A DIY Ribbon Speaker of a different Kind

[Few]

Henjo: Nice job! It looks very well put together. The voice coils came out very nicely. I'd love to see some frequency response measurements.

How readily available (and costly) is ferrofluid? That seems like it would really help keep the voice coil from rubbing on the magnets. I don't know if it would pool at the bottom of the gap under the influence of gravity, though.

Few

[tinitus]

I dont think theres any issue with having a magnet gap like say 5mm, with those strong neo magnets available
The ones I have been looking at lifts 60pound EACH, and there may be like 12 of them on each side of the gap, a total of 24 magnet on each speaker
24 magnet would lift close to 1500pounds

But to assemble it all without getting hurt badly could be a delicate operation
But I have plans fore that
But it could be exstremely dangerous if handeled carelessly

[koldby]

Very nice!!
How did you roll those very fine coils?
Keep up the good work and please keep us updated on your progress.
Anybody else who did a prototype?
Koldby

[Henjo Edel]

@ Koldby

Coils are hand wounded.
Every turn was glued on the paper with cyanoacrylate.
3 to 4 hours work, and a lot of patience

Here's a closer picture, just before sticking the two pieces of paper together.
Center distance of the coil 20mm, length 300mm, turns 16.

Henjo

[tinitus]

Fore what its worth, here the principle of "motor" design

One huge advantage is that you can use very strong magnets, without having any problems to keep them in place

Another big advantage is the narrow magnet gap, over a ribbons and planars
And you get two gaps with opposite polarisation, perfect fore the "voicecoil" having "two directions"
And you can make it underhung

And not to forget all the other stuff like sensitivity, huge bandwith, cheap materials, use of solid copper wire, etc
And probably close to indestructable

Henjo, how do you rate sensitivity of your proto ?

[mightym]

Originally Posted by tinitus

I think the original Rubanoide has a thread to prevent sagging
I consider to use 2 strings in a "V"..."a henfoot", like men of the sea call it

I was thinking along similar lines. I have also been considering some silk cloth, doped like a spider, cut into a triangle, and corrugated while wet to allow the voice coil to run linear while the " suspension " stretches a controlled amount. Mounting one top and bottom.

John

BTW Henjo, Excellent looking work. Just how heavy is that paper? I've been considering Kraft paper, with a doping of Dammar lacquer.

[tinitus]

I dont think they are supposed to move that much

I certainly intend to use other means fore the dipole and BSC compensation

"Rubbing voicecoil" may not be the real issue
Im more concerned about instability causing small ressonaces
You might call it non linear motion
But the less it moves, the less to be concerned about
At least I think so, but actually not sure about it

[Henjo Edel]

Originally Posted by mightym

BTW Henjo, Excellent looking work. Just how heavy is that paper? I've been considering Kraft paper, with a doping of Dammar lacquer.

The paper is 200 gr/m2.
I don't worry about sagging. I thought it was used to center the paper between the magnets. Because they are also at the lower end.

Henjo

[Joachim Gerhard]

Great and simple design ! i would love to see some measurements but radiation pattern may make that a bit complicated. Important is that it sounds good.

[Henjo Edel]

Originally Posted by tinitus

Henjo, how do you rate sensitivity of your proto ?

Here is a quick and dirty measurement. Uncalibrated microphone.

Graph isn't labeled. Steps of about 15 deg.
Yellow = 0 deg.
Green (light) = 90 deg

BTW magnets are ferrite class Y30BH.

Henjo