New type of mid air laser show

[Xytrell]

So what would it sound like if you started at 10hz and slowly ramped up to 1000hz? Would it spontaneously create resonances at random intervals? - a bit like a three-year-old playing the piano? Or is this a rare occurrence?

[mixedgas]

So what would it sound like if you started at 10hz and slowly ramped up to 1000hz? Would it spontaneously create resonances at random intervals? - a bit like a three-year-old playing the piano? Or is this a rare occurrence?

YES, RANDOM MIXES AT RANDOM TIMES.

Google White Noise and Pink Noise and Grey Noise.

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

Yes, you'd get the whole interharmonic distortion table. Borrowing one from the RF world, audio is similar but much more complex. OK, you have a 640 hz rep right now, so

You'd get things like
N + N/2
N-N/2
2N + 1/2N
2N-1/2 N
2N+ 3/2N
2N +3N
5N-3N
Then N+N/3 and the series repeats.....

And so forth. And thats just from the leading edge of the plasma popping. The noise from the total plasma heating of the air would be much longer and take a long time to decay, and be purely white.


So just from the 640 hz, you'd get 240, 480, 960, 1,440 , 3200, ad infinitium... And thats just a even series... Not a ODD. ODDS are far worse to calculate... And then at high powers, such as in the nonlinear laser pop, those chains would mix again. so now you have 240x1,4440 etc.

Here's a table for RF. RF works with whole integers, so its easier Sound works with whole integers and odd fractions as well. RF is easier because its predictable. Sound is chaotic and white means it contains ALL frequencies, so each of those mixes again in a infinate series in the plasma, and then in your ear. Oh, and to louse it up even more, some of the tones DONT exist until they hit the ear or the microphone which is where they actually undergo nonlinear mixing.

http://michaelgellis.tripod.com/mixersin/table1.gif

The signal strength numbers in that table are log10 P1/P2 where P2 is the reference number.

[f.sub.OUT] = \[Mf.sub.LO] [+ or -] [Nf.sub.RF]\ (1)

where

[f.sub.OUT] = output signal for the mixer

[f.sub.RF] = input signal for the mixer

[f.sub.LO] = LO frequencies for the mixer

M,N = integers (0,1,2,...)


Steve

[dar303]

A cool thread just turned very interesting! There is a lot of knowledge hear and with the links you guys publish and wiki/google it sends you out on all sorts of interesting tangents!

[Pangolin]

FYI: They are a Pangolin client. They use our LD2000 SDK and QM2000 to control this. In fact, they use LD2000 to create the shapes and Showtime to animate them too...

Bill

[CDBEAM]

Although I am always amazed at the level of technical knowledge( Audio in this case) many of you have...the bottom line is if this thing makes all that " snap, crackle and pop " noise....it will NOT deliver a viable presentation format....after a few seconds of that blasting your ears.....I...for one would be outta there !!!...but....I am NOT surprised that the " brain " for the beamswinging is Pangolin.....OK Bill.....now can the thing run silent ???

[Pianoman]

I have a question. Since the audible frequency is determined by the pulse rate of the laser, could the pulse rate be varied to create a series of desired pre-planned frequencies to create music (although the music would sound as though it was being played on an old square wave synthesizer)? Or would this make it impossible to break down the plasma in the correct intervals to create the desired graphic? I'm sorry, I didn't completely understand the pdf. but I tried to wrap my head around it, hope this question makes sense. Basically I'm wondering if the laser could create the same audio effect heard in this video:
http://www.youtube.com/watch?v=qQ_1jtpAK5w

while still maintaining the desired visual effect?

The basic concept seems to be the same (at least in my mind, correct me if i'm wrong). The pitch of the tesla coil in the video is controlled by how many times it is turned on and off per second, as explained in this video (explanation at 6:50):
http://www.youtube.com/watch?v=cOkTrqTd0hw

Thus the pitch is a result of how frequently the plasma is forming. The rate at which it forms changes the frequency at which the air waves vibrate. Right?

[buffo]

Johnathan;

You just finished reading several posts explaining how the beat frequency is in fact *not* the major component of the sound you hear and that the "pitch" of the sound is dependent on highly unpredictable, chaotic interferences, and your first question is "how can this be used to create music?"

Seriously?

Adam

[Xytrell]

While we're on the topic, how are tesla coils modulated to make music?

[buffo]

They modulate a single source of sound (the arc from the coil) and rely on the ability to turn it on and off rapidly to get tone. Nevertheless, it's complicated, and the tuning is not easy. If you're genuinely interested, here's a link to a primer.

How is this different than the plasma display, you ask? Because unlike the arc of a tesla coil (which can be extinguished nearly immediately with great precision), the plasma hangs around for around a fifth of a second, and the decay time is random and non-linear . Thus the sound timing is also random. Also, you have between 128 and 200 of these little sound sources all interfering with each other, which is not the case with the tesla coil. So getting a "pitch" from the tesla coil is relatively easy (and predictable), but not so for the 3D display.

Also, if you're thinking about building a singing tesla coil, know that there are other ways to create music even with a continuous electrical discharge. But both of these examples are different from the 3D plasma display, for the same reasons listed above.

Adam

[daction]

i have just seen this and will begin reading it all . this really is the shit we are talking about nice one boys.