either I dont understand what you say, or you are just explaining the obvious 🙄
Pictures of this flat magnet reel might tell more than words 🙂
To me there are only two options fore doing the "coil" winding, and Im not thinking about "wire" material
Either one layer in between the two diaphragm halfs
Or lay the "winding on the outside, which gives a "coil" wire with twice as long, or it could be thicker/wider
Which to prefer will be a matter of impedance
One layer in the middle might be symmetrically better, but a differense that may not matter much, I dont know
Fore "coil" wire it would be very simple to just use the food wrapping foil/paper so successfully used by many diy ribbon builders over the years
It can be easily cut into any size needed, and its very light with pretty thin foil, giving higher impedeance
But impedance measurements have to be done, to know how much length is needed, or to evaluate whether enamelled wire will be better...or magnet tape, whatever that is
Fore sure, paper quality will matter, as will all kinds of coating
Hydrogene peroxyde(waterglass) is one option with attractive qualities, but its waterbased, and the paper might not like it so much
Other substance like softened shellack or linseed oil with dryer might be better
Or a combination
All used in violin building....but hairspray is not
Just keep in mind that fore high frequency and sensitivity weight is an important factor
edit, Im not sure that a single module of 500-600mm is a line source at all
If it was a tweeter only, then yes
But not so much when used in low midrange
I would rate it more like a big 12" fullrange, with a bit of vertical "concentric" nature like a Quad ESL, or even a vertical "coax"
Might be good so, or just result in phase issues, lobing or whatever
Pictures of this flat magnet reel might tell more than words 🙂
To me there are only two options fore doing the "coil" winding, and Im not thinking about "wire" material
Either one layer in between the two diaphragm halfs
Or lay the "winding on the outside, which gives a "coil" wire with twice as long, or it could be thicker/wider
Which to prefer will be a matter of impedance
One layer in the middle might be symmetrically better, but a differense that may not matter much, I dont know
Fore "coil" wire it would be very simple to just use the food wrapping foil/paper so successfully used by many diy ribbon builders over the years
It can be easily cut into any size needed, and its very light with pretty thin foil, giving higher impedeance
But impedance measurements have to be done, to know how much length is needed, or to evaluate whether enamelled wire will be better...or magnet tape, whatever that is
Fore sure, paper quality will matter, as will all kinds of coating
Hydrogene peroxyde(waterglass) is one option with attractive qualities, but its waterbased, and the paper might not like it so much
Other substance like softened shellack or linseed oil with dryer might be better
Or a combination
All used in violin building....but hairspray is not
Just keep in mind that fore high frequency and sensitivity weight is an important factor
edit, Im not sure that a single module of 500-600mm is a line source at all
If it was a tweeter only, then yes
But not so much when used in low midrange
I would rate it more like a big 12" fullrange, with a bit of vertical "concentric" nature like a Quad ESL, or even a vertical "coax"
Might be good so, or just result in phase issues, lobing or whatever
Pardon my correction, but waterglass is actually a solution of sodium silicate / metasilicate, not hydrogen peroxide.
http://en.wikipedia.org/wiki/Sodium_silicate
Still, it is an interesting notion, to use this to re-enforce a paper diaphragm. It might require some heat to stabilise the silicate.
That aside I would like to say this thread is still taking some interesting turns. The temptation to build something similar to these devices is definitely lurking 🙂.
Ed
http://en.wikipedia.org/wiki/Sodium_silicate
Still, it is an interesting notion, to use this to re-enforce a paper diaphragm. It might require some heat to stabilise the silicate.
That aside I would like to say this thread is still taking some interesting turns. The temptation to build something similar to these devices is definitely lurking 🙂.
Ed
Has anyone considered using a length of flex p.c strip for the voice coil. I was looking at building this design several years ago and that seemed to be apossibility . the stuff I am referring to is used to connect between p.c. boards and consist of copper foil conductors fastened between sheets of I believe it is kapton film, so pretty much voice coil material already.
just a thought
just a thought
tinitus said:
Sorry,I was trying to make a comparison to something already well known. Not "magnet tape" but "magnetic tape" - tape recorder tape. Reel to reel tape. "Open reel."
This stuff:
An externally hosted image should be here but it was not working when we last tested it.
But that comparison was just to try and explain "pancake" flat edgewound voice coils.
Imagine if one of these empty reels was a rectangle, instead of a circle. Say the center hub, or axle is 25 cm tall and only 2 cm wide. (and only 3 mm thick)
Then imagine you had enamel coated copper wire that was sort of shaped like that recording tape, but not as flat. -- maybe a cross section of 1.5mm (wide) by 0.5 mm thick.
Then wind about 60 turns of the flat wire onto the rectangular spool.
That's it. Sorry for the confusion.
Ed Holland said:
Ed, I seem to remember you threating to make one of these a year or two ago, and even mentioning that you made some sort of prototype back then?
