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The DIY Ribbon Velocity Microphone, a home project

How I did it.

Yikes.  This may be tough.

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Tools and Materials

O.K.  I didn't take any pictures of the process, mainly because I couldn't find my crappy digital camera.  You'll just have to envision it.  Or email me for more precise explainations.

1)  I knew I was going nowhere without the two most important parts.  I had to find the magnets and the ribbon material.    I actually had the magnets.  they were a part of some newer Fender single coil pickups.  They are ceramic, so not that powerful, but they are the most powerful ceramics I have ever run across. 
     The ribbon material was a bit tougher.  Eventually, I ran across Mr. Kilips site on the internet (see my links), and he suggested using some different materials.  As it turns out, Hobby Lobby carries a material known as Silver Leaf, which is pure silver sheets that are about 3-5 microns thick.  They come in a package of 25,  5 inch by 5 inch sheets for $6.99.  It's hard to deal with because it's extremely thin, but it is necessary to have such thin material to have maximum sensitivity and decent output.
 
2)  Next, I decided on a base material, or the piece of the mic that all the other parts would be supported by.  My first prototype used a lightswitch plate or cover, modified to accomodate a two inch ribbon in the hole in the middle and the two magnets on each side.  The Dremel was priceless.
 
3)  The ends of the ribbon had to be clamped somehow, so I made some clamps out of 1/8th inch plexiglas and small screws. 
 
4)  I epoxyed the magnets in place with a perfectly sized spacer to ensure proper spacing for the ribbon to fit into.
 
 
 
 
 
 
 
 
 
 
 
Please see #5 under the diagram->>>>
 
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TIP:
 
     If you do a lot of constructing of things such as this, you might want to invest in a measurement caliper and/or micrometer gauges.  They allow you to measure something to within a thousandth of an inch, and is handy for things like the gap in the magnets, guitar string thickness, etc.  They are quite expensive and can easily run you over 100 bucks for a single tool, but you can find used ones in pawn shops, flea markets, and a few other places.  I bought mine for 15 dollars a few years ago, and it has been priceless ever since.  These calipers replaced some very aging micrometers I had, and were well worth the money.

A list of materials I used:
 
Magnets 2" by 1/4" by 1/4" (variable)
     (larger and stronger is better)
base material to hold magnet and ribbon assembly
     (needs to be very flat and reasonably rigid)
a sheet of 1/8" plexiglass
     (doesn't have to be too big)
an assortment of small screws
a 4" PVC 1/4" turn drain pipe
2 stove-top pot "splatter guards" from Wal-Mart
A whole bunch of brick-bands
     (You can find these at most construction sites)
some other odds and ends I'll try and address later
 
And the biggie, a Jensen JT-346-AX audio transformer
 
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This diagram is also included on the next page.  It gives you the general idea of how a ribbon mic put together, but on the next page, it is supplemented with other diagrams and photos. 
Please see the related note on the next page, refering to the pin configuration

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5)  I used adhesive-backed copper shielding for the contacts in both clamps. 
 
6)  The ribbon forming.
     I suggest you try Larry Killip's suggestion on his webpage.  http://www.lkmusic.co.nz/ribbonfix.htm  It must be corrugated to allow for tension without being tight (if that makes sense to you).  Try his technique first, and be prepared to fail quite a few times before you get it right.  After you learn how YOU do it best, it is easy after that. There really is no wrong answers, just what is right for you to make it work!
     I have developed my own techniques that I will share with you if you ask.  But here are some tips
     1)  wash EVERYTHING with isopropyl alcohol before you start the ribbon cutting and forming.  Your hands, you table surface, ruler, everything.  You don't want any grease on anything, or the ribbon will stick to it and won't come off without leaving a good portion of the ribbon behind.  If you think it's clean, clean it again.
     2)  Static and the ribbon do not mix.  try to take the static charge off of everything as much as possible.
     3)  I find it better to work with the ribbon when it is DRY.  Larry suggests using mineral oil or alcohol while working with it, but it seems to be much easier for me dry, and also, the ribbon holds its corrugation much more without the weight of the fluid.
     4)  Use a piece of plexiglas as your straight edge for cutting the ribbon.  This allows you to pre-measure the ribbon width on the plexiglas and lay it down on the sheet of silverleaf.  This lets you see the ribbon and its reaction to the cutting, pressure, and also lets you keep tabs on the size of the ribbon slice.  If both the plexiglass and the surface are very clean and static-free, you can easily readjust the ribbon material to the right dimension (which you can't do if your straight edge is opaque).
 
     5)  If you can't hold your breath while you are working with the ribbon, go to a hardware store and buy some cheap tube to run out of your mouth and over your shoulder.  It worked for me until I got used to being aware of where every breath came from and was going while I was working with the silver leaf.
     6)  Let the ribbon go where it wants to go.  The ribbon is so thin and light that it will want to fly with the slightest breeze.  don't fight it or it will rip.  If everything is clean and static free, it won't stick to anything, so it won't hurt to let it go a little wild and where it wants to.
 
7)  I inserted the ribbon into the gap of the magnets and positioned it in the clamps.  This is a little more difficult than it sounds, because the width of the ribbon and the width of the magnet gap are pretty close. Getting the ribbon to be as close to both sides of the gap without touching is a pretty tough job if you are as precise as I was, but being super-precise is not absolutely necessary.  In my experience, though, it can make a difference, especially in output.   Also, the ribbon can't be twisting or sagging, and you have to be careful not to pull out the corrugations.  The ribbon also must be pulled to a fair tension, but not tight enough to pull out the folds.  The tension has to be tight enough for the ribbon to hold itself up without sagging.
     Another tip.  Take a Volt/Ohm meter to check to see if the ribbon is touching the magnets.  It has worked for me a couple of times, and has shown that even though it may have looked great, I actually had a connection between the ribbon and the magnets.  It works on any magnet that's not coated with a non-conductive surface.  Just take one probe and put it on an end of the ribbon mount (in contact with the end you intend to solder to the connection wire) and put the other probe on one magnet, then the other.  In a resistance setting, it should reveal even the slightest connection.  The resistance will be very high, so if your meter does not auto-select for resistance, I'd set it to high setting.
 
8)  All the other materials were just junk and pieces I found that would work for mounting the base and for the casing.  You should also keep in mind that the whole mic will need to be shielded really well.  I made the casing excessively large to let me get my hand inside of it and apply shielding.  Also, it is wide enough for the transformer, and plenty wide enough to accomodate any future preamps, circuits, etc.
 
9)  I assembled everything, wired up the element (being mindful to twist the leads to reject as much Electro-magnetic interference), wired everything into the transformer, and...bingo.  Ribbon microphone.

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Yet another Bad photo
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Sorry it's not more clear

The heart and soul.  The ribbon element, magnets, and base.  This is actually the second prototype.  I may put some pictures up of the first one, but it is ugly.  Raunchy, really raunchy. 
All of this was made from scratch (except for the magnets).  I had to, because I couldn't find anything that would remotely work well and perform like I wanted it to.

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