Ribbon mic magnet orientation
« on: January 10, 2019, 11:13:00 PM »
I'm thinking about making a ribbon mic from scratch. I would like to confirm that the correct orientation of the magnets should be with respect to the ribbon. There are four general orientations: (A) The planes of the active magnet surfaces are parallel to the ribbon surface and with the same polarity; (B) the planes are parallel with opposite polarity; (C) the planes are orthogonal to the surface of the ribbon with the same polarity (i.e. S-to-N, pulling each other together); (D) the planes are orthogonal to the surface with the opposite polarity (S-to-S, pushing against each other).

(By the way, N=North, S=South)

A:

B:

C:

D:

Which is right?

Thank you!


L´Andratté

Re: Ribbon mic magnet orientation
« Reply #1 on: January 11, 2019, 03:29:53 AM »
http://bfy.tw/Lji8
First hit  ;)
Strictly amateur since 1973...

Re: Ribbon mic magnet orientation
« Reply #2 on: January 11, 2019, 09:06:24 AM »
L´Andratté, I like a sarcastic response as much as the next guy, but I'm afraid that in this case it's not just a matter of "Googling" the answer. I should have clarified: I have spent a good bit of time doing some research, but have found answers to be insufficient and in  many cases contradictory.

For example, the Wikipedia page on ribbon mics (https://en.wikipedia.org/wiki/Ribbon_microphone) shows what looks a lot like my version "B".  But some of the DIY pages (e.g. http://www.diyaudiocomponents.com/diy-ribbon-mic-magnets) show what looks like my "C".  And many of the potentially good sources (https://www.mymorninglight.org/ham/ribbon.htm) are full of dead links. Finally, many vintage mics (which are well documented) use horseshoe-style magnets which are not applicable to my design.

THAT is why I've come to this forum for help. I would like to hear from folks directly who have actually done a project like this.

So, if anyone has some thoughts,  they would be appreciated!

L´Andratté

Re: Ribbon mic magnet orientation
« Reply #3 on: January 11, 2019, 12:35:26 PM »
Hey, but that could have been some good information to include in your first post...

Btw. did you read first entry I was hinting at? It explains things quite good.
Quote
For ribbon microphone applications we need both magnets to face the ribbon with surfaces that carry the opposite poles, so the magnetization direction with poles on largest surfaces is exactly what we need.
Page is by Arthur Fischer, he is reliable. Makes ribbon mic kits which everybody (incl. me) loves!
Strictly amateur since 1973...

cyrano

Re: Ribbon mic magnet orientation
« Reply #4 on: January 11, 2019, 04:31:35 PM »
Btw. did you read first entry I was hinting at? It explains things quite good.Page is by Arthur Fischer, he is reliable. Makes ribbon mic kits which everybody (incl. me) loves!

You can't rely on everyone getting the same link on top, especially since you didn't supply the search phrase.
Why is it people love to believe and hate to know?

L´Andratté

Re: Ribbon mic magnet orientation
« Reply #5 on: January 11, 2019, 04:40:18 PM »
You can't rely on everyone getting the same link on top, especially since you didn't supply the search phrase.

My bad! It´s here
http://www.diyaudiocomponents.com/diy-ribbon-mic-magnets
Strictly amateur since 1973...

cyrano

Re: Ribbon mic magnet orientation
« Reply #6 on: January 11, 2019, 05:27:05 PM »
Which tells us pic C is right...
Why is it people love to believe and hate to know?

Re: Ribbon mic magnet orientation
« Reply #7 on: January 11, 2019, 11:08:21 PM »
I'm thinking "C" as well. In that orientation, intuitively, there is the strongest, coherent straight-line flux between the two magnets. The ribbon has the "cut" the flux to induce a voltage, so the flux has to be perpendicular to the movement of the ribbon. Thanks for the help!


 

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