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Has anybody seen this type of driver before? - Page 2

post #31 of 75
I suspect you are not picturing the device's function properly. The enclosed driver is effectively a bellows. It has it's own supply of air to work with, because it's sealed.
Quote:
Originally Posted by diy speaker guy View Post

I agree wholeheartedly with the first sentence of this post, it's this quoted part I don't agree with.
The 2 cones in this thing are pushing the SAME column of air, that is not the same thing as a manifold where the 2 cones are each pushing the column of air directly in front of them. Doubling up cones, stacking them, or any other alignment where the 2 cones one behind the other is not going to increase Sd, it won't push any more air than a single cone. If it were this easy to increase the driving area in this manner we would see this technology in many areas, not just speakers. The proof is in the measurements though, if this thing were superior in any way measurements would reflect that.
This is super easy to test, like I said, just glue a big dustcap with a hole in the middle on a regular driver. That is the SAME THING, since both cones are attached in the device we are discussing. You will notice a decrease in performance, not an increase, and no increase in Sd or the amount of air pushed for a given input stimulus.
post #32 of 75
Quote:
Originally Posted by imagic View Post

I suspect you are not picturing the device's function properly. The enclosed driver is effectively a bellows. It has it's own supply of air to work with, because it's sealed.

The device's function (like all drivers) is an air pump. You could remove the inner driver completely, seal up the hole in the outer driver, and it would still push exactly the same amount of air.
post #33 of 75
Furthermore (although I don't know why I even bother anymore) if this device worked as claimed, why would they stop at 2 cones? Why not sandwich 10 of them in there (each with a hole in the middle except the last one) and increase the Sd 10x? Or taken to the extreme (albeit impractical due to cone weight) why not sandwich 1000 cones? Do you think that would give you 1000 x more Sd? This is ridiculous, 1000 stacked cones sharing the same "tube" will still push the same amount of air as a single cone with the same cross sectional area.
Edited by diy speaker guy - 12/1/12 at 2:34pm
post #34 of 75
I'm not saying it isn't ridiculous per se as far as designs go... it's a solution to a non-existant problem... but what you fail to grasp is that there are effectively two 'tubes' of air being merged. There's a limit to how much air you can push through any given port size, so that's why the design doesn't have 1000 chambers/cones. But... you're still no getting why it's not the same as two or more cones stacked onto the same voicecoil, sharing the same airspace. By giving the second driver it's own enclosure, it acts as a compression driver. All you need is an 'ah ha' moment to get how it functions. Why you'd choose this over a standard 15" driver is beyond me but that's another story. Some people like to ride Harleys, even though as far as being cost-effective transportation they make no sense at all.

Quote:
Originally Posted by diy speaker guy View Post

Furthermore (although I don't know why I even bother anymore) if this device worked as claimed, why would they stop at 2 cones? Why not sandwich 10 of them in there (each with a hole in the middle except the last one) and increase the Sd 10x? Or taken to the extreme (albeit impractical due to cone weight) why not sandwich 1000 cones? Do you think that would give you 1000 x more Sd? This is ridiculous, 1000 stacked cones sharing the same "tube" will still push the same amount of air as a single cone with the same cross sectional area.
post #35 of 75
Quote:
Originally Posted by imagic View Post

I'm not saying it isn't ridiculous per se as far as designs go... it's a solution to a non-existant problem... but what you fail to grasp is that there are effectively two 'tubes' of air being merged. There's a limit to how much air you can push through any given port size, so that's why the design doesn't have 1000 chambers/cones. But... you're still no getting why it's not the same as two or more cones stacked onto the same voicecoil, sharing the same airspace. By giving the second driver it's own enclosure, it acts as a compression driver. All you need is an 'ah ha' moment to get how it functions. Why you'd choose this over a standard 15" driver is beyond me but that's another story. Some people like to ride Harleys, even though as far as being cost-effective transportation they make no sense at all.

LOL, I don't mean to be rude but I'm still waiting for you to have that "a ha" moment.

The inner cone is not like a compression driver at all, there is no compression going on in that inner chamber. The cones are moving TOGETHER, the volume of the inner "chamber" never changes with cone movement, as the inside of a compression chamber does. The walls of a compression chamber are static, they do not move, that's why you get compression when the driver cone moves. In this case, both cones are moving at the same time, same direction, same speed. There is no compression whatsoever happening in between the 2 cones, the air inside the 2 cones is a static load that has no choice but to move back and forward with the movement of the cones.

