Putting it together
If you have a bandsaw, obviously, use it with a metal blade, proper speed setting - and enjoy.
If you only have hand tools, like myself - cut the tubing to size with a pipe cutter. A hacksaw will
just make an uneven cut that you will curse. Use the hacksaw for cutting the
vents. If you have a dremel tool, you could do some really nice vents with that
instead. With a metal file, file the inside of the tubes, because the pipe cutter will compress them slightly.
If you want the same satin look as my microphones, start with a 60 grit sand paper. Grab the pipe with the paper and rotate it in your hand. Sand only in this direction. Move to smoother paper, repeat. Finish with some fine steel wool. How much or little you want to do here is up to you.
Since the B3M XLR connector is smaller than the body, something has to be
used to act as a gasket. I found that a plastic hose adapter tube thing at Home
Depot worked perfectly.
Cut a narrow piece (one .49 cent tube is enough for plenty of mics), and slip it over the XLR connector's screw threads. Take a bare piece of wire, and connect it from the ground pin and lay it over the plastic tubing/gasket. This way, it will make a connection with the body of the microphone.
Gently slide the circuit into the microphone body so that the XLR plug butts against the body. It won't go in all the way because of the plastic pipe/gasket. However, get that bare wire to connect to the body of the mic. Watch out for those .47uf film capacitors rubbing against edges. Test the microphone by gently plugging it in. At this point, it won't sound too good (You will hear a 'flangy' tube'y sound to say the least), but it should work. There should NOT be buzzing, hissing, static, AM radio stations, or weak output. If it exhibits any of the problems, check everything again closely. Look for a wrong connection, a solder joint that isn't good, a wire that may have been missed, improper grounding, crossed wires, etc.
If you plug the microphone circuit in when it is not in the body, you'll be amazed by the amount of buzzing and humming. The metal body is an important shield.
If all is well, shut everything off, and pull the mic circuit out of the body a little. Carefully stuff the inside of the microphone XLR side first, with insulation.
Fiberglass
Sound Absorbing Sheet 1" Thick X 36" Lg X 36" Wide,
Yellow Sheet
|
$3.26
|
|
This can also be
purchased at Mcmaster.com
Once again, the minimum is enough to do many, many microphones.
You want to fill the body up as much as possible. It provides two purposes. It will hold everything in place, and, extremely important - deaden the body sonically. Once the back end is filled with the fiberglass, it's time to press the XLR connector into the body. This is best done with a clamp. A large C clamp will do nicely. Put something protective (a flat piece of wood or metal on either end of the tube - you don't want to dent or collapse anything now. Then, press the XLR into the body. Make sure that bare wire is firmly pressed against the tube.
Next, fill the body with insulation from the capsule side. Carefully! This will again hold everything in place, including the capsule. Don't fill to the top, but only to your bottom vent. You need sound to get in there through the side vents.
At this point, plug the mic into your system again. It should now sound GREAT. If you hear the body imparting any characteristics, see if you can put more insulation in.
The last thing to do is cut a small piece of Brass mesh and
shape it into the top grille. I used the handle of a screw driver to shape the
mesh. A little practice will quickly reveal the best way for you. With the
amount of mesh the minimum order is, you'll have no shortage with which to
practice.
Hint: cut a circle of mesh that has a slightly larger radius than the tube.
Once you have the shape, cut a little piece of foam to help with wind noise.
This can be purchased from http://www.Markertek.com Part # mf-w
Or - you can buy open cell foam in the form of a wet/dry vac reusable foam
filter at your local hardware super store. It works just as well.
Carefully fit the grille into the front of your microphone and then.
Enjoy your
microphones!
If you build your own based on these pages, please let me know.
The
total cost for a pair of microphones should be under $100.00.
Sonically, they will match very well against microphones costing twice or more
than that per microphone!
Obviously, the
microphones are the first step in the recording chain. Preamps and the recording
device are just as important. I recently took these microphones to a studio and
was amazed by how good they were. I had no idea!
At home though, I am using my laptop and a USB interface. Currently I'm using the Aleisis IO|2. It does the job, but with the $149.95 price tag will of course have limitations. Your sonic mileage will vary based on what you plug the microphones into.
I recently built a two channel Microphone Amplifier called the "Green Pre". It is a professional level Preamp with very clean sound and incredible gain. I'll detail that in the near future.
Continue to my OMNI microphones
http://scotthelmke.com/microphones.html
The man!
The Legend!
http://www.freeforum101.com/forum/micdiyer.html
http://www.epanorama.net/circuits/microphone_powering.html
And join
http://groups.yahoo.com/group/micbuilders/
http://www.prodigy-pro.com/forum
Email me if you like