It might be bigger than you think. The problem is more if it starts to sound like global feedback or something, then cost is irrelevent.
I've seen some prelim on a driver using some SOTA materials tech to get a super rigid piston, driven by what are referred to as digital actuators with location feedback. It's supposed to be low cost to make in volume. Of course, in getting from research to reality a lot of dropouts occur....
What bugs me is, why is a conical driver shape used? The surface pushing the air is not normal to the direction of propagation, but at an angle.
jn
jn
Mechanical advantage. Still has the same forward propagation for a given diameter. Not to say one couldn't design a pretty clever shallower cone angle based on a skin/core design (with a tapering core)
Really? There are lots of reasons. How flexible is a piece of paper laying flat, now shape it like a cone...
From what I know FAL had a high end one but it has some kind of resonance or distortion that has stopped wide use. It seems it would be easier to succomb to since you have a straight shot across the cone, so if it is stiff enough it probably isnt damped much. (Or it is heavy as hell)
That all makes sense why planars we do see tend to have driving forces that are relative to the size of the diaphram like on Martin Logan speakers, which are still curved some. They don't need as much stiffness since they have equalish pressure for movement.
I suspect flat drivers could work if you wanted to have numerous drivers as to avoid certain problem frequencies on all of them.
The stuff I was shown used a flat piston, similar to the old Kef B139, but with *much* better materials...
Did the digital actuator appear to be compitent? I haven't looked at them before. I just assume they would have a hard time.
SOTA materials might be a better approach to the problem, especially better 'surround' material for longer throw. Linear actuators have been adapted to speakers for at least the last 25 years.
It was a rhetorical question. At relatively low frequencies, one can assume the entire mass of air being pushed around is being pushed uniformly. I just wonder at what acceleration does that start to fall apart.
Has anybody tried a spherical surface such as a dust cap the size of the cone, more like a dome tweeter but shallower? It would be force driven from the outer edge of the driver.
In that case, why not get rid of the intermediary and make a vc 12 inches in diameter? That would be so much fun..
Even better, 5 or 6 concentric voice coils mounted to a flat plate, starting at 2 inch diameter and each 1 inch diameter bigger, with neodyms in circular rings in between the vc's thick enough to give gaps around each vc..
jn
ps...imagine a BL product of 15 or 20 thousand..😱
Has anybody tried a spherical surface such as a dust cap the size of the cone, more like a dome tweeter but shallower? It would be force driven from the outer edge of the driver.
In that case, why not get rid of the intermediary and make a vc 12 inches in diameter? That would be so much fun..
Even better, 5 or 6 concentric voice coils mounted to a flat plate, starting at 2 inch diameter and each 1 inch diameter bigger, with neodyms in circular rings in between the vc's thick enough to give gaps around each vc..
jn
ps...imagine a BL product of 15 or 20 thousand..😱
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it might be easier to measure once for a driver type and create a digital map to predistort a signal before it goes to the driver.
I was thinking that by alternating vc and neo magnets, I would use both sides of each magnet, and I would need one return structure from the outer vc to the inner one. By arranging the magnets correctly, the flux lines through the vc's would all be in the same direction. Think of a Stonehenge, with all the neo magnets arranged north pole towards the center. The speaker membrane (sheet titanium for example, would have considerably uniform pressure because of the distributed voice coils.
I suspect a structure like that would be best loaded by a horn, and that it would need a very high compression ratio for efficiency.
jn
I suspect a structure like that would be best loaded by a horn, and that it would need a very high compression ratio for efficiency.
jn
As I was reading your reply I was certainly thinking that it would take some power to move it. That's not *bad* but it costs more.
You'd probably use sandwiched honeycomb, the latest thing. The honeycomb can damp some, but remain very rigid since it's sandwiched by such strong materials that don't have much besides tinsel strength at their thickness. But actually I wonder if something like cork could be more ideal with some carbon strands in it.
You'd probably use sandwiched honeycomb, the latest thing. The honeycomb can damp some, but remain very rigid since it's sandwiched by such strong materials that don't have much besides tinsel strength at their thickness. But actually I wonder if something like cork could be more ideal with some carbon strands in it.
Carbon graphite thin flat top and bottom, sandwiching graphite thin wall tubes in a honeycomb pattern. The fixturing would be concentric rings of aluminum that position the vc's, with reliefs for the wires. The vc's prewound double layer, the formers two layer graphite cloth that splays out onto the flat diaphram. The final glue-up assembles the honeycomb, the vc's, the coil wires all with fixture precision.
The neo's can be potted one ring at a time, again with placement fixturing. Don't know if it would be better to buildup outside in or inside out.
Jn
The neo's can be potted one ring at a time, again with placement fixturing. Don't know if it would be better to buildup outside in or inside out.
Jn
You sure that randomized damping in the sandwich isn't useful?
It's so fun feeding other people IP, isn't it?
It's so fun feeding other people IP, isn't it?
There was a car audio woofer like this 20 years ago. I don’t know if it ever saw production but it was quit impressive. I think it was carbon and maybe Kevlar honeycomb.
No, I am not sure. But my suspicion is that front to back relative vibration is probably very little with carbon graphite, so internal damping may not have much to do. I would want the structure resonances well above the operating range.
It is. I find for the most part, not many listen anyway, and fewer care.
There are the occasional exceptions, and it is nice when that happens.
Jn
Well, it is possible that someone co-developed something posted by someone with Folsom, but we are fairly confident a major company copied something of ours... It is kind of an honor in a way. Luckily it is a very dated design, to which we have updated many times since.
If this cone is stiff enough, then I maybe you can keep resonances high. But lower frequencys will have a tendancy to ooze across it, which might make some secondary resonance. Regardless, I want to hear it now.
If this cone is stiff enough, then I maybe you can keep resonances high. But lower frequencys will have a tendancy to ooze across it, which might make some secondary resonance. Regardless, I want to hear it now.
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