EM Coil Sounds and Concepts

In this video I give some examples and details about EM coils (aka EMF coils, aka pick-up coils - these can be found online for under $10). It's a specific type of field recording that can be useful and fun for finding some different/personal sounds for your ambient mix or sample library. I talk some about signal level safety and also a little bit about theory. I give a bunch of hands-on examples of various setups and sound sources. Not trying for much in the way of music in this video, but the last shot includes an underlayer of a little chiptune loop that I made in the Pulp mini-DAW. If you like chiptunes you might want to check out Pulp. It's a web-based development tool for the Playdate handheld console (see link below). It's free to use (with an account that saves your work) and you can skip over all the graphics parts and go straight to the audio tool. I just recorded the loop straight into OBS Studio.

Thanks for watching!

TIMELINE

00:00 STARTER
stuff in my kitchen

00:45 INTRO
a discussion of essential concepts (and safety)

05:18 COIL SETUP BASICS
i show various methods for getting the sounds, also an example.

17:41 A LITTLE THEORY
very little. it's easy to sort of think that a lower derivative is all you need to get sound. BUT, that's thinking of it as a localized thing. Say a cubic curve for the field that gives a signal here like a parabola. A parabolic 'bump' would indeed make a sound, but the discontinuity is required (a bump on a flat line). So, higher order functions, zero-crossings, etc. seems you could certainly make audio with basic functions... but it's just easier to think in terms of a fourier transform: waves, noise, complexity - these are all things within our everyday EM environment that can yield interesting sounds.

23:35 SOME EXAMPLES
not the best. i'm confident that you can find better examples! the magnetic sand timer was a challenge to do on camera (again, careful working with subtle signals - because a cable crackle can be unexpected). i think it does make a sort of weird / alien noise. will investigate and post on IG at some point. then, the solar powered rotation stage. i had been listening to it in sunlight. it was LOW, but actually hearable. for this shot it was down with the elephants or such, maybe 10 Hz? i sped it up 4x to hear. caveat: i did speed changes throughout this video, but the only synced shot is at the end (see below). i am a big LittleBits fan, and this sort of coil tech is a great add-on. for example, instead of getting another Speaker Bit to have another oscillator output in parallel - i can run the oscillator into a motor Bit and use the coil to get the sound (probably with significant distortion).

32:41 OUTRO

34:16 ENDER
well, i did the recording into the tape at full speed, but there is an art to having the half-speed performance come out well-adjusted and full. this sort of 'sound sampling' setup really benefits from having another layer of sound. i decided to use an unrelated loop from the Pulp mini-daw (see above for more details). the video here is at half-speed (done in editing on PC), but the audio is at 'half-speed' from a Lanier dictaphone of unknown age (which is awesome, btw) just by changing the tape speed setting, and then the sound was routed through the Korg NTS-1 for reverb (and a bit of delay) and into a (digital) field recorder. the two VERY different half-speed sources seem to start to spread a little by the end of the shot, but i still feel like it turned out okay!

LINKS
https://play.date/dev/