PLEASE do an experiment with liquid and different plunger shapes, dual plungers, whatever you like. As long as the plunger cross sectional area remains the same, you can do whatever you like to the plunger geometry and add as many additional plungers (with holes in the middle) as you like, it will always push out exactly the same amount of liquid for a given plunger excursion. That's a liquid pump, but air pumps work the same way.
Edited by diy speaker guy - 12/1/12 at 3:06pm
post #36 of 75
Thanks for taking the time to try and explain Mark. As i feared though it was probably a wasted effort.

diyguy, your analogies are misguided.
post #37 of 75
Quote:
Originally Posted by diy speaker guy 
The cones are moving TOGETHER, the volume of the inner "chamber" never changes with cone movement, as the inside of a compression chamber does. The walls of a compression chamber are static, they do not move, that's why you get compression when the driver cone moves. In this case, both cones are moving at the same time, same direction, same speed. There is no compression whatsoever happening in between the 2 cones, the air inside the 2 cones is a static load that has no choice but to move back and forward with the movement of the cones.

The above description is just wrong and summarizes the source of your confusion.
post #38 of 75
PLEASE explain my error.
Quote:
Compound drivers are unique because there are two cones in tandem which are connected by a "drive link".

That's right from the company's webpage. The 2 cones are physically attached to each other, they can't do anything but move together in the same direction at the same speed. If that is true, there can't ever be any change in the volume of the inner "chamber" so there can't ever be any compression. Please let me know which part you disagree with.

I will readily and publicly admit my error if you can point it out. I'll even start a new thread titled "I was wrong." If there's something to learn here I want to learn it.
Edited by diy speaker guy - 12/1/12 at 3:30pm
post #39 of 75
Quote:
Originally Posted by imagic View Post

By giving the second driver it's own enclosure...

This, I think, is at least part of the confusion. I think you have a dramatically different idea of what's going on in there than I do. Neither driver has a separate enclosure (the way I see the pic on the company site). Both cones are open to the outside air (the inside cone can "see" the outside air through the hole in the outside cone), as well, both cones can "see" the inside of the enclosure the driver will be placed in. I don't see any sealed chambers inside the driver itself, unless there's a third cone hiding in there somewhere. Even if there is a sealed chamber inside the driver itself somewhere, it still wouldn't change Sd.
post #40 of 75
Well, the space between the internal driver and the 'port' on the outer driver is contained by the sealed chamber. The air pushed by the internal driver bypasses the backside of the outer driver, it only goes through the hole. As a consequence, the volume of air that is displaced on each stroke is larger than if there was a dustcap in place of the port. That's the crux of the discussion and I can see how it works. I know I'm right, so...


Quote:
Originally Posted by diy speaker guy View Post

This, I think, is at least part of the confusion. I think you have a dramatically different idea of what's going on in there than I do. Neither driver has a separate enclosure (the way I see the pic on the company site). Both cones are open to the outside air (the inside cone can "see" the outside air through the hole in the outside cone), as well, both cones can "see" the inside of the enclosure the driver will be placed in. I don't see any sealed chambers inside the driver itself, unless there's a third cone hiding in there somewhere. Even if there is a sealed chamber inside the driver itself somewhere, it still wouldn't change Sd.
post #41 of 75
For some reason Bigus doesn't like my analogies, but I'll try one more (and I'll even make it seasonal), since this seems to be an overwhelmingly simple concept to me and no one can point to any specific flaw in my reasoning.

Let's say you had a snowplow with one blade and a snowplow with dual blades, each having the same dimensions as the first plow, one blade in front of the other, the front one having a hole in it. Which plow will push more snow? For each meter driven they will push exactly the same amount of snow (all the snow that is in front of the plow). The extra blade does absolutely nothing but add weight. If you put the blades side by side you could push more snow but not by stacking them. Sd does not increase by stacking surface area, only by expanding surface area.

I have to admit this is not a perfect analogy. The liquid in a tube with a plunger is much better but it's been dismissed out of hand. But thisis still a better analogy than all the others that have been presented by other people. This device is not like a manifold because in a manifold neither cone has a hole in it, and if it did the manifold wouldn't work at all, so a manifold is not a good analogy, it's not the same situation at all. This device is not like a compression chamber because a compression chamber does not move along with the driver.

But I agree, this conversation serves no purpose anymore so I guess I'll quit.
Edited by diy speaker guy - 12/1/12 at 4:47pm
post #42 of 75
Quote:
Originally Posted by diy speaker guy 
That's right from the company's webpage. The 2 cones are physically attached to each other, they can't do anything but move together in the same direction at the same speed. If that is true, there can't ever be any change in the volume of the inner "chamber" so there can't ever be any compression. Please let me know which part you disagree with.

Well, I disagree with your conclusion. The drivers are physically linked, yet the chamber in front of the rear driver does change volume. Not sure how else to say it. Visualize the chamber at the beginning and ending of the driver stroke. I'm not going to draw a picture.
post #43 of 75
This thread makes me laugh so hard.

