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Multi-Way Conventional loudspeakers with crossovers

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Old 5th April 2013, 09:33 PM   #211
Hentai is offline Hentai  Romania
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Hi Frank, yep that is your motor.

Spider has a mass component as well. So if you think using 2 spiders and no outer suspension will yield lower mass, you have to calculate spider mass as well.

tinitus has a a point. Think of guitar louspeakers. These extend well in the upper midrange section, one can think of them as wide range speakers. But what we need to think about is wide range and low distortion, something a small spider can't provide.
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Old 5th April 2013, 09:35 PM   #212
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Originally Posted by Frank40 View Post
Hi to all

Jef,
I relay like your idea, I have been thinking along those lines. But the thing I wasn't sure of was if the suspension coil will fix the voice coil in both directions X and Y.

Take care
Frank
Radial centering is possible with ferrofluid. between the inner voicecoil and the polepiece. That is the main reason why the motor has two airgaps to hold the whole cone with ferrofluid stable as there is no surround. After simulating this structure i found out that the double airgap brings a lot more flux density to the bottom airgap. (two magnets opposite to eachother, they wil attract eachother because of the iron between them) Axial centering is also possible due the use of a second underlying coil. => the main advantage is that you can soften or harden the suspension like disired. But the main advantage is that the suspension has the same force reduction as X increases like the voicecoil (see curve i posted). So X-I curve is full lineair. i think is almost impossible with a normal spider. The first type is already made and working but the parameters were the worst ever (nothing was calculated) now with the new motor system everything looks good on paper. Within a few weeks it must be ready to test.
It is possible to drive the suspensioncoil with a current driven source this eleminates the fluctuating inductance till 20Khz
It is also possible to drive the suspension with a voltage driven source the inductance wil fluctuate in the same way as the voicecoil so this effect on both the suspension and voicecoil will compansate eachother.
So X is more lineair but Q will fluctuate in this case. With a total BL of 20NA I think this is less or even not noticable.

For the cone still searching for the ideal solution but you guys already helped a lot. gonna research some suggestions. start with glassfibre...

Thx.

Last edited by Jef Nuyts; 5th April 2013 at 10:04 PM.
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Old 5th April 2013, 09:57 PM   #213
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Originally Posted by Hentai View Post
a couple more pics of the 124mm diameter motor

Very nice machinery man. What type of steel you using?

Like you say paper cones... all the best but how to make it like manufactures can, Nothing on the internet of this. Don't know how to start on these.

Keep up the good work
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Old 6th April 2013, 10:09 AM   #214
Hentai is offline Hentai  Romania
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what is the final weight? I am a bit concerned don't think the basket I am using now is strong enough to hold it.
Haven't weighted them yet but i would expect around 15kg. It will definately not hold with just the holes in the frame. You need to make a holder for the motor inside the speaker so that the motor rests on something solid.

Jeff for cones it all depends if you want it conical or curved.
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Old 22nd April 2013, 10:06 PM   #215
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i don't know if that would be helpfull for You ( haven't seen anything on that in this thread ) but you can actually try to make paper pulp of some kind and apply it on the surface of the mould ( previously coated with something non sticky ) - or just try to make positive mould out of negative mould the same way and use it as a press for making cones - also when it comes to fiberglass maybe if it's so lightweight it's better to try to make sandwich of some kind out of it instead of multi layered cones ( the fact is that this kind of structure should be way more rigid ) - this way You could even create cone that would be fiberglass on the inside of speaker and paper on the outside ( and I didn't figured out what could be in between as of yet but eton springs to mind with theirs honeycomb of some kind )

great work - I'm highly impressed
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Old 23rd April 2013, 06:53 PM   #216
Frank40 is offline Frank40  Denmark
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Hi piotr z

I did try making a cone from paper pulp but it did not work out for me, it wasn't as easy as I thought. Making a composite with fibre glass is definitely a possibility, but it will ad to the mass.
But in the end it is all about finding the sweet point between weight, stiffness and damping of the cone.

I did managed to make a spider and a cloth surrounding, still waiting for the epoxy to cure fully.
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Last edited by Frank40; 23rd April 2013 at 07:01 PM.
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Old 23rd April 2013, 07:20 PM   #217
tinitus is offline tinitus  Europe
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hey, using a spider for the surround, thats clever

do they have them somewhat smaller ?

btw, I have a DIY cone I made using lighter foaming poly glue
I can post pics if interested
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Old 23rd April 2013, 07:45 PM   #218
Frank40 is offline Frank40  Denmark
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Hi tinitus

The surrounding is not a spider, it is made from viscose cloth and epoxy. But the spider is around the same size as the cone. Yes.... please post a picture of your cone, I would love to see it.

Take care
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Old 24th April 2013, 09:12 PM   #219
Hentai is offline Hentai  Romania
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I can post pics if interested

definately interested. Please post.
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Old 24th April 2013, 09:12 PM   #220
Hentai is offline Hentai  Romania
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Originally Posted by Frank40 View Post
Hi piotr z

I did try making a cone from paper pulp but it did not work out for me, it wasn't as easy as I thought. Making a composite with fibre glass is definitely a possibility, but it will ad to the mass.
But in the end it is all about finding the sweet point between weight, stiffness and damping of the cone.

I did managed to make a spider and a cloth surrounding, still waiting for the epoxy to cure fully.
wow surround looks awesome. Good work!
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