As I was driving to my daughter's rehearsal this afternoon, I thought
about Bart's videos (and all the other musical TCs).. and realized that we
should think about what kind of instrument a TC is, and my best guess is
that it's sort of like an organ that can play only one note at a time.
There's not much in the way of dynamics. You have to have enough "bang"
to get a breakout, and the sound from a small spark is not a lot different
from a big spark. So it's like a pipe organ in that way. You get big
changes in volumes by adding ranks of pipes.
Can it do polyphony.. I think so, in a limited way. You're basically
generating a pulse stream. And I could logically "OR" two pulse streams,
one at "C" and one at "E" for instance, and I should hear two notes. Easy
to test with some .wav files
How many octaves range does it have.. you can go pretty low, but the
loudness will drop off. The bang size is roughly constant, so the
acoustic power as the rep-rate goes down goes down with frequency, and
Weber-Fechner law means that lower frequencies "sound" less loud for the
same power. What's the top frequency, maybe a couple octaves above middle
C?
Can we make a TC put out a sound that's different than the sort of buzz we
normally get. Perhaps, if you send closely spaced double pulses? What
does something that is, say, bang, 1 ms, bang, 9 ms, bang, 1ms, bang,...
sound like.. Yes, about 100Hz, but there'll be some interesting harmonic
structure that would sound different. Then there's all the old techniques
from early synthesizers: Two pulse trains at the same frequency, one with
a bit of FM on it (a sort of vibrato/tremolo effect)
But here's the intriguing thing.. I've always wanted to build a setup with
multiple TCs that can do real polyphony. Originally, I had ideas of
multiple rotary spark gaps a'la a Hammond organ and tone wheels (someone
actually did this at the turn of the 20th century, I have found).
And, because I'm a spark gap kind of guy, I started building a multiple
triggered gap.
but these days, the DRSSTC is SO much more controllable.
If you could control the RF phase (which I would imagine you could, with
clever timing), you could phase multiple coils so that sparks would
preferentially strike between toploads.
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