Cone A (outer cone) separates the atmosphere from the enclosure volume. All of that cone area gets used for Sd.
Cone B (inner cone) separates the atmosphere from the enclosure volume. All of that cone area gets used for Sd.
So, A+B=Sd total.

If there was a dust cap over the hole, sealing off the inner cone, then cone B would separate the inner volume between speaker cones and the enclosure volume. It would not have any interaction with the atmosphere and thus not contribute to adding to the Sd.

In this picture, is the Sd the sum of the 12 drivers or just the opening size? Same concept as this multi-coned woofer.
da8b8443_vbattach244467.jpeg
post #44 of 75
Quote:
Originally Posted by Bigus View Post

Well, I disagree with your conclusion. The drivers are physically linked, yet the chamber in front of the rear driver does change volume. Not sure how else to say it. Visualize the chamber at the beginning and ending of the driver stroke. I'm not going to draw a picture.

Ok, since you and imagic insisted so many times that you are correct, I took a long look at the pics on the company website and NOW I can see a compression chamber. The pic further below on the same page had me confused. I WAS WRONG and I will start a new thread thusly titled if you like.

I'm not ready to admit both cones add together to create Sd larger than cross sectional area (because by definition that is wrong and impossible) but I do see that they are able to use a good portion of the traditionally defined Sd under compression, which may have value but is not the same thing.
Edited by diy speaker guy - 12/1/12 at 6:02pm
post #45 of 75
Quote:
Originally Posted by Looneybomber View Post

This thread makes me laugh so hard.
Cone A (outer cone) separates the atmosphere from the enclosure volume.

No it doesn't, it's got a hole in it.
Quote:
In this picture, is the Sd the sum of the 12 drivers or just the opening size? Same concept as this multi-coned woofer.

No it isn't the same concept, see my reply above. I was wrong about compression but not about Sd. Compression isn't the same thing as Sd, which is defined as cross sectional area. But I don't want to take this any further, I see my mistake and that's all I was after.
Edited by diy speaker guy - 12/1/12 at 6:03pm
post #46 of 75
I'm not sure traditional concept of SD is really helpful here. Mark explained it well enough. There is an SD of the outer driver, and an SD of the inner driver, and both contribute to swept volume.
post #47 of 75
The traditional definition of Sd is fine, it explains why a cone shape doesn't have any more Sd than a flat shape with the same cross sectional area even though there's way more surface area on the cone than the flat disk, and it explains why there is no extra Sd with this driver. Surface area has nothing at all to do with Sd, only cross sectional area. You could make a cone a mile deep with a sq mile of surface area and it wouldn't push any more air than a flat disc of the same cross sectional area. You could put a bunch of extra cones with holes in the middle inside this mile long cone and it still wouldn't push any more air.

I see compression (now that I've looked close) but no extra Sd. None of my analogies were any good for the compression aspect (they weren't meant to be) but they all hold up fine as a comparison to Sd. A manifold is NOT the same thing, it's analogous to a row of snowplows, not a single snowplow with stacked blades one in front of the other.
Edited by diy speaker guy - 12/1/12 at 7:30pm
post #48 of 75
How much sd will you say this have? Because this is pretty much exactly what you have in the CoDrive.
Whats pictured is a 12" mounted normally with a 10" mounted on the back of the baffle playing through a 3" hole in the baffle. And i only drew the baffle, but imagine that they are playing in the same box.
What the CoDrive does is implement this in a more compact form, making the hole for the 10" be in the middle of the 12"

post #49 of 75
As pictured, you have 2x Sd. But this is not even similar to what's in the co drive. In the co drive, the front driver (the baffle covering the left driver in your picture) is moving back and forth in tandem with the back driver. If your picture could reflect that (the baffle sucking in and pushing out with the driver motion) it would be correct. The net effect is zero additional gain added to the driver on the right, or 1x Sd.

The definition of Sd applies to this driver as well as any other. The fact that this driver has a built in compression chamber doesn't change that. It won't push any more air than a flat disk.
Edited by diy speaker guy - 12/1/12 at 9:22pm
post #50 of 75
SD is increased. Cross sectional area is increased. Air moved per mm of stroke is increased.

A "compression chamber" is an unnecessary and misleading description of what is happening.

The pic provided above is accurate. I'm glad someone took the time to create one.
post #51 of 75
Quote:
Originally Posted by diy speaker guy View Post

No it doesn't, it's got a hole in it.
True. I didn't say anything about it being sealed due to the rear cone being an extention of the front cone. I over simplified, but it looks like we're all good to go. Side note, I do like how it has identical, but inverted motors to increase linearity.
post #52 of 75
Quote:
Originally Posted by diy speaker guy View Post

In the co drive, the front driver (the baffle covering the left driver in your picture) is moving back and forth in tandem with the back driver. .

