Circular ribbon microphone capsule

[k brown]

The disc ribbon shown in the OP has nothing whatever in common with any dynamic mic.

The Fostex M88RP (and related models) came the closest to a disc shaped ribbon mic, but it sort of stretched the definition of 'ribbon' - it was kind of it's own thing.

https://www.coutant.org/m88rp/index.htmlhttps://gearspace.com/board/studio-...mics.html?highlight=fostex+m88rp#post15809869

 

[MagnetoSound]

When is a ribbon not a ribbon?

I can’t believe you peeps have indulged this clown. Is this what GDIY has become? Please …

Lets cut the crap and have a great new year.

 

[Arbolito]

To make a good and efficient ribbon motor we have to observe a few conditions:

1. In the air gap we need to maintain a strong, efficient, and uniform flux, so the magnets should be in quite a close proximity and in parallel to each other. We don't want to place them too close, as then the modern Neodymium magnets will saturate. On the other hand, with distance we loose the filed considerably.
2. Ribbon should be stable, with minimum torsion movements. In general, the best ribbon shape to get a good stability and efficiency (along with low impedance) is rectangular.
3. For a good top end response the front to back distances should be minimal (I posted on this some time ago in depth).
4. Low impedance (DCR).

Let's see what happens if we make proposed circled shape:

1. The rule of the field is 2:4, IOW, if we increase the distance in twice, the filed will decrease 4 times. The optimal distance is about .200"--.250" depending on the magnet size. What happens in the round one--the field in the farthest points will be very weak, producing almost no signal. Also, this is providing you will be able to find the magnets of that shape magnetized in a correct plane.

2. Any 'flaps' will increase mass (without actual reducing DCR) and torsion instability, which results in resonances and all kinds of distortions. This is besides obvious fact the DCR will be weird.

3. The round shape introduces considerable front to back distances. Say 1" round will translate into some 1.750" front to back (including magnets), which translates into -3dB @ 7.7kHz.

That is how the ribbons came to a present (rectangular) form when you optimize each of those parameters and put into a system all together. If you are on the budget I'd definitely suggest to go conventional way in this case.

Best, M

P.S. Somebody posted earlier--against of our intuition the top end is not affected by ribbon mass.

Thank you Marik for the extremely useful insights. I'll definitely take them into account when experimenting with the ribbon shape. I decided to go for a bundle of different shapes, and will make frequency response comparisons between different motor shapes.

 

[Arbolito]

When is a ribbon not a ribbon?

I can’t believe you peeps have indulged this clown. Is this what GDIY has become? Please …

Lets cut the crap and have a great new year.

Bandaids should be band shaped always then, and not circles. And microphones should be noisy, and french horns should be made in France

 

[MagnetoSound]

Bandaids should be band shaped always then, and not circles. And microphones should be noisy, and french horns should be made in France

 

[Barry Hufker]

Arbolito,

As you well know, innovation comes by thinking differently and "wondering if..." I encourage you to continue to do so. There is wisdom and knowledge here and I'm glad you're willing to listen to it, and am very glad it's being offered by knowledgeable, generous people. I'm terribly disappointed in those who denigrate a search for something better and choose to ridicule it. I think it's the worst aspect of this, or any, forum. Thank goodness they are few.

 

[abbey road d enfer]

My understanding of circular capsules as compared to rectangular one(Pearl, Milab) is the uniformity in horizontal and vertical polar response.

That is true, however the circular shape is not compatible with the mechanical necessities of a ribbon mic, like how to suspend a circular "ribbon", how to connect it, how to ensure optimized magntic flux lines.
For similar reasons, a "ribbon" condenser mic seems very unlikely.

 

[k brown]

When is a ribbon not a ribbon?

I can’t believe you peeps have indulged this clown. Is this what GDIY has become? Please …

Lets cut the crap and have a great new year.

It'a quite difficult to determine in an online forum if someone is asking an 'outside the box' question out of innocent ignorance/desire to learn, or because thay are a 'clown'.

The mods seem to understand that the better part of valor is to assume the former rather than the latter.

 

[abbey road d enfer]

When is a ribbon not a ribbon?

I can’t believe you peeps have indulged this clown. Is this what GDIY has become? Please …

Lets cut the crap and have a great new year.

Too much food, indigestion, sour stomach?
Relax...

...and behave.

 

[MagnetoSound]

Yeah, a little too much wine. It’s not my usual MO. I apologise without reservation.

