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Thread: My new ribbon hybrid mic

  1. #11
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    Arcanemethodes,

    <It will get a lot stronger with a return path.....
    It need not be very thick at all to make a big difference.>

    In theory it sounds right. The magnetic gauss is a directly proprtional to the mic sensitivity. Today I finished a new mic found in the picture below. I made it using neodymium magnets in return path between iron bars. And you want to know something? It did not make much noticable difference. These neodymium magnets are amazingly strong. How many times I pinched my fingers to blood... It is probably my speculation, but I suspect that there is a saturation point where the gauss is no longer so important. Remember Lowther speakers--neodymium magnets, air gap brought to the minimum, but still, sensitivity is around 103db--many vintage alnico magnet speakers have that.
    Actually, now I think I should have built it without these iron bars for sake of HF response. BTW, the high sensitivity besides of strong magnets is due to very light ribbon.

    Yeah, it is already my sixth ribbon mic I built so far.
    Attached Thumbnails Attached Thumbnails newribbon-jpg  
    Last edited by Marik; 03-01-2004 at 01:42.

  2. #12
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    Originally posted by Marik
    Here is a close up of the ribbon capsule. The ribbon itself is made out of 1.5 micron aluminum foil.
    Wow! Great job (as usual)! Where did you end up getting the 1.5 micron stuff?

    I thought about getting one of those old busted EV ribbons and use the case for the ribbon in my Oktava. Last time I checked, one that didn't even work went on eBay for $125-$150. Where did you get yours?

  3. #13
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    Originally posted by Marik
    Arcanemethodes,

    <It will get a lot stronger with a return path.....
    It need not be very thick at all to make a big difference.>

    In theory it sounds right. The magnetic gauss is a directly proprtional to the mic sensitivity. Today I finished a new mic found in the picture below. I made it using neodymium magnets in return path between iron bars. And you want to know something? It did not make much noticable difference.
    Marik, did you compare the sensitivity of the assembly you show with and without the return path? You are right that theory predicts a big difference and I can't think of a reason why theory would fail in this case. I'd sure like to understand, though.

    To say it isn't different is to say that you can increase the width of the gap without any reduction in field strength and I don't understand a mechanism that would allow for that behavior.

    I'm fairly new around here, have you explained before your source and method for making the ribbons?


    Thanks,

    Bob

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    <Marik, did you compare the sensitivity of the assembly you show with and without the return path?>

    Naturlicht!
    Yep, when once I used ceramics, it made a lot of difference, now--nope.

    <To say it isn't different is to say that you can increase the width of the gap without any reduction in field strength and I don't understand a mechanism that would allow for that behavior.>

    The gap width increase is square proportional to magnetic guass. That is probably the most I can say in this case. We need somebody here who understands in magnetism.

    <Where did you end up getting the 1.5 micron stuff?
    I thought about getting one of those old busted EV ribbons and use the case for the ribbon in my Oktava. Last time I checked, one that didn't even work went on eBay for $125-$150. Where did you get yours?>

    Stephen Sank kindly sent me a little sheet of original RCA stuff. I have left for probably 2-3 more ribbons. I found a source in UK for 2.5 and even 0.6 micron. It is expensive to buy only one, and price break is for little quantities. If somebody wants to join me to buy, please let me know. Before I was using foil from old paper in oil caps. The thinnest I could find was 2.5 micron, which is still good.

    Yeah Flatpicker, you bet. I got EV busted on ebay a couple years ago. It was around $120, I think.

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    How are you guys measuring the micron film... are you using a precision micrometer, and if so, which one? Thanks

    PS... great thread.
    One of the things I like the most about hr.com is reading what everyday people like you and I have experienced with products as opposed to reading what the manufacturers want us to read about their products.

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    <DJL How are you guys measuring the micron film... are you using a precision micrometer, and if so, which one? Thanks>

    I am using usual micrometer, but stack 10 layers of foil and then divide the measurement by this number. I saw digital micrometers in jewelry supply stores with 1 micron resolution--pretty expensive stuff. You can also find the thickness of the aluminum foil from it's mass.

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    Wow, Marik, you continue to amaze me! A while back I tried to build a ribbon element, but it was no more than a proof of principle. You could hear the rattle, when the ribbon moved. But then again I just used ordinary aluminum foil found in the kitchen and a couple of reed magnets I bought to buid guitar pickups. The transformer was ultra-cheapo too.

    I'm really amazed you managed to build a real usable ribbon microphone from scratch.

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    Originally posted by Marik
    <DJL How are you guys measuring the micron film... are you using a precision micrometer, and if so, which one? Thanks>

    I am using usual micrometer, but stack 10 layers of foil and then divide the measurement by this number. I saw digital micrometers in jewelry supply stores with 1 micron resolution--pretty expensive stuff. You can also find the thickness of the aluminum foil from it's mass.
    Thank you Marik.
    One of the things I like the most about hr.com is reading what everyday people like you and I have experienced with products as opposed to reading what the manufacturers want us to read about their products.

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