I finally got to record my friends open baffle dml panel.
I almost forgot to record them again 😄
We did not have much time to listen as we were chatting too much and catching up on things.
Steve.
We did not have much time to listen as we were chatting too much and catching up on things.
Steve.
Rice paper is an interesting membrane material. Biggest problem is that it absorbs water vapor and stiffness changes with ambient humidity. I know this from using it for making spring rolls - dipping it in water transforms a hard stiff membrane to a soft pliable sheet you can roll food with. Perhaps a sealer like shellac can be applied to prevent humidity absorption. But then we could something like Kapton (polyimide) which comes in various thicknesses.
You can use baking parchment paper to create the membrane. You can use a highly diluted glue in acetone, or something similar, and paste one piece over another until you achieve the desired thickness. The acetone will evaporate over time. You may notice a 3D membrane made with baking parchment paper here. In this video, you will see rice paper being used in the same manner, glued together in the same way.
Together with a flattened coil glued to such a membrane, that membrane would be practically featherweight. And, without the magnets and casing weighing down the membrane, it can vibrate freely, as seen in those videos and earlier ones. The dark honeycomb-like membrane in one of the videos is not like the honeycomb used in Tectonic Labs, but is made from paper. Additionally, the surface is treated with fine-grained marble.
That’s a great idea to glue just the coil to the membrane and have magnet external to reduce mass. Do you have an image of the completed membrane with coil glued on? Backside photo of the speaker would be helpful. Thanks.
I think the panel is a 2 or 3mm corrugated cardboard and the exciter might be a tectonic 10watt exciter.
I have asked my friend to send me the exact details when he has time.
Steve.
lekha...I really fail to see why you're seemingly obsessed with this concept. The membranes in a so called standard DML panel do not have to be "weighed down" by the magnet and casing. Simply supporting the exciter on the frame removes the magnet and casing mass from the diaphragm, and a standard coil affords better linearity and excursion than can ever be achieved by a flat coil used in the manner shown.
I'm sure you'll disagree, but I believe you're on a wild goose chase on this path, with not a honk in hell of being successful
It looks like your friend taped the DMLs to the frame. Keen to know what kind of tape.
Also interested if anyone that has experience with using tape like this and whether it isolates the panel from the frame sufficiently.
One of the membranes with a coil affixed to it is here. Some of them can be seen in the videos here and here.
@ Eucyblues99
One of the individuals who embarked on this "wild goose chase" quite sometime ago, is a successful producer of DMLs and a leading engineer at his firm. He has been, or perhaps still is, a member of this forum and has contributed infrequently to this thread, without divulging any information. If you go back through the old posts here, you might discover who he is. He would always say that he wasn’t supposed to divulge company secrets.Anyway, it doesn’t matter who he is. The original idea is not his, but he has the means to implement it. If your idea of making a DML is to simply stick a shop-bought exciter at the back of the panel, then so be it. Anyone can do that; the instructions are available here for anyone to follow. We are talking about creating DMLs, not just sticking shop-bought exciters to panels, or trying to choose the type of panels or which place to stick them.
I am sure there are others who might want to experiment—really experiment—who might want to create something different, something much more interesting. Someone will catch this idea and try it, and when they succeed, I’d be most happy!
Lehka,
Pardon us if we seem a little jaded. But on occasion we get people who start posting on this forum suddenly, with lots of ideas, who act like they know a lot (some do, some don't), cause a ruckus, and then disappear.
You may be giving off that kind of vibe. And your apparent association with the "other guy" is obvious to many of us, and raises even more alarm bells. I think he was banned twice, if I'm not mistaken. We know who he is. And he may indeed be exactly as you describe. But the issue is, that the whole point of this forum is to "divulge information". And if you only want to try and tease us with carpet videos but not really share details, it's more annoying than it is helpful. So if you want to join us, divulge information, and participate in honest and open give and take, I think you will be welcomed here. Please do.
For myself, I think the idea of a flattened coil and a remote magnet is intriguing. But I share Eucy's skepticism. I'm inclined to agree with him that the magnet weight itself is largely irrelevant. The magnet mass can be supported by a spine, and is largely isolated from the panel in any event by the spider. As far as I'm inclined to believe, the only mass added to the panel by an exciter is that of the coil and coil former, which is on the order of a few grams, and not much different from what a flat coil and a its support would also add.
