There are lots of different types of microphone, with the ribbon microphone being one of the rarer ones. Commercial versions are often prized for their tone and frequency response. You can make your own too, as [Something Physical] demonstrates using a packet of chewing gum.
Yes, the ribbon in this microphone was literally gained from Airwaves Extreme gum. It’s got nothing to do with freshness or the special mintiness quotient of the material, though; just that it’s a conductive foil and it makes the YouTube video more interesting to watch.
The gum wrapper is first soaked in hot water and then acetone, such that the paper backing can be removed. The foil is then corrugated with a tube press with some baking paper used for protection during this delicate process. The “motor” of the ribbon microphone is then produced out of plexiglass, copper tape, and a pair of powerful magnets. The ribbon is then stretched between the magnets and clamped in place, acting as the part of the microphone that will actually vibrate in response to sound. As it vibrates in the magnetic field, a current is generated in response to the sound. From there, it’s just a matter of hooking up a custom-wound transformer to the wires leading to the “motor” and it’s ready to test. It works off the bat, but there is some noise. Adding shielding over the transformer and a proper enclosure helps to make the microphone more fit for purpose.
If you’ve ever wanted to experiment with microphone construction, it’s hard to go past the joy of building a simple ribbon mic. You can experiment at will with different sizes and materials, too; you needn’t just limit yourself to different brands of gum!
We’ve featured some other great mic builds over the years, too. Video after the break.
Great project ;)
I just have one question , why not just use normal aluminum foil in place of the gum one ?
If it’s the same it will be easier :)
It’s substantially thicker in most cases.
Ha ! ok ;)
Thank you.
I remember seeing an “how it’s made” episode about gold foil. Gold is very ductile and can be thinned to something just a few molecules wide, can be hannered so thin it’s transparent. and that’s actually how they did it, they layered several sheets together between paper sheets and hammered the lot thinner. I think the same could be done with aluminium foil and baking paper?
It’s been a shockingly long time since I last did this, but… iirc you can flatten a gum wrapper, hold it horizontally with the paper side down and run a lighter flame along the paper, causing the Al foil to come off right away.
Yes! A bit of heat… much more elegant solution to the “paper backing problem” (as I recall).
I did not expect the sound to be this good. The foil tension doesn’t seem to be too critical ?
The separation of the foil is super fetishistic. Your parents won’t find out, guys!
Fantastic video and that banjo sounded so good!
In the Land of Ago, with care the foil could simply be peeled away from the paper. I used to do this as a kid to make electrical ‘fuses’. A narrow strip left by cutting indentations in the foil would melt through when a short circuit from a couple of batteries was applied.
That’s a “prison lighter”.
A very cool project, well-executed on a limited budget.
If I was doing it I’d try to find a better way of connecting to the ribbon – that pressure-only junction between aluminum and copper may not hold up very well in the long term. I think I’d also want a better-damped enclosure – either the same box lined with some kind of damping material, or a plastic box lined with copper foil and damping material.
That said, it sounded really good. I’d be interested to hear how it sounds with something sound-absorbent on the back side to reduce the amount of reflected sound hitting the ribbon.
It seems that I was wrong in being concerned about the contact reliability. The pros do it pretty much the same way:
https://www.youtube.com/watch?v=QG_fba2km00
The video above shows microphones from Royer Labs being assembled, adjusted, and tested. Very interesting stuff.