Just as I thought we had covered the bending wave speaker in all its commercial forms another vendor, Audionec (yes, NEC, not NET) popped up on my radar. Pretty impressive designs, especially the modular version.
http://www.6moons.com/audioreviews2/audionec/1.html File these under #Unaffordable but #Cool and #I_have_not_heard_them |
Hello @jwpstayman
Very cool. :) I met the folks from Impact I had no idea there was a connection to the Lineaum.
I like the look of it too, I wonder if you could project images on that screen?
Best,
E
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Hey bdp24
This is staring to sound familiar. Honestly, I'm more than a little surprised that this tweeter design didn't last well into the late 20th and early 21st century. I don't remember hearing it, but it's' innovative design should have made it a long lived classic.
Best,
E
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@atmasphere -
I'm not a Linaeum historian, the only tweeter I know them from was the butt-cheek like driver made famous by Radio Shack.
If they also made an AMT that would be news to me. Let me know if you find a link to one.
Best,
E
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The Linaeum tweeter is a flexible membrane and is excited at the center with the sound wave emitting off the surface as the wave travels from the center to the edge. Right, and if that is accurate, the Linaeum would be a bending wave device but by contrast, AMT’s are excited across the length of each pleat simultaneously. I found this article which was interesting and included more on the subject: http://www.soundimage.dk/Different-col/Bending.htmAMTs are conspicuously absent. I think the only similarity is really in that pleat. Lineaum uses a single pleat as the motor, AMT’s use multiple pleats. AMTs work not by moving back and forth towards the users, but by squeezing air in and out from between the pleats, more like an accordion. More here: https://en.wikipedia.org/wiki/Air_Motion_TransformerAnd here: https://www.audioholics.com/bookshelf-speaker-reviews/monoprice-monolithBut there’s no description for an AMT I’ve ever read where one area of the membrane is excited at one location, and then a wave is transmitted on the surface. Instead, each pleat is like a ribbon’s conductor in a magnetic field. |
That’s fine theoretically but in practice the bottom ported Ohm Walsh
driver produces sound both pistonically and via wave bending at the same
time . But not at the same frequencies. That's what I mean by simultaneously. It is a bending wave transducer to a point, below which it becomes pistonic. |
it woukd seem apparent that the cone cannot be a "rigid" piston. In that case, we do not describe it as pistonic. :) The term comes from the theoretical ideal of having a piston with a flat, infinitely rigid surface, exactly like a piston, operating in a cylinder. |
I don’t have a problem with the text regarding Ohm Walsh. I have a problem with this self contradictory line: Walsh style drivers are essentially specially designed cones that operate pistonically just like traditional dynamic drivers. Pistonically means the cone acts like a rigid piston. You can’t be pistonic and bending wave at the same time, but you can be pistonic for some frequencies and bending wave at others. |
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@mapman
You should read your own posting. Your quoted text directly contradicts your first sentence.
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Are AMTs/folded ribbon drivers bending wave? As I define it, the bending wave is defined by a membrane where one end or point is excited, causing a wave to form on the membrane which tavels to the extremities. A cone, driven pistonically, endeavors to have the same relative motion at all points. Ribbons, AMT's and ESL's are excited across their length simultaneously. There's no wave which travels from point A to point B. Quads however, as I understand them, are in fact bending wave transducers. They are excited at the center, and the wave then travels to the outer edges. |
Right, and I see no evidence that this 8" driver is being used in any other way than pistonic, especially given crossover points.
Mind you, these are very good parts and the speaker may be amazing. I'm just scratching my head over what appears to be shamelessly branding a standard 8" cone with "bending wave."
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Sorry, AMT is not bending wave, Atmasphere. It's motion is pistonic, although at an angle. :)
IMHO, to be a bending wave, the transducer must be excited at one end, and have the sound wave emit off the surface as the wave travels from one end to the other, or from a central point to the edge.
AMT's are driven across their entire length at the same time. There is no start and end to the wave across its surface.
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For historical context, the Ohm Walsh down firing drivers were some of the earliest "bending wave" drivers if not the first. There have also been other attempts at creating mega speakers from bending wave type of drivers like this one from Impact (long gone): https://www.stereophile.com/floorloudspeakers/648/index.html |