There's also the issue of linearity. I'm not an expert by any means in magnetic fields, but my best understanding is that the if the separation distance between the coil and magnet change due to the movement of the panel, that's not ideal. But it seems that's inevitable with the designs you are talking about, right? Or not? If not, why not? If so, why is it still fine?
I'm not so sure that I'm right that I can't listen to others. In fact, it's when they can show me that I'm wrong that I learn the most! So, tell us why my inclinations are mistaken. Or show us the the panels you have made with baking parchment. Or show us the data that shows that rounded corners are better. That's how you could really contribute, IMO.
Eric
Pardon us if we seem a little jaded. But on occasion we get people who start posting on this forum suddenly, with lots of ideas, who act like they know a lot (some do, some don't), cause a ruckus, and then disappear.
You may be giving off that kind of vibe. And your apparent association with the "other guy" is obvious to many of us, and raises even more alarm bells. I think he was banned twice, if I'm not mistaken. We know who he is. And he may indeed be exactly as you describe. But the issue is, that the whole point of this forum is to "divulge information". And if you only want to try and tease us with carpet videos but not really share details, it's more annoying than it is helpful. So if you want to join us, divulge information, and participate in honest and open give and take, I think you will be welcomed here. Please do.
For myself, I think the idea of a flattened coil and a remote magnet is intriguing. But I share Eucy's skepticism. I'm inclined to agree with him that the magnet weight itself is largely irrelevant. The magnet mass can be supported by a spine, and is largely isolated from the panel in any event by the spider. As far as I'm inclined to believe, the only mass added to the panel by an exciter is that of the coil and coil former, which is on the order of a few grams, and not much different from what a flat coil and a its support would also add.
There's also the issue of linearity. I'm not an expert by any means in magnetic fields, but my best understanding is that the if the separation distance between the coil and magnet change due to the movement of the panel, that's not ideal. But it seems that's inevitable with the designs you are talking about, right? Or not? If not, why not? If so, why is it still fine?
I'm not so sure that I'm right that I can't listen to others. In fact, it's when they can show me that I'm wrong that I learn the most! So, tell us why my inclinations are mistaken. Or show us the the panels you have made with baking parchment. Or show us the data that shows that rounded corners are better. That's how you could really contribute, IMO.
Eric
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It looked like 2inch masking tape to me ?
I did not see or hear any buzzing going on.
So seemed to be working well.
Not sure of the XO.
Steve.
I am not at all interested in the old hands in this thread, or in how and where to position the shop-bought exciters, the knowledge of which is freely available to anyone here. I’m more interested in the new minds who might still be looking in and are eager to experiment. I shouldn’t have ventured into this lengthy thread, where no new mind would want to wade through. Aside from a long list of patents, which I refer to as the treasure trove, not much can be learned about where to place what type of exciters.
If anyone wants to find some interesting information on magnetism, read this thread carefully. You might discover some quite intriguing facts there. However, on the matter of paper membranes, finely crushed marble surfaces, rice paper usage, etc., you won't find anything in this thread. I have also not written about types of coil wire gauges, types of neodymium magnets, their grades and sizes, resistance of coils, lengths and widths of them, the distances between the flattened coil and the magnet system, and much more. Additionally, I haven't uploaded images of working speaker systems. That could be done if and when some freer minds would tackle the matter, but instead, we have old hands trying to defend their territory.
In a few days, I’ll have something else to play with—a M4 Mac mini—and I’ll be quite busy testing it. Even though I’m old, I love super gadgets—I’ve seen its teardown, and I can tell that it is a design wonder. This thread will fizzle down in time. Maybe one day, I’ll open a new thread; maybe not. Perhaps on the Polish forum.
Instead of glueing a coil to the panel why not glue a piezo driver to the panel and do away with the magnet altogether.
Steve.
Steve.
Has anyone seen this?
