Home Brew Ribbon Mic, Homemade Ribbon Microphone,
Rima Mic - Microphone, Construction, Steve Rima
|My Home Brew
Ribbon Microphone Page
The Rima Mic
Designed and hand crafted by Steve Rima - Copyright 2007 ©
|My original drawing....The magnet slots
were widened to accommodate a larger
0.25" x 0.25" x 2" Neodymium magnet.
Note: I spent almost as much time
sourcing all the parts as I did
fabricating...Thats part of the
Neodymium magnets are very strong.
Don't let their size fool you...They can
injure you very easily if your fingers
get caught between them.
Notice the areas were I
filed down the plastic
to keep the ribbon
from vibrating against
Holes were drilled
for the ribbon
These transformers are specially designed for low impedance ribbon microphones.
Cut a small square into the bottom of the plastic to accommodate the transformer.
Notice that the leads coming from both ends of the ribbon are twisted. This is to
help eliminate external electrical noise which may be picked up by the ribbon.
Here are the finished prototype assemblies.
The Rima Mic2 has a more professional look, and It has basicly the same
ribbon motor design.
Orientation of the magnets is important.
Be sure the magnets N and S poles are facing each other, this will be obvious
because the opposing magnetic poles attract each other...
WARNING ... Insert a wide plastic spacer to fill the whole space between the magnets
before attempting to mount the second magnet. This is to help keep the magnets
apart during mounting and to protect your fingers.
Because of the strength of the Neodymium magnets, it will be impossible to mount the
second magnet without the spacer....Epoxy the magnets in place.
Here are the aluminum mounting plates which hold the ribbon in place.
Keep the plates from touching the magnets...this is because the ribbon element could
be shorted out and your microphone wouldn't work.
|Now to fabricate the housing
I wanted my prototype to have a more finished look, so I
found a perfect candidate for the housing.
*** A standard 3 "D" Cell Maglite ***
You can see that the lead wires from the ribbon are twisted.
I soldered a second red wire to the bottom of the ribbon which I
used to maintain the twist all the way to the top of the ribbon.
The end of the red wire isn't connected to anything. Its purpose
is for shielding only.
Last updated on 5/23/2009
The ribbon is 1.8 micron thick 99% aluminium which breaks
almost by looking at it...a very delicate operation.
For now, I decided to use 1.8 micron material because most of
the higher end mics use the lower mass 1.8 to 2.5 micron
material...the cheaper mics use the heavier 4 - 6 micron ribbon
which is easier to work with.
I used a large medicine bottle cap to create the corrugated ribs
required for tensioning the ribbon.
Gently use your finger to push the foil into the ridges...I'm
currently working on a better way to do this step.
Installing the ribbon is the most tedious and a very steady hand helps.
Position the ribbon between the magnets and loosely install the aluminum mounting plates over the
ribbon...don't tighten yet, or you will destroy the ribbon.
Make sure there is about 2 extra inches of ribbon hanging from the top of the mic.
Center one side of the ribbon, then lightly tighten the center mounting plate..not too tight.
Center the opposite end of the ribbon and gently lay the mounting plate over it.
Gently install the screws, but DO NOT TIGHTEN at this time.
Now for the tensioning trick...
Gently pull the free end of the ribbon until the ribbon isn't sagging, but not so tight that the corrugated
ribs flatten out...If the ribbon flattens out, you have to start all over. Hold steady and lightly tighten the last
of the screws.
This is my completed "Ribbon Motor Assembly".
|Mic Test 2
"Stay" - Instrumental 12 string guitar
By Deborah Page
|Thanks to Paul and Deborah for taking the time to test my microphone ...
You guys are the best !!
Prototype ~ Rima Mic1
Rima Mic2 ( patent pending )