How would you record a tesla coil?

Question

Hello all,

I have an opportunity to record a number of Tesla coils. To put it shortly, would you have any advice as to how to make sure I do not electrocute myself or my equipment? I intend to bring my DR680 recorder, a Rode NTG-3, and perhaps also a NT1a and NT4 (NT4 cause it can handle 143dB SPL). I'll probably throw in the ol' Zoom H2 as well. I was also thinking of maybe buying a cheap dynamic mic like a SM57 or 58 and place that fairly near a tesla coil, using a long cable... As long as I can avoid a spark from the tesla hitting the mic and then having the current travel through the cable and kill my recorder. I can lose a cheap mic but the recorder would be painful.

Another thought is to only run the recorder off batteries, as it may be a bit safer. No plugging into the mains outlets (this is all going to be indoor so that would be theoretically possible).

I've never recorded anything electric / sparking / arcing ... Well apart from a bug zapper after reading that post on Chuck Russom's blog. Clearly there's some risks involved. But I'd like to get as close as possible (or at least get microphones as close as I can) and get hopefully some unique material.

Any tips would be much appreciated!

Regards, Daan

Answer 1

Let us know where to send the flowers and the sympathy cards.... lol, just kidding.

Don't know much about recording instruments but, as a way to protect yourself and your equipment, how about some kind of screen in between the coils and your mike? Battery powered, definitely. The stand for your microphone should be plastic. And the screen could be some kind of plastic mesh of some sort (a door/window screen perhaps?)

Obvious but must be mentioned: you position your equipment THEN give power to the coils while you are quite far from it.

I would think that the induction created by the coils will be quite strong on your mike, are you sure you have to be so close?

Another thing, I would try to make the ambient air as dry as possible (maybe heating the place up a bit with an heater+fan) so to reduce air electrical conductivity.

What voltage potential you think you are generating. Maybe the minimal distance could be calculated.

Good luck. Sal

Answer 2

I've recorded a Tesla coil before...great fun.

The one thing you haven't discussed is where you are recording the coil. I think the room/space acoustics will be a big part of the nature of the sound. They produce a ton of transient, ripping type sounds that will echo quite a bit in a room. The close mic probably won't give you much, and will sound like ripping masking tape (although it's worth a try, especially if you are looking for dry sounds).

I'd take great care in walking around the room to find the best acoustics, and get them to move the coil if possible to a sweet spot in the room.

If you're going for the Ed Wood vibe, I'd record the coil in a really reverberant space.

Have fun and keep yourself grounded.

Answer 3

How big is this thing (current, voltage, etc.)? I'd suggest setting up a grounded Faraday cage/mesh to protect your equipment. That way any stray arcs will head toward the cage and not your mic. What I'm not sure about is if a powered microphone would attract an arc so strongly that the cage won't catch it. If that's the case, a dynamic would certainly be a safer bet. I'll run the powered vs unpowered question by an EE friend and give you an update.

http://en.wikipedia.org/wiki/Faraday_cage

~Cheers

Answer 4

First off, I'd suggest spending some time observing how the machine(s) behaves, and don't be afraid to spend some time asking questions of that nature with whoever will be operating the units. Their experiences could give you some valuable insights to help protect your gear and get the sounds your looking for. The people who work with those things are going to be your greatest asset going into this (they may even be able to tell you what exactly could happen to your equipment chain should a mic get zapped).

Also, keep in mind that it doesn't matter how long the cable is. If a mic gets shocked and it travels along the cable, the intensity of the current won't diminish any appreciable amount over that distance. Maybe the groundings will save the gear, but I'm not an expert in that area.

If you can't get any information beforehand, I'd suggest using some "cheap/disposable" mics feeding a similarly priced recorder for closer perspectives, and using some decent shotguns with your recorder of choice from a little further away. Better safe than sorry.

Answer 5

Im planning to record some of this stuff on Saturday too, but im expecting the guys who run the equipment to be able to advise on what is safe and not let us get dangerously close.

I guess since it will be indoors recording closer will minimise the room sound so Ill probably use a a shotgun mic. I will also take a PZM & a contact mic just in case there is any opportunity to attach it to something interesting.

Answer 6

Erm, how about using a radio transmitter link instead of cable? I guess by now you have recorded the sound already and I for one would love to know the outcomes and if possible, to hear a sample!