new sub

The title of this thread WAS to be ""New" Sub" but the servers now remove all capital letters and punctuation from thread titles... I was searching for the inventor of the ORIGINAL dual voice coil woofer, and the reasoning behind the actual invention, and I have been finding some REALLY cool stuff! Anyway, I tripped across THIS guy's website: check it out... and all I've got to say is this... "is there no END to the snake oil?!?!" I see it... I understand it... I know what he's thinking... I still don't like it. Here's what I see wrong: (especially in a 700 dollar beta woofer) 1: The driver cone is apparently driven BY THE DUSTCAP. The attachment rod is connected to the center of the dustcap. If this is all one machined piece, it would be better, but still not very good. The dustcap/cone junction would have to be very strong indeed. Two (2) potential failure points there. The driver rod/dustcap connection, and the dustcap/cone connection. Bad. (ESPECIALLY in an abused woofer such as a driver marketed as an "SPL Competition Woofer". I think there's at least ONE member here at our beloved 12volt.com that could vouch for the need, nay - DEMAND, for EXTREME structural integrity in an "SPL woofer". FAR more structural integrity than one small connecting rod could provide.) 2: There is only one attachment point for the voice coil/former. The spider is in the middle. This is REALLY bad. While the symmetrical drive of the equal and opposite voice coil/magnetic field setup is a good thing, and a very desirable "perfect Bl curve" CAN be close to acheived, there is no way to prevent voice coil rub. If the structure that connects the voice coil to the driver rod is a PERFECTLY rigid structure, and the voice coil is also perfectly rigid, this will certainly help, but "perfectly rigid" does not exist, except in a computer. The way I look at this driver, voice coil rub is not a possibility, it's a likelyhood. (i.e. not IF, but WHEN)

codrive.com wrote: That's when it occurred to me that two speaker motors mounted face to face, in a "push-pull" arrangement, would create a motor with double the power capacity. And since they must work in opposite phase, with one coil moving into it's magnet structure while the other coil was moving out of an identical magnet structure, it would create a motor with a perfectly symmetrical Bl curve and cancel any DC offset. Just the thing for a high performance subwoofer!

That's called ISOBARIK, dork, and YOU didn't invent it, like your wording kinda indicates you did... Like I said: "Snake Oil". I will admit, I like the idea, but JBL already has (in my opinion) a "better mousetrap", in their GTi woofers, and Alpine actually did it a few years ago in a mid-bass system. (Anybody here remember that model? Bob? Neo magnet structure, cast magnesium, heatsinked basket... About 5 to 8 years, if I remember correctly) Sound off, kids!It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

haemphyst honey, calm down please... Although your points are relatively valid dear, there are some interesting concepts at work here with possibilities.

haemphyst wrote: The title of this thread WAS to be ""New" Sub" but the servers now remove all capital letters and punctuation from thread titles... I was searching for the inventor of the ORIGINAL dual voice coil woofer, and the reasoning behind the actual invention, and I have been finding some REALLY cool stuff! Anyway, I tripped across THIS guy's website: check it out... and all I've got to say is this... "is there no END to the snake oil?!?!" I see it... I understand it... I know what he's thinking... I still don't like it. Here's what I see wrong: (especially in a 700 dollar beta woofer) 1: The driver cone is apparently driven BY THE DUSTCAP. The attachment rod is connected to the center of the dustcap. If this is all one machined piece, it would be better, but still not very good. The dustcap/cone junction would have to be very strong indeed. Two (2) potential failure points there. The driver rod/dustcap connection, and the dustcap/cone connection. Bad. (ESPECIALLY in an abused woofer such as a driver marketed as an "SPL Competition Woofer". I think there's at least ONE member here at our beloved 12volt.com that could vouch for the need, nay - DEMAND, for EXTREME structural integrity in an "SPL woofer". FAR more structural integrity than one small connecting rod could provide.) 2: There is only one attachment point for the voice coil/former. The spider is in the middle. This is REALLY bad. While the symmetrical drive of the equal and opposite voice coil/magnetic field setup is a good thing, and a very desirable "perfect Bl curve" CAN be close to acheived, there is no way to prevent voice coil rub. If the structure that connects the voice coil to the driver rod is a PERFECTLY rigid structure, and the voice coil is also perfectly rigid, this will certainly help, but "perfectly rigid" does not exist, except in a computer. The way I look at this driver, voice coil rub is not a possibility, it's a likelyhood. (i.e. not IF, but WHEN)