OK, Everyone:
Where can I buy voice coil wire?
I want flat, normal, aluminum, coated voice coil wire.
I do not want a shipping container or even a pallet of it. just a small spool for now.
Ideas?
amp-guy said:
Thats an interesting idea
If there is a solid way to make the connections
Earlier I said there would be two options fore placing "coil wire"...in between diaphragm, or on the outside
Well, there is yet another and obvious option
A combination of both, would give 3 layers
That means fore a 500mm unit it would result in 3 METER "coilwire" fore just one round of "winding"
"Waterglass" as we call it in danish....seems I have been reading the wrong bottle
It says "Natron-waterglass" on the right bottle
Seems "natron" means "soda" in english
A connection of kiesel and sodium
Also says content of "dinatriummetasilicate"
Useable as primer on constructions like concrete
Or previously used fore conservating eggs
Also found on old Strad violins as well, but may have different origin like vulcano ash, but they really dont know
Makes the wood very hard and moist resistant
JBL have advertised about it too
I believe its "basic", depending on strength of solution
Ahhh, found it
"sodium silicate"
Hope that clears up confusion about "water glass/liquid glass" (my mistake)
But as said, "hairspray" might be a very good alternative, its very easy to handle
And it wont "deform" the paper, or ad much weight
Though there may be very different kinds
"sodium silicate"
Hope that clears up confusion about "water glass/liquid glass" (my mistake)
But as said, "hairspray" might be a very good alternative, its very easy to handle
And it wont "deform" the paper, or ad much weight
Though there may be very different kinds
amp-guy said:
Gotta love Kapton, but is there a reason that we may want the voice coil itself to be flexible? I was thinking more in the direction of "as rigid as possible within the limits of low mass."
I think Kapton film is used in recent conventional voice coils because it stands up to heat well, and heat is a huge issue in voice coils. If it wasn't for heat and resistance, we would make the voice coil wires infinitely small.
I really like the idea of using something already existing like that though, and definitely a stack of these could stay pretty thin.
I was also wondering if there may be any use for ferrofluid in the suspension to promote gap centering and cooling. My guess is that it may have problems in a really high frequency driver, but may still be worth looking at. But actually, it may just drip to the bottom of the magnet assembly though.
I would love to avoid using elastic bands for the suspension. They seem to be a bit of a sloppy fix for suspension. A good spider is very flexible front to back, and very non-flexible up-down and left-right, so it doesn't interfere with the correct travel of the cone much at all. Elastic seems like it will add mass, and extra resonances (like a guitar string) and would tend to impede the intended travel (front to back) as much as it does the undesirable movement (up-down, left-right).
If the voice coil former was made of graphite, how strong would diamagnetic forces be in a 1-2 Tesla field? Normally diamagnetic forces can just be ignored, since they are so darned small, but for a highly diamagnetic material like graphite in a pretty darned strong field, it may be useful for gap centering. (It only took 16T to levitate a frog...)
Sounds like we are getting a bit wild here 😀
But elastics fore centering is no big issue, but I do agree that the stored energy of elastics is best avoided
We could call the release of its energy "chaos oriented"
It could easily be replaced by a small strips turned 90 degree
Any material could be used, even paper 😉
Whats it called in english..."leaf-spring" ?
My concern at the moment is the point where the "coil-wire" leaves the diaphragm fore the speaker terminals
But the outcome of many of these issues still depend on how much you expect this thing to move
Regarding stiffness and stability of the "voice-coil" part of the diaphragm placed in the gap
I believe epoxy glue, Araldite or whatever would take care of that
Just place the paper under pressure between two 100% straight pieces of wood
But 100% accuracy will be essential on this point, so that the "coil" will be seated perfectly in the gap
It will be tricky, but doable
But elastics fore centering is no big issue, but I do agree that the stored energy of elastics is best avoided
We could call the release of its energy "chaos oriented"
It could easily be replaced by a small strips turned 90 degree
Any material could be used, even paper 😉
Whats it called in english..."leaf-spring" ?
My concern at the moment is the point where the "coil-wire" leaves the diaphragm fore the speaker terminals
But the outcome of many of these issues still depend on how much you expect this thing to move
Regarding stiffness and stability of the "voice-coil" part of the diaphragm placed in the gap
I believe epoxy glue, Araldite or whatever would take care of that
Just place the paper under pressure between two 100% straight pieces of wood
But 100% accuracy will be essential on this point, so that the "coil" will be seated perfectly in the gap
It will be tricky, but doable
Yes, but that was all talk 😀 , I never took it further... I've tried a few ideas, but they have all been very low efficiency mock-ups. It's very easy to make something that makes sound. It's not so easy to make lots of good sound 🙁 The 360 degree quasi ribbon was pretty good, but needed a lot more magnet and better ideas for support to be feasible.
