Re: [TCML] tcs as musical instruments...

[Michael Twieg <mdt24@xxxxxxxx>]

There's not a huge amount that can be done to change the tone produced by a
DRSSTC.  The peak-to-RMS power ratio they put out is very high, giving a
sound that has many strong harmonics.  This is especially bad at low tones
but not so bad at high tones.  This phenomenon is determined by the physics
of how arcs form and give rise to sound; the breakout of an arc will always
be sudden and powerful, and there's no real way to soften it (I have to
mention that Steve's QRSSTC designs do this somewhat, but so far the QRSSTC
doesn't seem to be suitable to music due to it low rep rate).  Simply put,
highly distorted sound is built into the physics of the DRSSTC.  And while
polyphonics are possible (either using one large coil or several separate
coils), the result will always be underwhelming because the combined output
will be polluted with tons of harmonics.

Amplitude modulated CW coils are capable of generating very low distortion
sound, but they are monstrously inefficient, I kind of wonder if you could
get a decent tradeoff between distortion and efficiency by operating a
amplitude modulating a CW coil like a class B or class C amp.  But I
imagine it would still end up being too efficient for real performances.
And CW coils are generally less impressive visually, compared to high power
DRSSTCs which produce very long arcs which act much more "lively" than the
arcs or plasma "flames" generated by CW coils.

-Mike

On Sat, Mar 31, 2012 at 5:16 AM, Finn Hammer <f-h@xxxx> wrote:

> Jim, all
>
> I almost choked on my porridge this morning as I read this mail of yours,
> and my first thought was: "Where have you been these last 8 years?"
>
> The idea of using a DRSSTC as a musical instrument was originally mine,
> as you ought to know, and I presented it to Steve Conner at breakfast at
> the Derby Teslathon back in 1994. He liked the idea, and modified a
> Roland synth. so that it would act as a combined MIDI interpreter and TC
> controller for all 6 channels.
> http://www.youtube.com/watch?v=L9Jjsv2zr-c [
> http://www.youtube.com/watch?v=L9Jjsv2zr-c]
> I went on to create 6 identical DRSSTC's and the rest is history.
>
> This was a time where both Daniel MCauley and Stephen Ward went public
> with comments like "We don't think there will be any interest in the
> harsh sound from a pulsed TC"
>
> Meanwhile, the Bach video was recorded, with a cheap snapshot digital
> camera, so although the microphones clipped, and the echo in the
> industrial hall was total, the sound was awesome.
> Here you have _real_ 6 note polyphony, 1995 style, never done before or,
> for that matter, by anyone after:
> http://www.youtube.com/watch?v=VOXygoQkXsQ [
> http://www.youtube.com/watch?v=VOXygoQkXsQ]
>
> You brushed up on the lack of volume at low frequencies, here is Thumper
> @68Hz. the key to volume lies in input voltage, a parameter it should not
> be too hard to controll.
> http://www.youtube.com/watch?v=l-FAdM_5E-s [
> http://www.youtube.com/watch?v=l-FAdM_5E-s]
>
> Different voices are easy to produce, just sit down with the synth and
> press the different instruments, some good some awfull, I particularly
> like the stuff from 0:58 to 1:19 and forward
> http://www.youtube.com/watch?v=Vrtu4uolTVc [
> http://www.youtube.com/watch?v=Vrtu4uolTVc]
>
> Simple pulse trains can produce interesting sounds like this V-Twin
> revving up:
> http://www.youtube.com/watch?v=W0scx1WD3sU [
> http://www.youtube.com/watch?v=W0scx1WD3sU]
>
> And the sound of a MIDI saxophone is also interesting:
> http://www.youtube.com/watch?v=ANiKSPtwTVc [
> http://www.youtube.com/watch?v=ANiKSPtwTVc]
>
> So you see, pulse trains, envelope curves controlling the ON-Time and
> input voltage controll for macro volume changes, It's all been done, and
> is just waiting for some young whizzkid to perfect.
>
> Cheers, Finn Hammer still lurkin'
>
>
>
>
> ----- Original meddelelse -----
>
> > Fra: Jim Lux <jimlux@xxxxxxxxxxxxx>
> > Til: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
> > Dato: Lør, 31. mar 2012 03:47
> > Emne: [TCML] tcs as musical instruments...
> >
> >
> > 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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>
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