As microphones go, the ribbon principle as it exists is just about as perfect as it can be. Reinventing the wheel is a fine idea, as long as you have good reason. I could not see any justification for two pages of exposition. I have nothing against a healthy curiosity, of course, and I applaud any attempt to explore improvement. That said, there is a reason the wheel is round and the ribbon is … well, a ribbon.

It was not my intention to cause unnecessary offence. I honestly thought the OP was on an elaborate wind up. Mea culpa.

 

[frans]

Unusual ribbon mics: in the book about the life of Alan Blumlein (the inventor of many things in audio and radar) there is the picture of a peculiar ribbon mic, it shows the motor without the body so you can have a good look. It's not like others and when you see it you understand why it will work. The ribbon is a strip, the magnet assembly like nothing else you've seen. I'd show the picture but i gave the book to a friend. Keep in mind Mr. Blumlein was a very clever man and that included finding solutions that nobody else was clever enough to come up with. So one mans stupid question could be another mans start of a new invention in the end.

 

[S.Samuelsson]

Hi.

Do you think this would work?

I'm also going to vote: No, it won't work.

That design You're proposing offers zero advantage and maximum disadvantage over the "normal" ribbon motor construction.
Absolutely nothing will obviously prevent You from trying though.

Unlike a super cheap and crude DIY ribbon mic constructed from 2 bar magnets and a corrugated strip of a kitchen foil (reverse-)connected to a ~9~12V mains transformer for impedance matching, it's quite possible that Your design won't work at all.
The reasons for that have been adressed multiple times already, so I won't be repeating them.
The basic ribbon mic theory is very simple, I do encourage You to study it.

While a ribbon mic is by far the easiest -and therefore the most popular- mic design to DIY from scratch, it is probably also the most difficult to get sounding as good and/or as consistent as possible.
For example, that "super cheap DIY ribbon mic" I mentioned earlier, will be guaranteed to sound quite pequliar (and no two will sound alike) because of the way too thick ribbon and the less than ideal transformer, but it will be usable as a Lo-Fi or effect mic when encased, shielded, etc.
Or simply just as a proof of consept.
Not bad IMO for 5~10 €/£/$ of parts and ~1 hour of tinkering.
That kind of a bare bones design obviously leaves a lot of room for improvement also .

Regards,
Sam

 

[shabtek]

while the round foil shape with 2 diametrically opposed tabs shape does not seem to have merit, the curved magnet poles raises the question: how are the magnetic fields oriented? there may be opportunity for novel configuration of the magnets to achieve a more desirable acoustic environment...we would need to be able to visualize where the flux i concentrated.
the curved shape reminds me of the horseshoe magnet used in 44 etc.

 

[gyraf]

...re. the horisontal/lateral sensitivity question: ..could we then do a cross-ribbon in stead - like two ribbons, joined at centre - now four magnets, one in each quadrant? ..would require some intricate pole-pieces to get magnetic fields distributed to the right place&side of the ribbon(s).

 

[Marik]

...re. the horisontal/lateral sensitivity question: ..could we then do a cross-ribbon in stead - like two ribbons, joined at centre - now four magnets, one in each quadrant? ..would require some intricate pole-pieces to get magnetic fields distributed to the right place&side of the ribbon(s).

IMO, ribbon mic has a perfect directivity in all planes as it is—very wide horizontally and narrow vertically, which greatly helps to avoid floor and ceiling reflections. The ribbon cross will considerably complicate the construction, which probably won’t be justified.

Best, M

 

[abbey road d enfer]

IMO, ribbon mic has a perfect directivity in all planes as it is—very wide vertically and narrow horizontally

Isn't it the contrary?
After all, it depends how you orient the mic

 

[Marik]

Isn't it the contrary?
After all, it depends how you orient the mic

Was thinking one thing, but writing another edited the post

 

[gyraf]

IMO, ribbon mic has a perfect directivity in all planes as it is—very wide horizontally and narrow vertically, which greatly helps to avoid floor and ceiling reflections. The ribbon cross will considerably complicate the construction, which probably won’t be justified.

Best, M

I hear ya' - but I have this feeling that it could be interesting to have both, then matrix them +/- in the step-up transformers

 

[abbey road d enfer]

Was thinking one thing, but writing another edited the post

It happens quite often, confusing directivity index and pattern angle.
Same confusion with load. A heavy load is a small impedance, light load is high impedance.

 

[s wave]

Aluminum oxide plates have been made less than 1 micron. Obviously aluminum oxide is not good for a ribbon motor. But what if it was 'sputtered' with silver or gold or something?

Penn Researchers Make Thinnest Plates That Can Be Picked Up by Hand​

back in 2015. Just an OTB idea.