Project Ryu - DIY Field Coil Loudspeaker

[badman]

Originally Posted by Frank40

Can some one tell me if the Faraday ring should have electric contact to the pol or not, I can't figure out what is best.

Also.. Do you know what kind of glue to use for holding the wire on the voice coil base.

Hentai, Looking forward to hear what happens when you short one of your wingding on your voice coil.
Is the FEMM a free softweare, and if so where can I find it.

IMHO, definitely should have conductivity between the shorting ring and the pole.

[Marcos_SuperSom]

Frank40 nice vacuum former to cones. And with paper, dont work??? Wet the paper with water or resin and apply the vacuum....its possible???

Thanks

[Frank40]

Thanks for your replay, badman

Marcos_SuperSom, I don't think a vacuum forming is the way to go if you want to use paper.

[Hentai]

Hi all,
A good choice for glue is hernon. I used it and also used resin. You can apply by brush. If voice coil will not withstand loads of power you can use lacquer as well.

I too believe it is best for copper to have contact with the bolt for the best coupling and highest effect on inductance. It is best tho to use a Fem software to determine position, and physical dimensions of the structure.

[Frank40]

I just realised that is might be a life long project for my :-)

I have some questions regarding induction in the coil and the placement of the Faraday ring(s). In the paper by Ahmet Feyz Pirimoglu it is stated that you can use more than one ring so I am looking in to doing just that.

I am trying to make a coil former with a build in Faraday ring. The former is made from tree layers, first layer is a 10 micron alum. Foil with 2 winding... 2th layer is a one layer paper and the 3th. Layger is 2 wingding of 25g/M2 fibreglass, this is all hold together with epoxy resin. This will give a width of 0.2-0.25mm.

Now for the questions:

Hentai, I don't understand the placement of your faraday ring, I would think it has more effect if it was closer to the coil... But I could be wrong. Normally it is placed at the center pole going in to motor itself.

Did you try to do some simulations with more than one ring.

I think a overhung voice coil better in respect to inducting than a underhung, any thoughts on that.

PS. I will post some pic's of the voice coil former if it works out.. and when it is dry.

[Hentai]

Hi Frank,

I have tested with shorting ring inside the gap but because the copper material had to be thin in order to fit the gap it wasnt as effective as a thick ring placed just below the gap. The electrical resistance of the ring is much more important to me than placement. If you attach it to the central pole piece the coupling is pretty good.

Sorry for image quality, im not good at taking pics:


Overhung yes has lower inductance but first i wanted the lower distortion of underhung, second if you make the cone light enough (you have) than inductance isnt such a burden.

Personally i think you should drop the idea of using shorting ring in voice coil. It wont be effective being thin and aluminum. It will add to mass and will interfere with damping. Using a copper or silver ring attached to the central pole piece as thick as possible is best imho. Also designing the voicecoil itself in a good way to reduce inductance. as small a diameter as possible, as high a height as possible things like this.

[Frank40]

Thanks for your replay Hentai, I se what you mean. Well I guess I have to do some more experiments. Take care.

[Frank40]

Hi

Just some note on what I learned. Depron is to soft a material to convert energy from the voice coil to the membrane at higher frequencies , it will require some other material that are very stiff.

I did a new membrane with 4 layers of 25g/M2 fibre glass, it weight 1.9 g for the membrane alone.
I used a voice coil from a Monarco SPH 170C. The voice coil was glued to the membrane using 5 min. epoxy glue.

This relay works, it sound like a full range now, I compared it to my F200A and the new one sounds like it has more dynamic in the top. This might be the one that I keep, but I got a few ideas I need to try.

Any progress with your project?

Here is some pic's:

[Zen Mod]

with that big fat roll of rubber , you'll not get far

for FR delicacy l, you need more delicate surround

I know squat about speakers construction , but that I know

[Frank40]

Hi, Zen Mod

You have to explain why you don't think this works, the high frequency respond is not related to the surroundings. It is more to do with how the transition between voice coil and the membrane and the area around the to.