Ok I had to get Don and Tek to help me out with this, but here is what they see. 1) There was no mention of what the cone/dustcap/rod assembly will be. But after doing some calculations on this, if the cone is made of aluminum and thick enough, even if it is turn formed, it will hold. Based on what we can understand of the cad and CoDrives technology/patents, it will most likely be a solid form of either reinforced polypaper, or a metal. This type of design has been done before, but manufacturing was limited at the time due to lack of precision machining equipment. 2) This arrangement is due to the design of the mirrored motors. Now logic would dictate that it is a bad setup, but in truth it is no different that traditional speaker setups. It is just presented in a different package. The intelligence of this design is how the stress is distributed through the the sub's assembly. Similar designs are used in high end speakers for concerts. It allows for really high Xmax numbers with little effort. In the case of this 15" they have here, this has 3" total Xmax. Not too shabby honestly. It's essentially basing the design on "throwing" the signal from one motor to another.

...continued wrote: codrive.com wrote: That's when it occurred to me that two speaker motors mounted face to face, in a "push-pull" arrangement, would create a motor with double the power capacity. And since they must work in opposite phase, with one coil moving into it's magnet structure while the other coil was moving out of an identical magnet structure, it would create a motor with a perfectly symmetrical Bl curve and cancel any DC offset. Just the thing for a high performance subwoofer! That's called ISOBARIK, dork, and YOU didn't invent it, like your wording kinda indicates you did... Like I said: "Snake Oil". I will admit, I like the idea, but JBL already has (in my opinion) a "better mousetrap", in their GTi woofers, and Alpine actually did it a few years ago in a mid-bass system. (Anybody here remember that model? Bob? Neo magnet structure, cast magnesium, heatsinked basket... About 5 to 8 years, if I remember correctly) Sound off, kids!

I don't think he was talking about the cones being face to face. It's the motors themselves. As you can see in the design images, the motors work by assisting each other rather than being stacked on each other. This will greatly reduce the heat being emitted and staged on the sub itself as power is constantly applied to it. We've actually been experimenting with this kind of speaker design as well. We've also come up with a design that has no voice former and no magnet as well. (No it isn't electrostatic technology) We're trying to make essentially an inexpensive panel subwoofer. The big flaw to this person's system would be that this sub will have to have a very interesting box for it. The designer claims it is for a sealed box, but that would create all kinds of thermal stress on the cone as it hits hard for SPL. The only real solution for this would be to setup as a reverse mounting sub. This technology is different than the GTi. It has potential, but in the end all that matters is that it works. I know this works beautifully in an outdoor setup and it should achieve competitive SPL, but without actually seeing it in action, it'll be hard to tell in an automotive environment. We give it an 85% successful design based on known technologies, but we've never seen this kind of assembly in a vehicle. No offense dear, but this guy's "snake oil" seems more like "likely concept" than fiction. I think it is just a misunderstanding. Sadly the website is built for one kind of person: engineer. In this case, the only person who could really understand the WHOLE concept presented here would be someone who is fairly fluent in thermal and mechanical engineering.Never send your ducks to eagle school.

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bellsracer wrote: haemphyst honey, calm down please... Although your points are relatively valid dear, there are some interesting concepts at work here with possibilities.

I was being calm! You should see me if I get excited... LOL

bellsracer wrote: 2) This arrangement is due to the design of the mirrored motors. Now logic would dictate that it is a bad setup, but in truth it is no different that traditional speaker setups. It is just presented in a different package. The intelligence of this design is how the stress is distributed through the the sub's assembly. Similar designs are used in high end speakers for concerts. It allows for really high Xmax numbers with little effort. In the case of this 15" they have here, this has 3" total Xmax. Not too shabby honestly. It's essentially basing the design on "throwing" the signal from one motor to another.

