyer to manufacture AND its reliability was now on par with domes.
US9668057B1 - Ribbon transducer
- Google Patents
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