DIY ribbon drivers using Neudynium magnets? - diyAudio
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Old 12th May 2003, 05:12 AM   #1
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Default DIY ribbon drivers using Neudynium magnets?

Hi all of you.

I have been offered some surplus neodynium magnets and got the idea to use them for making a pair of ribbon drivers. The magnets are WERRY powerfull. This should give a driver with a high sensitivity. Have anny of you heard about others using these magnets for DIY?

About making the ribbon foil with the conductive foil, where can i find information about this?

Thanks for helping out.


Peter Jensen
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Old 12th May 2003, 06:04 AM   #2
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Default Re: DIY ribbon drivers using Neudynium magnets?

One of my audio buddies has built mid & tweeter ribbons... he couldn't afford Neo magnets -- if you have enuff of them it should be doable -- because of the pull it can be tricky getting the magnets into position -- watch your fingers.

dave
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Old 12th May 2003, 06:06 AM   #3
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Actually I'm planning to try my hand at building a long ribbon driver. The ribbon fabrication and magnet placement is fairly easy. But for a short ribbon (like the stage accompany, raven, etc) have short ribbons (for good vertical dispersion) and thus the ribbon is very low impedance and needs a matching transformer.

My idea is to make a much longer ribbon and pick the ribbon thickness and width to get me to a reasonable (4 ohms or so) impedance without a matching transformer. I haven't done the calculations yet, and I'm hoping that I don't need a 30 foot high ribbon.

Sheldon
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Old 12th May 2003, 06:16 AM   #4
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Quote:
Originally posted by stokessd
I haven't done the calculations yet, and I'm hoping that I don't need a 30 foot high ribbon.
My buddies midrange ribbon is 5 or 6' long and he still needs a matching trafo...

dave
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Old 12th May 2003, 07:24 AM   #5
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Default Hi again

Thanks for replying.

I know of the impedance problems with ribbons. I was thinking of making a line source combined with a dipol sub. Using these magnets i think it could be made using a quite wide midrange ribbon 4-8 cm combined with a more narrow 1 cm tribble ribbon in the same gap. (X-over 5khz or so) This would not be posible using standard magnets (to low a field when taking the magnets to far apart = low sensitivity), but it might be posible using neodynium ones. The reason why i would like a wide midrange is to improve the low freq respons of the system. X-over to the bass should be about 100 Hz or so. I have made ribbons before (La folia) and i remember thet the hard part was to make a relative wide ribbon that had a good tribble respons. Making a light narrow tribble ribbon with a good tribble respond is not hard.

Problems. Would it be posible to mount a tribble ribbon in front of a midrange ribbon in the samme magnet gap? An other option would be to mount the trible ribbon beside the midrange ribbon. Maybe in a M - T - M configuration with a pair of midrange ribbons beside a tribble ribbon.

About mounting the magnets are surplus mountes on a steel bracket with holes, so they are easy to mount.

What do you think?


Peter
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Old 12th May 2003, 07:26 AM   #6
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Default Picture

Hi again

Here is a picture of the magnet type.

Peter
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Old 12th May 2003, 07:38 AM   #7
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That looks like the magnet from a hard drive.

I just read some DIY ribbon stuff on www.snippets.org. John R. Whittaker's "cautionary tale" didn't motivate me. Sounded like a disappointing experience.

When I get home I'm going to check out May2001 of AudioXpress which had a DIY ribbon article by Justus Verhagen.
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Old 12th May 2003, 07:24 PM   #8
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It takes a remarkable amount of B and H fill a 3/4" gap at 2Tesla. Not to mention a whole mess of steel...

http://www.soundimage.ishoejby.dk/Di...col/Ribbon.htm

Those ESG ribbons are pretty reasonably priced.

happy experimenting, John
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Old 15th May 2003, 12:57 PM   #9
Bill F. is offline Bill F.  United States
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Here's some *BIG* Nd magnets I saw recently. A great way to hurt yourself quick if you're not careful. 2 little 1.25"x0.5"x0.15" Nd35s once gave me a blood blister. I would think through every movement before I picked up one of these brutes.

4x5 square N38

4" dia. N38
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Old 15th May 2003, 04:50 PM   #10
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Default Nd

Hi again

These are BIG , but also werry expensive . The surplus ones I have considered cost a small fraction of the price of these . I am thinking of using a lot of them to make somthing like a 150 Cm line source . This will take a LOT of magnets so they need to be cheap. Still using cheap surplus Nd magnets will give more power then stardard megnets normally used for making ribbons. I will be making some experiments in the future with these. I will let you know.


Peter Jensen
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