Old ribbon mic threads, anyone have them archived?
- Thread starter smilinfu
- Start date
Help Support GroupDIY Audio Forum:
Here is a very crude drawing of what I am doing.
http://www.home.earthlink.net/~smilinfu/
Marik I am using sign makers aluminum leaf, what you would use to make face silver to furniture of whatnot, I got it from Pearl Paint so I don't know much about it. I think the gears I am using to coregate it have 14 ridges per inch. I am looking forward to trying this again with the Lundahls, wish I had noticed them earlier. I will probably be a week before I get chance to try it with the magnets in a different configuration.
Rafafredd I can take up to 7 mb, shouldn?t be a problem. Thanks for being willing to send it. If there is a problem do not worry about it.
http://www.home.earthlink.net/~smilinfu/
Marik I am using sign makers aluminum leaf, what you would use to make face silver to furniture of whatnot, I got it from Pearl Paint so I don't know much about it. I think the gears I am using to coregate it have 14 ridges per inch. I am looking forward to trying this again with the Lundahls, wish I had noticed them earlier. I will probably be a week before I get chance to try it with the magnets in a different configuration.
Rafafredd I can take up to 7 mb, shouldn?t be a problem. Thanks for being willing to send it. If there is a problem do not worry about it.
Marik
Well-known member
Smilinfu,
I am still uncertain about your whole arrngement, as for frame, its dimentions, position in relationship to the magnets. Is soundwave coming to the rear of the ribbon freely? How do you clamp the ribbon? There should be a very good contact.
I am still uncertain about your whole arrngement, as for frame, its dimentions, position in relationship to the magnets. Is soundwave coming to the rear of the ribbon freely? How do you clamp the ribbon? There should be a very good contact.
Sorry, I am not so good at explaining things :?, even through pictures(damn the effects of no sleep). It is totaly simple, just not coming out of my brain that way anymore. I will see if I can get my hands on a camera and take pictures of the elements. I am in pritty continuous rehersals through to the weekend.
Svart
Well-known member
since we are on the topic, anybody try to cut magnets? what would you use a diamond, water cooled tile saw?
SilverhammerNZ
Well-known member
Badger/Marik,
If you have those missing pages I would be very pleased to see them, I've lived with that article for years without those pages.
Let me know here asap.
Thanks.
Larry
If you have those missing pages I would be very pleased to see them, I've lived with that article for years without those pages.
Let me know here asap.
Thanks.
Larry
rafafredd
Well-known member
You should try Yahoo email box for free. They affer 100Mb now.
My ribbon mic folder has 30Mb of info...
Marik
Well-known member
[quote author="Svart"]since we are on the topic, anybody try to cut magnets? what would you use a diamond, water cooled tile saw?[/quote]
If you are talking about Neodymiums the answer is no. I was talking about it to a magnet manufacturer. These magnets are pressed from a powder and are very brittle--thats the reason why they always have some kind of coating--nickel, gold, epoxy. Another thing--they are very sensitive to heating and ones heated, lose magnetic properties. I tried to drill it--very hard stuff--could not go through. It is a better idea to find the right one. Many companies offer custom sizes.
Larry,
I will post it as soon as Andy sends it to me.
And here is my latest ribbon I finished last night:
If you are talking about Neodymiums the answer is no. I was talking about it to a magnet manufacturer. These magnets are pressed from a powder and are very brittle--thats the reason why they always have some kind of coating--nickel, gold, epoxy. Another thing--they are very sensitive to heating and ones heated, lose magnetic properties. I tried to drill it--very hard stuff--could not go through. It is a better idea to find the right one. Many companies offer custom sizes.
Larry,
I will post it as soon as Andy sends it to me.
And here is my latest ribbon I finished last night:
SilverhammerNZ
Well-known member
Nice work, Marik. What foil are you using?
And thanks re missing pages, I'll look forward to seeing them up here.
larry
And thanks re missing pages, I'll look forward to seeing them up here.
larry
rafafredd
Well-known member
from wondermagnet:
Just make sure you are beying carefull.
Marik
Well-known member
I got the missing pages and will post them as soon as I convert them from *.max. Thank you Andy!