My logic tells me it is a fine setup, with many benefites (many outlined on the webpage) No, I understand that completely, BUT, as I said there is only one attachment point (in the CENTER) for the voice coil and former, and that is a FLEXIBLE point, called the spider. (I know you you know this, I'm just saying) In a traditional loudspeaker, the voice coil former is REALLY attached to TWO points 1: the spider, and 2: the front of the basket, by virtue of being rigidly attached to the back of the speaker cone. Now, while both of those points ARE still flexible, they are only flexible on ONE axis, not three. It allows in and out motion, the X axis, but SEVERELY limits lateral motion on the Y and Z axis. Looking at the voice coil former in the comotion system, there is NO truly rigid secondary mounting point anywhere in the system. (the best they do, is a rod (and I can almost assure you a lightweight one at that - for reduced moving mass) attached to a likely (somewhat) flexible dustcap...) You can duplicate the comotion former installation by holding a pencil in your hand, (the basket) at one point in space. Using you other hand, you can easily move both ends of that pencil through all three axes, even while holding your OTHER hand stationary. THIS is the situation I am seeing with the voice coil setup in the comotion driver. Rubbing is inevitable, ESPECIALLY under high stress operations, like SPL installs.

bellsracer wrote: haemphyst wrote: That's called ISOBARIK, dork, and YOU didn't invent it, like your wording kinda indicates you did... Like I said: "Snake Oil". I will admit, I like the idea, but JBL already has (in my opinion) a "better mousetrap", in their GTi woofers, and Alpine actually did it a few years ago in a mid-bass system. (Anybody here remember that model? Bob? Neo magnet structure, cast magnesium, heatsinked basket... About 5 to 8 years, if I remember correctly) I don't think he was talking about the cones being face to face. It's the motors themselves. As you can see in the design images, the motors work by assisting each other rather than being stacked on each other. This will greatly reduce the heat being emitted and staged on the sub itself as power is constantly applied to it. We've actually been experimenting with this kind of speaker design as well. We've also come up with a design that has no voice former and no magnet as well. (No it isn't electrostatic technology) We're trying to make essentially an inexpensive panel subwoofer.

OK, I did get a BIT excited there... After reading his website quote again, he wasn't truly describing iso loading in so many words, BUT he is still describing little more than isobarik loading at the same time. I say this because isobarik DOES that, it just attaches the motors together via an air mass, between the two woofer cones, rather than a push-pull motor structure on the same voicecoil former. That's all I was saying. I am intrigued by your panel sub, though... I've been trying to design such an animal for years. You should SEE the stacks of designs, drawings, and the garagefull of failed attempts! Never tried without a voicecoil, (not necessarily in the traditional "idea" of a voicecoil), but formerless designs were a big hit, in most of my attempts!

bellsracer wrote: The big flaw to this person's system would be that this sub will have to have a very interesting box for it. The designer claims it is for a sealed box, but that would create all kinds of thermal stress on the cone as it hits hard for SPL. The only real solution for this would be to setup as a reverse mounting sub.

Here again, I stress the stresses that are involved with a PROPER SPL system. Even other drivers, using known, PROVEN (albeit WAY beefed-up) technologies, fail, and often with spectacular results, in the HIGHLY mechanically abusive SPL arena. I don't believe the enclosure would be significantly different, as I am sure this particular driver still adheres to known T/S parameters and rules, and I am not certain that thermally there would be anything more to address than any other high powered woofer system. ANY small enclosure, high powered woofer will need thermal management, and I admit freely that reverse monting of the sub is a very good way to deal with that particular issue.

bellsracer wrote: This technology is different than the GTi. It has potential, but in the end all that matters is that it works. I know this works beautifully in an outdoor setup and it should achieve competitive SPL, but without actually seeing it in action, it'll be hard to tell in an automotive environment.

Well, not really different. The mechanical implementation is different, but the GTI uses dual motors, attached to one voicecoil, in symmetrical opposition, just as this one does. I also don't think I even HINTED that it wasn't going to work, I was really just pointing out what I saw as wrong, (or potentially wrong, depending on your point of view) based on my understanding.

bellsracer wrote: We give it an 85% successful design based on known technologies, but we've never seen this kind of assembly in a vehicle. No offense dear, but this guy's "snake oil" seems more like "likely concept" than fiction. I think it is just a misunderstanding. Sadly the website is built for one kind of person: engineer. In this case, the only person who could really understand the WHOLE concept presented here would be someone who is fairly fluent in thermal and mechanical engineering.

Please... No offense taken, whatsoever. I used the phrase like I did, to simply describe some of the semi-outlandish claims (that I found). Claims that MIGHT do what is purported, but not without some serious drawbacks. Drawbacks that I described, and you understood. Thank you for YOUR input. While I am NOT a thermal dynamics engineer, I believe I have a very firm understanding regarding mechanics; I have just been interested in it and studied it for quite a few years, and having two friends that ARE full-fledged loudspeaker engineers at Harman, in Northridge, CA, I have a bit more foot-in-the-door, as it were, when it comes to understanding some of the mechanical issues when relating to loudspeaker design and operation.It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

That would be the old Alpine "DD" Drive Dave.There is no such thing as free installation!

tcss wrote: That would be the old Alpine "DD" Drive Dave.

