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Old 2nd September 2013, 12:32 PM   #331
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Quote:
Originally Posted by Hentai View Post
Hi, nice spiders
What worries me most about these solutions is the uneven distribution of force on the voice coil former. Even with a 4 point cross connection to the chassis in transient times I think the voice coil will get deformed. Usually the dimensions and shape of the voice coil former are just about right to have any disturbing force on one end be reflected to the other end. So if you dont have the same connection all around the former i think it will wobble/rock. Ofcourse magnitude of this will depend on x.
Agree, this worried me too.
But hey, a voice coil former will probably wobble too (standing waves); some manufactures have over one inch between the coil and the base of the cone (the 'neck'). But that is just though experiment of course.
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Old 2nd September 2013, 12:32 PM   #332
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I like the idea of using a spiders web pattern spider What about 3D printing (Shapeways etc.)?

Very very nice speaker builds here btw. DIY at its best!

regards, Daniel
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Old 3rd September 2013, 05:17 PM   #333
Frank40 is offline Frank40  Denmark
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Ok now I know what you mean with the toothpicks spider, thanks. But I see some problem with it. First, the way the toothpicks are placed will create a rotary motion when moving up and down. This will accumulate energy in the toothpicks, because the voice coil is fixed at the cone and the cone will try to hold it in place. Also I am not sure if it's stiff in the sideways movement.

H. A. Hartley solved this in a very neat way. The voice coil is not connected to the spider at all but only the main cone is attached to the spider, the centre cone with the voice coil is the attached to the main cone. This way there will be no outside mechanical interference to the voice coil, other than the point where the voice coil is mounted to the main cone.

The way I am thinking to reduce the stress on the voice coil is to make the former thicker (0.4mm) just over to turns, it will cost me about 100 microgram. Maybe I will try to make the hole thing thicker, this will also make it a better conductor to the cone. But I still need a bright idea for the spider.

Take care
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Old 3rd September 2013, 08:47 PM   #334
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Has anyone really looked into using ferrofluid with a high saturation rating? I am in the process of acquiring some for my mbl project. The following is the information you'll need to get the perfect custom fluid built to your motors needs. http://imgur.com/7Zcs1Ee,9J0wzjE,o53RalD,49EDsKc#0

Last edited by Magnasanti; 3rd September 2013 at 08:56 PM.
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Old 3rd September 2013, 09:12 PM   #335
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Hi, nice spiders

As pointed out there have been many attempts to produce a different (if not better) spider. Some of the ideas mentioned here i think i saw with Rulit's designs.

Frank, that is an awesome looking driver. Congrats!!!



Unfortunately i havent seen any DIY measures of Kms(x) for such drivers. Even to simulate the behavior is a very difficult task and it has been one of the reasons many stay away from these solutions.
But i think the biggest reason (and i may get shot for saying it) is that all these designs bring little or no value to the perceived sound, so manufacturers wont waste resources on this unless they want to market it as such.

What worries me most about these solutions is the uneven distribution of force on the voice coil former. Even with a 4 point cross connection to the chassis in transient times I think the voice coil will get deformed. Usually the dimensions and shape of the voice coil former are just about right to have any disturbing force on one end be reflected to the other end. So if you dont have the same connection all around the former i think it will wobble/rock. Ofcourse magnitude of this will depend on x.

Why not make a spider in a spider's web pattern. From some kind of wire like Frank suggested and this way the connection at the former will be firm because radius get smaller closer to the former and the wires will spread out going outer towards the frame connection. It wont radiate sound, it will have small added mass (to some degree) and it will distribute force equally.

I realize "distribute" is not the correct term... maybe only for restoring force but you get what i mean.

Anyways im working now on a tesla meter tool , want to map the field in the entire gap. I will post more when its ready but i finally got some hall sensors that are small enough and that can measure up to 3T after quite a search.
For a driver with low Xmax it can be possible to scale up a suspension typically used on compression drivers.

http://www.supplierlist.com/photo_im...EPAIR_2425.jpg

Although I don't know if there is any self-torsion throughout the excursion.
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Old 4th September 2013, 06:51 PM   #336
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In my layout I have straight wires; but it is easy to have a bend in them; and then that bend allows for a slack. Subsequently it is possible to have two from a connection point going in two directions.
This solves the twisting motion completely.
One can then weave a little string through the toothpick wires to dampen them, creating a kind of cobweb
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Old 4th September 2013, 07:09 PM   #337
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Quote:
Originally Posted by Magnasanti View Post
Has anyone really looked into using ferrofluid with a high saturation rating? I am in the process of acquiring some for my mbl project. The following is the information you'll need to get the perfect custom fluid built to your motors needs.
I use ferrofluid and have tested a lot of variants...
The best audio quality are without ferrofluid, but I use it to center the voice coil so it is needed. Soon I will test out a minimalistic spider design that have only one mission -> center the voice coil. If I used the variant with stiffer cloth surround I can avoid the ferrofluid / spider, but with the silk surround some centering are required.
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Old 5th September 2013, 04:54 AM   #338
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Exactly what variations did you try and in what field? Did certain amounts of a certain variable negatively effect the sound quality more than others?
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Old 5th September 2013, 11:39 AM   #339
Frank40 is offline Frank40  Denmark
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Well, ferrofluid will not work for me becouse I an useing a feild coil, it will make a mess when turned of
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Old 5th September 2013, 07:13 PM   #340
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Quote:
Originally Posted by Frank40 View Post
Well, ferrofluid will not work for me becouse I an useing a feild coil, it will make a mess when turned of
Oh yeah I know and I posted before with the same reply but some of you seem to not be using the field coil design so I was just wondering.
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