As for diaphragm suspension, what is needed is some kind of flexure - basically a springy strip of a suitable material. This could offer restoring force in one direction and the rigidity to preserve alingments in another.
Ed
Ed Holland said:
Yeah, thats what holds us back, and what keeps the talking going
And what I want to do, and feel is needed to make this thing really sing, that could literally take off a finger or two
take a look at the Lineaum....
no real need to re invent the wheel here as you are for all intent building a Lineaum. See what worked and was practical in a real production product. Once you build one you can optomize materials all you like.
I still think the a light syntheric woven fabric is a very good choice for the diaphragms as the weave will provide energy loss and self damping to structural resonances. Polyester silk screen fabric would be my first choice. In the Lineaum design the diaphragm is a soft lossy material not mylar as many have claimed. So my suggestion of a polyester woven fabric light but lossy. A fabric could even be viscous damped with silicone fluids. An almost 360 degree version could be built with a single loop of fabric diaphragm clamped at one end and driven at the other. Just some thoughts. I cannot help but think that all of this would infringe on the Paddock patents if someone was considering a commercial endevour. Google them up they are full of good information.
no real need to re invent the wheel here as you are for all intent building a Lineaum. See what worked and was practical in a real production product. Once you build one you can optomize materials all you like.
I still think the a light syntheric woven fabric is a very good choice for the diaphragms as the weave will provide energy loss and self damping to structural resonances. Polyester silk screen fabric would be my first choice. In the Lineaum design the diaphragm is a soft lossy material not mylar as many have claimed. So my suggestion of a polyester woven fabric light but lossy. A fabric could even be viscous damped with silicone fluids. An almost 360 degree version could be built with a single loop of fabric diaphragm clamped at one end and driven at the other. Just some thoughts. I cannot help but think that all of this would infringe on the Paddock patents if someone was considering a commercial endevour. Google them up they are full of good information.
Yes, yes and yes
But I do believe the only real genious trick with the Rubanoide design actually is exactly the tension in the diaphragm, which correctly adjusted on its sides, will keep it in place
No doubt, there will most likely also be all sorts of ressonance problems
But wont that the same issue with any other ribbon, planar, ESLs the famous Manger, or Lowthers etc
But I do believe the only real genious trick with the Rubanoide design actually is exactly the tension in the diaphragm, which correctly adjusted on its sides, will keep it in place
No doubt, there will most likely also be all sorts of ressonance problems
But wont that the same issue with any other ribbon, planar, ESLs the famous Manger, or Lowthers etc
Here is what I was thinking of for the V.C. Digikey has this sfuff in stock in up to 18" precut (cheap) or 500' rolls ($$$) I have used this stuff before but not to make a lineaum, it is copper it will solder or there are very solid reliable coonectors. it is polyester so adhesives and resins will bond effectively.
http://www.parlex.com/tech_library/ps-2562.pdf
actually the stuff is fairly stiff, and less mass than an etched frp
glass pcb..
I have wondered why every effort to put a lineaum driver on the market seems to fall flat . I have a set of the old Rat shack Lineaum tweeters laying around that never fail to impress when I have hooked them up, but I feel the real potential lies in a full range driver.
http://www.parlex.com/tech_library/ps-2562.pdf
actually the stuff is fairly stiff, and less mass than an etched frp
glass pcb..
I have wondered why every effort to put a lineaum driver on the market seems to fall flat . I have a set of the old Rat shack Lineaum tweeters laying around that never fail to impress when I have hooked them up, but I feel the real potential lies in a full range driver.
perhaps....
The suggestion for the polyester silk screen material is also partly because it is able to hold itself up and weighs less that a solid film which would be able do the same and also be as lossy. This design is not the same as a planar one in which a very thin film is used under tension. Structural resonances will be similar to those of a cone design but there is no diaphragm termination over most of the diaphragms exposed edges so resonance is a big issue and hence my suggestion of a woven fabric (one in which the weave permits equal motion in both directions,length and width). Termination or suspension is a rolling type as in the Lineaum. So there will be considerable reflection there and as I said zero termination along the top and bottom edge of the diaphragm foil. Perhaps a damped structure could house the "loose edges" of the diaphragm and minimize that problem?
The suggestion for the polyester silk screen material is also partly because it is able to hold itself up and weighs less that a solid film which would be able do the same and also be as lossy. This design is not the same as a planar one in which a very thin film is used under tension. Structural resonances will be similar to those of a cone design but there is no diaphragm termination over most of the diaphragms exposed edges so resonance is a big issue and hence my suggestion of a woven fabric (one in which the weave permits equal motion in both directions,length and width). Termination or suspension is a rolling type as in the Lineaum. So there will be considerable reflection there and as I said zero termination along the top and bottom edge of the diaphragm foil. Perhaps a damped structure could house the "loose edges" of the diaphragm and minimize that problem?