For this mic I used about 3um foil from an old Illinois paper-in-oil cap. The magnets are 1" long, so the sensitivity is not as good as longer and thinner ribbons. Also, because of thicker and shorter ribbon there is a very pronaunced bump around 200-300Hz. I will try some different silks to dampen it. Also, a thinner foil should help.
For this mic I used about 3um foil from an old Illinois paper-in-oil cap. The magnets are 1" long, so the sensitivity is not as good as longer and thinner ribbons. Also, because of thicker and shorter ribbon there is a very pronaunced bump around 200-300Hz. I will try some different silks to dampen it. Also, a thinner foil should help.
SilverhammerNZ
Well-known member
I have been recently trying some 2.5 micron foil but find it is not as good as my very thin aluminium leaf although much easier to work with. It could be the matching to the transformer but I am not getting the top end I get with leaf. Thickness is not upposed to effect frequency but something is in this experiment.
Larry
Larry
> here is my latest ribbon I finished last night:
Are the cross-pieces iron? The magnetic path should be "closed" except the gap the ribbon lives in. If the uprights are iron, then just laying a scrap of iron across the two uprights should give more than 6dB more output.
Are the cross-pieces iron? The magnetic path should be "closed" except the gap the ribbon lives in. If the uprights are iron, then just laying a scrap of iron across the two uprights should give more than 6dB more output.
G
Guest
Guest
PRR, by "closed" do you mean a path through the ferous material from pole to pole, like a horse shoe magnet? The ribbon then resides in the gap between poles. That is how I understand the orientation to be, thereby allowing the ribbon to be exposed to a maximum flux density. I hope I don't have this screwed up.
Wow thanks PRR, I have been wondering if the magnets should be somehow connected (don?t know what to call it for magnets). I snapped my ribbon while tinkering again, but can't wait to try your suggestion. Am a little ashamed to post any pictures of my attempts. They look like macaroni glued to construction paper compared to Marik?s
Marik
Well-known member
[quote author="PRR"]> here is my latest ribbon I finished last night:
Are the cross-pieces iron? The magnetic path should be "closed" except the gap the ribbon lives in. If the uprights are iron, then just laying a scrap of iron across the two uprights should give more than 6dB more output.[/quote]
No they are aluminum--I don't have iron of needed thickness at the moment. Then the mount base also should be made out of piece of iron, and used as a return circuit. However, there is one important question.
In theory, it will work as two gaps in series--one where where ribbon placed, and the other going between the other poles. That is like having two resistors in series. It works nicely with weaker magnets.
I made a few experiments with Neodymiums, using 1/4"x1/4" (across) ironm as pole pieces. Closing the path did not have almost any affect on the sensitivity.
The equation for ribbon output shows direct relationship between output and magnetic flux, however in practice it was not so. My speculation is that with very strong magnets there is a point of saturation, where it does not work like theory says, anymore.
Any ideas?
Are the cross-pieces iron? The magnetic path should be "closed" except the gap the ribbon lives in. If the uprights are iron, then just laying a scrap of iron across the two uprights should give more than 6dB more output.[/quote]
No they are aluminum--I don't have iron of needed thickness at the moment. Then the mount base also should be made out of piece of iron, and used as a return circuit. However, there is one important question.
In theory, it will work as two gaps in series--one where where ribbon placed, and the other going between the other poles. That is like having two resistors in series. It works nicely with weaker magnets.
I made a few experiments with Neodymiums, using 1/4"x1/4" (across) ironm as pole pieces. Closing the path did not have almost any affect on the sensitivity.
The equation for ribbon output shows direct relationship between output and magnetic flux, however in practice it was not so. My speculation is that with very strong magnets there is a point of saturation, where it does not work like theory says, anymore.
Any ideas?
Marik
Well-known member
[quote author="SilverhammerNZ"]I have been recently trying some 2.5 micron foil but find it is not as good as my very thin aluminium leaf although much easier to work with. It could be the matching to the transformer but I am not getting the top end I get with leaf. Thickness is not upposed to effect frequency but something is in this experiment.
Larry[/quote]
Larry,
Yes, the thikness should not affect the top end, however, it might affect it indirectly--because of worse damping properties of thicker foil, we have more resonances, including those in HF range, which subjectively heard as "less crispy" and clear.
Larry[/quote]
Larry,
Yes, the thikness should not affect the top end, however, it might affect it indirectly--because of worse damping properties of thicker foil, we have more resonances, including those in HF range, which subjectively heard as "less crispy" and clear.