It seems there is a new 3d printing filament on the block called Tullomer. It's $275 for 500 grams but may have the properties we are looking for in terms of the required stiffness while still being lite enough? You can print it on most standard 3d printers from what I can tell (however I think he said the printer needs to fast). I don't have the budget for it right now but curious what you guys think? I need to replace some blocks (pulleys for you laymen) on my sailboat and this could fit the bill for that as well perhaps?
https://z-polymers.com/
It seems there is a new 3d printing filament on the block called Tullomer. It's $275 for 500 grams but may have the properties we are looking for in terms of the required stiffness while still being lite enough? You can print it on most standard 3d printers from what I can tell (however I think he said the printer needs to fast). I don't have the budget for it right now but curious what you guys think? I need to replace some blocks (pulleys for you laymen) on my sailboat and this could fit the bill for that as well perhaps?
https://z-polymers.com/
Hello Lekha (and others),
I want to thank you for the information that you give when reading in between the lines.
I think this giving clues, and not tell the whole story at once might be a cultural thing?
I find it interesting but some other forum members seem to be less enthusiastic.
I'm not focusing on your flat coil idea (I did give it a try though with a broken exciter, but the standard coil is probably much to small) because that's yet another variable, and I cannot get a good oversight over the standard things : membrane material/thickness/stiffness/edge damping/exciter placement.
Things that I have found :
- The exciter position as patented mescalito/tefra/Alvipet? seems to work well.
- More exciters always sound more smeared to my ears than a single one.
- Paper/nomex membrane till now best option - two sided 80 g/sqm kraftpaper on 4mm nomex. High efficiency, but a peak at about 3 kHz, semi- independent of size of membrane(?). Tried to fix with weight/small hole but didn't succeed.
- Paper might be such a good material candidate because it has wood fibres in all directions, unlike for instance carbon woven cloth. just a thought.
- I like almost square outline, sounds OK but did not measure.
- Filling the edge all around with pu kit seems to damp a lot of strange high freq peaks radiating from those edges.
- Using a foam surround around the whole panel results in much more low freq output, a flatter response, but also less "magic", although that magic probably was just interesting sounding ringing of the panel.
- Gluing the panel I use fumed silica to thicken the epoxy to get a better bond to the nomex, that probably works a bit lke the marble you mention (providing compression strength). It's not on the very outside of the membrane though.
- Plastic sheet/3d printed membrane is no match to paper panel. This is a pity.
Greetings from Amsterdam, Hans
Hans,
Can you share more details about how you constructed your panels? How much fumed silica did you use? How did you apply the epoxy? etc. Pictures would be great if you have any. Have you weighed your panels? That would also be interesting to know.
Eric
Hi Eric, There's a description and links about my construction method here :
https://www.diyaudio.com/community/threads/dml-pa-systems.390363/post-7575541
BTW this post is about making carbon/nomex panels, but the proces is the same with paper of course.
BTW II I found that spreading the thickened epoxy with a roller works much better and easier than a brush.
I tried the weighing thing (with "finger method", placing weights at - I think- halfway between exciter-edge following several guidelines) but got unpredictable and confusing results with resonances/holes shifting (duh...). It's too complicated for me.
Cheers, Hans
https://www.diyaudio.com/community/threads/dml-pa-systems.390363/post-7575541
BTW this post is about making carbon/nomex panels, but the proces is the same with paper of course.
BTW II I found that spreading the thickened epoxy with a roller works much better and easier than a brush.
I tried the weighing thing (with "finger method", placing weights at - I think- halfway between exciter-edge following several guidelines) but got unpredictable and confusing results with resonances/holes shifting (duh...). It's too complicated for me.
Cheers, Hans
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First and foremost, I think I may have erred in joining this thread; I ought to have started a new one instead. There are bound to be individuals who would be keen to explore something novel, particularly if it stems from a classic concept. As for the notion of encouraging people to read between the lines, that can be quite beneficial, especially when there are curious minds with a more open outlook. A forum is fundamentally a collaborative endeavour, where we share ideas and experiment with different approaches. Therefore, it seems I've chosen the wrong thread to contribute to.
Thank you for your interest. There are a few individuals in this thread who know what I’m referring to; they have worked on it and continue to do so. However, they haven't shared their findings here for the past few years.
For now, I will be opting out of this thread.
Yes, exactly what this forum and thread is. But being a diy forum, shared experiments, specifications, info and pictures of actual builds is of more value than wild ideas that's not been tried and tested. I also fail to understand why we should "read between the lines".