Newbie Question- How to generate infrasonic tones

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whyuncertainty
whyuncertainty's picture
Joined: December 1, 2011

Hi. I'm deciding whether i should buy and learn audiomulch, but i want to be sure its capable of what i'm looking to use it for first. can anyone tell me if its possible to make a simple sine wave synth that generates frequencies between 5 and 20hz triggered by a standard midi controller? thanks so much!

Winslow17
Winslow17's picture
Joined: December 29, 2010

I don't believe so, unless you have a plug-in (VST or AU) that contains a sine wave generator, or oscillator, capable of working at such frequencies. AM's own 10Harmonics contraption bottoms out at 20Hz. There are some LFOs in AM that work at very low frequencies, but they are not generating sound, only modulating other parameters.

Perhaps you could create a sine wave at a higher frequency, record it, and play it back at half-speed, or whatever, to get the effect you want. AM certainly would enable that. With ingenuity, many things are possible in this program.

Ross, the program's developer, probably has a better idea, or two.

I'd be curious to know what you plan to do with such sine waves. Demolish buildings? Trigger earthquakes? Can anyone hear such waves? What speakers and amp would you use? Can any computer's sound circuitry handle such low frequencies? Somehow, I doubt it.

Me, I recommend you just download the program as a demo and try it out. You'll have lots of fun, and you'll find out what you can and cannot do with it. Cost: zero. Time allowed: 2 months. Potential: unlimited. (No, I don't work for the company.)

whyuncertainty
whyuncertainty's picture
Joined: December 1, 2011

Hey Winslow. Thanks for the response. Yeah, i know it sounds strange... i'm working on an experiment with a buddy... there are some sound cards/interfaces and amplifiers that will hit 5hz and a custom speaker system works it out... nothing at huge volumes... i guess most of the equipment is meant for film. anyway is there anything you could recommend that would work? i don't want to be stuck with these old 70's style speaker testing oscillators... thanks!

Winslow17
Winslow17's picture
Joined: December 29, 2010

Seems to me a sine wave is a sine wave, no matter what the source or the frequency. An audio test oscillator might be just the thing, though I don't know if those devices typically operate at 20Hz and below. You could probably rent one somewhere, or buy one on eBay. (In the old days, you'd have been able to build your own from Heathkit. My father built an audio oscillator from vacuum tubes in the early 1950s; it was in a wooden box he built, and inside was a small light bulb, as used in a fridge, there to stabilize the temperature and frequency!)

As you will see, AM can stretch audio loops (using the Loop Player contraption), and you might use that to drop the frequency of a 40Hz tone to 20 and below. Just do the math. The Arpeggiator contraption generates sine waves, but only on a tempered scale, so you may not get the fundamental you want; it has a Detune knob, though, and that might help. The 10Harmonics contraption generates sine waves, too, at any chosen frequency down to 20Hz.

I am not sure how you'd go about triggering such a loop with MIDI; perhaps others here have ideas.

Like I said before, get the program and start fiddling. You'll have a blast, no matter what. And nothing to lose.

Good luck. Let us know what happens.

Ross B.
Ross B.'s picture
Joined: April 11, 2009

TestGen contraption generates tones down to 10Hz. If you need 5Hz I can tweak the lower range for you.

Can you explain why you need the MIDI triggering and how you expect that to work? You can control most parameters in AudioMulch from MIDI but the TestGen doesn't play "notes," it just oscillates, so it doesn't support playing notes from a MIDI keyboard (you could set up a gate/mute that's opened /closed via a midi note though.

Ross.