Hi Marik
Nice Avatar!
It's really interesting to compare your element with the 'originals'. You're looks really well put together. I started a new thread because I thought it would have broad appeal & will document as many as I can get my hands on - certainly tannoy, grampian and reslo mics.
Stewart
Nice Avatar!
It's really interesting to compare your element with the 'originals'. You're looks really well put together. I started a new thread because I thought it would have broad appeal & will document as many as I can get my hands on - certainly tannoy, grampian and reslo mics.
Stewart
Marik
Well-known member
[quote author="zebra50"]Hi Marik
Nice Avatar!
[/quote]
Thanks Stewart,
Yeah, I never had one. Hey Gus, it's time for you to have, as well, don't you think so? Send me a pic and I will host it for you.
Nice Avatar!
[/quote]
Thanks Stewart,
Yeah, I never had one. Hey Gus, it's time for you to have, as well, don't you think so? Send me a pic and I will host it for you.
> In theory, it will work as two gaps in series--one where where ribbon placed, and the other going between the other poles. That is like having two resistors in series.
Yes. Except one of the resistors is VERY big. An inch of air is a lousy magnetic path.
> I don't have iron of needed thickness at the moment
Any hunk of iron, even with bad contact, "should" be better than an inch of air. Got a beer-can opener made of steel? Lay it on the vertical pieces. (Or is all beer pop/screw-top now?)
> My speculation is that with very strong magnets there is a point of saturation
That may be true. Of course it IS true, but with an inch of air in the path.....
The magnet-stuff will saturate, and usually before the steel will. The usual trick for Alnico loudspeakers is to use magnet-area about 3 times bigger than gap-area, and use a tapered iron pole-piece to concentrate the magnet area down to the gap area. (With ceramic-magnet speakers, the magnet area is SO much bigger than the gap area that they just fake a taper with a flat plate and a round slug.) Same thing on older ribbons, the pole pieces taper. To concentrate the flux, but also so the magnet face does not saturate before the iron does.
Of course added pole-pieces usually increase leakage flux, and demand even more magnet area.
Maybe I know a retired hard-drive engineer who will know the flux density at the face of modern high-energy magnets. I know that recent hard drives do not use pole-pieces, the coil is directly between magnets (with a closed iron path around the outside). But hard drive coils are very large area so it would be impractical to get the very high flux we enjoy in loudspeakers. He almost didn't believe me when I said some loudspeakers run 20,000 Gauss in the gap (though 8,000 Gauss is much more common). It may be that these magnets saturate with a few thousand Gauss at the face. And that HD designers can meet their seek-time goals with such "low" flux by over-driving the coil.
Yes. Except one of the resistors is VERY big. An inch of air is a lousy magnetic path.
> I don't have iron of needed thickness at the moment
Any hunk of iron, even with bad contact, "should" be better than an inch of air. Got a beer-can opener made of steel? Lay it on the vertical pieces. (Or is all beer pop/screw-top now?)
> My speculation is that with very strong magnets there is a point of saturation
That may be true. Of course it IS true, but with an inch of air in the path.....
The magnet-stuff will saturate, and usually before the steel will. The usual trick for Alnico loudspeakers is to use magnet-area about 3 times bigger than gap-area, and use a tapered iron pole-piece to concentrate the magnet area down to the gap area. (With ceramic-magnet speakers, the magnet area is SO much bigger than the gap area that they just fake a taper with a flat plate and a round slug.) Same thing on older ribbons, the pole pieces taper. To concentrate the flux, but also so the magnet face does not saturate before the iron does.
Of course added pole-pieces usually increase leakage flux, and demand even more magnet area.
Maybe I know a retired hard-drive engineer who will know the flux density at the face of modern high-energy magnets. I know that recent hard drives do not use pole-pieces, the coil is directly between magnets (with a closed iron path around the outside). But hard drive coils are very large area so it would be impractical to get the very high flux we enjoy in loudspeakers. He almost didn't believe me when I said some loudspeakers run 20,000 Gauss in the gap (though 8,000 Gauss is much more common). It may be that these magnets saturate with a few thousand Gauss at the face. And that HD designers can meet their seek-time goals with such "low" flux by over-driving the coil.