Why no commercial...
Well, theres lots of fine designs that doesnt last long as commercial units, even some of the finest kind
Might be due to all sorts of things
Stability issues
Demands fore frequent adjustments
Production problems
Quality issues
Proper material fore crutial parts missing
Lack of proper attractive design
Looks too much like prototype
Too few potential customers
Only function in specialised arrangement
No dealer network
Price
Looks
Lack of financial interest
No investors
Well, theres lots of fine designs that doesnt last long as commercial units, even some of the finest kind
Might be due to all sorts of things
Stability issues
Demands fore frequent adjustments
Production problems
Quality issues
Proper material fore crutial parts missing
Lack of proper attractive design
Looks too much like prototype
Too few potential customers
Only function in specialised arrangement
No dealer network
Price
Looks
Lack of financial interest
No investors
I know we should really stay away from the very strong neos
But I really do think they are essential fore this
Or at least, I dont think I will bother with it otherwise
As I can get quite stubbern some times, I have found an almost safe way to assemble the magnet/pole unit
Magnet I would like to use is 2"x1"x3/4" N50, pulls 142pound, quite hefty fellow
Theres also a 1"x1"x1/2" N50, pulls 58pound, and much easier to handle
Or maybe alternatively consider disc magnets
All magnets should be placed several meters away from the unit to be assembled
My guess is that 1 meter is not safe enough, as they may very well come flying like rocket
Every magnet handled should be marked carefully
Polarity is best found with a small magnet, of which you have marked polarity also
When handling a magnet its best to have a tight grip of the thing
But not when placing it, best to let it go if one cant hold it
Pole unit should be firmly secured, before placing any magnets are placed
A wooden plate could be placed between magnets when placing the first row of magnets
That way the magnet to be placed wont be able clash together with previously placed
A wooden stick and hammer might be needed to get them lined up perfectly
To get the remaining poleplate in place is best explained by the drawing below
Threaded rods with nuts(8mm) are used to control this exstremely dangerous part
One poleplate should have threads fore the rods
Still great risk of something unpredictable and very bad could happen
So all fleshy parts should kept on a safe distance at all times
But I really do think they are essential fore this
Or at least, I dont think I will bother with it otherwise
As I can get quite stubbern some times, I have found an almost safe way to assemble the magnet/pole unit
Magnet I would like to use is 2"x1"x3/4" N50, pulls 142pound, quite hefty fellow
Theres also a 1"x1"x1/2" N50, pulls 58pound, and much easier to handle
Or maybe alternatively consider disc magnets
All magnets should be placed several meters away from the unit to be assembled
My guess is that 1 meter is not safe enough, as they may very well come flying like rocket
Every magnet handled should be marked carefully
Polarity is best found with a small magnet, of which you have marked polarity also
When handling a magnet its best to have a tight grip of the thing
But not when placing it, best to let it go if one cant hold it
Pole unit should be firmly secured, before placing any magnets are placed
A wooden plate could be placed between magnets when placing the first row of magnets
That way the magnet to be placed wont be able clash together with previously placed
A wooden stick and hammer might be needed to get them lined up perfectly
To get the remaining poleplate in place is best explained by the drawing below
Threaded rods with nuts(8mm) are used to control this exstremely dangerous part
One poleplate should have threads fore the rods
Still great risk of something unpredictable and very bad could happen
So all fleshy parts should kept on a safe distance at all times
Attachments
Did you get a good look at valvitude's frame/magnet assembly on his tall ribbons over here?
http://www.diyaudio.com/forums/showthread.php?s=&threadid=104748&perpage=25&pagenumber=6
He used threaded rods and a strong custom built stand. He also used superglue on one side and epoxy on another side of each magnet.
These huge Neos just scare me with their bone-crushing power.
Makes me want to re-try those electromagnet calculations again. Yikes!
http://www.diyaudio.com/forums/showthread.php?s=&threadid=104748&perpage=25&pagenumber=6
He used threaded rods and a strong custom built stand. He also used superglue on one side and epoxy on another side of each magnet.
These huge Neos just scare me with their bone-crushing power.
Makes me want to re-try those electromagnet calculations again. Yikes!
a.wayne said:
I think he was primarily using the crazy glue to hold the magnets still while the epoxy was setting.
In any case whatever he did completely worked in a very tall ribbon with big Neos holding a 20mm gap.
I have seen others on this forum using only crazy glue.
Why do you say it won't work?
Personally, I can't get it to work even in applications that call for it specifically, like keeping a rear view mirror attached to a windshield in a car. Those kits come with 2 bits of cleaning liquid (alcohol and acetone) so I am guessing that some of the crazy glue failures are in surface prep.
("crazy glue" = "super glue" = cyanoacrylate based fast-acting glue -- I am not sure if the brand names are used outside the US)