This is where you are confused. The front driver moves back and forth yes, but that is irelevant since the back driver isnt playing into the backside of the front driver, but its sealed off from the front driver. The front driver isnt whats covering the back driver, but the basket and the middle suspension is covering it.
The hole in the front driver is where the back driver is playing through, just like in the illustration i made.

here is another picture for you since it seemes you havent bothered to look around on the CoDrive page...
post #53 of 75
Study the device a bit more, realize what you are saying about a 'moving baffle' is silly, have your ah ha! moment, publish your "I was wrong" thread and get over it. biggrin.gif
Quote:
Originally Posted by diy speaker guy View Post

As pictured, you have 2x Sd. But this is not even similar to what's in the co drive. In the co drive, the front driver (the baffle covering the left driver in your picture) is moving back and forth in tandem with the back driver. If your picture could reflect that (the baffle sucking in and pushing out with the driver motion) it would be correct. The net effect is zero additional gain added to the driver on the right, or 1x Sd.
The definition of Sd applies to this driver as well as any other. The fact that this driver has a built in compression chamber doesn't change that. It won't push any more air than a flat disk.

Edited by imagic - 12/2/12 at 4:51am
post #54 of 75
Quote:
Originally Posted by imagic View Post

Study the device a bit more, realize what you are saying about a 'moving baffle' is silly, have your ah ha! moment, publish your "I was wrong" thread and get over it. biggrin.gif

I'm quoting you but talking to everyone here. I was wrong. I see it now, it came to me while I was sleeping.

Where do you want the "I was wrong" thread? In this subforum or perhaps one of the more populated general subforums?

Sorry for the waste of time.
post #55 of 75
Lols. You are a good sport! I still wonder if the darned thing works. I'm more interested in the motor's design than the silly blowhole.
Quote:
Originally Posted by diy speaker guy View Post

I'm quoting you but talking to everyone here. I was wrong. I see it now, it came to me while I was sleeping.
Where do you want the "I was wrong" thread? In this subforum or perhaps one of the more populated general subforums?
Sorry for the waste of time.
post #56 of 75
Quote:
Originally Posted by diy speaker guy View Post

Sorry for the waste of time.

Don't sweat it.

However, do appreciate the level of expertise of many of the contributors here is, without question, .... world class. This doesn't mean they're beyond reproach, it merely means if they take the time to contribute, take the time to fully assimilate their answer.

Welcome to AVS
post #57 of 75
Quote:
Originally Posted by imagic View Post

I still wonder if the darned thing works. I'm more interested in the motor's design than the silly blowhole.

Perhaps further exploration of the designers inclinations can be the genesis of some real beneficial technology.

This particular iteration however, no dice. Reading, ... I got to "bass speed", or however it was termed, and began to skim much more quickly. I don't appreciate the ambiguity of the tech page cut-away images and explanations etc. Seems purposefully a bit to "smoke and mirrors" for me.

Sound reproduction has characteristics. Here, given the wavelengths inherently involved with bass reproduction, yes .... it does seem as if they're creating an ill-conceived solution to a non-existent issue. Need more displacement? Add more drive units. Space confined? Use a 54mm Xmax RE. Either approach costs significantly less than the aforementioned product.

CoDrive, keep choppin' that wood. Hell, they got Keith Yates attention ..... eek.gif
post #58 of 75
Thread Starter 
Quote:
Originally Posted by FOH View Post

Perhaps further exploration of the designers inclinations can be the genesis of some real beneficial technology.
This particular iteration however, no dice. Reading, ... I got to "bass speed", or however it was termed, and began to skim much more quickly. I don't appreciate the ambiguity of the tech page cut-away images and explanations etc. Seems purposefully a bit to "smoke and mirrors" for me.
Sound reproduction has characteristics. Here, given the wavelengths inherently involved with bass reproduction, yes .... it does seem as if they're creating an ill-conceived solution to a non-existent issue. Need more displacement? Add more drive units. Space confined? Use a 54mm Xmax RE. Either approach costs significantly less than the aforementioned product.
CoDrive, keep choppin' that wood. Hell, they got Keith Yates attention ..... eek.gif

I fully intend to get as much info as possible when I go see his facility. Audio isn't his main gig apparently. The patent for his voice coil design is used in some medical testing devices world wide. At least thats what he said. Hope to have more info soon
post #59 of 75
Quote:
Originally Posted by imagic View Post

Lols. You are a good sport! I still wonder if the darned thing works. I'm more interested in the motor's design than the silly blowhole.

I agree, the motor is interesting. Tho its hardly new, well it looks very similar to JBLs Differential Drive.
post #60 of 75
Can the experts explain how this design enhances Sd (if both cones are mechanically tied together, thus moving as one piston)? Isn't there a single "slug" of air (going through the throat of the outer cone). If the inner driver moved independently from the outer driver, would it be different?
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