Those'd be the ones! Thanks, Bob!It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

[QUOTE=haemphyst] I think there's at least ONE member here at our beloved 12volt.com that could vouch for the need, nay - DEMAND, for EXTREME structural integrity in an "SPL woofer". FAR more structural integrity than one small connecting rod could provide.) Structural integrity? BIG TIME!   When I can take a cone of a injection molded woofer and make it look like swiss cheese it shows how strong a woofer needs to be. When we push 2x or 3x or more to a sub vs what is recomended I know the cone will almost begin to flip inside out!   with a single rod I see it very easy to pull away or crack around that area rendering the sub useless at that point I try not to knock anything untill I try it.   So if one appears on my doorstep for free yes I would use it.   But on the exception of that I wont be going into buying big elaborate equipment when the standard kicker dealer equipment is more then enough to win with. I will read over the spec and such when I have a little more time tomorrow and will probably offer a little more incite and cretique2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR

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zhalverson wrote: Where's the data to back this thing up?!

This is what I'm saying! Sounded to me like an infomercial on PBS, with Billy Mays as the spokesperson! (I hate that guy... freakin' @$$clown!)

zhalverson wrote: Also why is it only "understandable for someone fluent in mechanical and thermal engineering". I'm going to be a senior in mechanical engineering and I don't see much besides some CAD drawings and some claims with no evidence to back them up! You can't get things for free in engineering and any product that claims it does should be highly suspect, as such, I'm highly suspect.

The "understandable for someone fluent in mechanical and thermal engineering" thing is commonplace. If it sounds good to the masses, it must be some new voodoo, that will make it magically better. I was able to see all of the voodoo, and that's why I brought it here. As I stated already, it SEEMS like it would work reasonably enough, I just dont necessarily like ALL of the way it was implemented. I, too raised an eyebrow, knowing just what I know, it sounds(ed) pretty... Billy Mays-ish...

zhalverson wrote: haemphyst: There is never such a thing as a truly rigid anything in engineering (everything deforms).

I know this, I even SAID that in my opening post, I think... to whit:

haemphyst wrote: 2: There is only one attachment point for the voice coil/former. The spider is in the middle. This is REALLY bad. While the symmetrical drive of the equal and opposite voice coil/magnetic field setup is a good thing, and a very desirable "perfect Bl curve" CAN be close to acheived, there is no way to prevent voice coil rub. If the structure that connects the voice coil to the driver rod is a PERFECTLY rigid structure, and the voice coil is also perfectly rigid, this will certainly help, but "perfectly rigid" does not exist, except in a computer. The way I look at this driver, voice coil rub is not a possibility, it's a likelyhood. (i.e. not IF, but WHEN)

zhalverson wrote: That comment just caught my attention. But I do agree. Any joint, especially one in a completely reversed loading situation such as a sub, is going to need some major safety factors built in. "It will hold" only goes so far, metals fatigue, brittle materials have rapid crack growth. Mechanics is largely based in statistics. It's hard to say when things are really going to fail. My point i guess is there is very little data to make any claims on the chances of this thing holding together but remember one thing, nothing is free in engineering! Compromise here and pay there. Weaken joints or make them just strong enough and they will fail sooner, no getting around it.

Exactly. Couldn't have said it better myself! I am a HUGE fan of overbuilding and underpromising. More expensive? Yes, but more reliable, too, AND a happier customer. One happy customer only tells three people that they are/were happy. One UNhappy customer tells TEN! That's a VERY tough ratio to overcome.

zhalverson wrote: That's enough rambling for now.

I truly appreciate YOUR input as well! :::::::::EDIT::::::::: Jeff, anything else that you saw regarding this device? Want to try them out? Maybe for next year?!?It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

DYohn wrote: Looks like an interesting speaker.  HERE's another interesting-looking speaker that I hope to try out soon, the SDX15.

"A double 3/4" (19mm) mounting wall is recommended to flush mount the driver."

I wonder why it is recommended that this be flush-mounted?  I didn't think that was a concern with subs.  Anybody know?

Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.