My plasma speaker

I've been recently making some sort of experiments with high voltage (3kV to 70kV). I have two interesting conclusions:

1. High tension transformers have a narrow frequency response. That means that you have to know their frequency of operation to make them work properly. That also makes them suitable to use as FM decoders.

2. Once an arc is produced, the current used to make the system work is not necessarily very high (I used 15V 1.2A, or about just 18Watts).

To put this facts to work, and for the fun of making it, I built a plasma speaker:



Not quite efficient but WTH!