QuestionQUESTION: Hi:
I am thinking of a way to directly convert electric energy into sonic energy -- for audio playback. The loudspeaker passes electric current through ionized nitrogen -- in the form of nitride ions.
If my music room had nitride ions [nitrogen ions with 3 extra electrons] in place of nitrogen gas, would it be easier to directly convert electricity into vibrations of air molecules? My guess is yes. Of all the gases on the earth's atmosphere, nitrogen is the most abundant -- 78%. Chances are, my music room currently contains 78% of electrically-neutral nitrogen, with about 21% oxygen, 1% H20 vapor, and traces of CO2 and other gases.
If the room with my audio equipment had 78% nitride gas [instead of nitrogen gas], then it would be significantly easier to make those nitride molecules vibrates analogously to an AC electric current passing through the air containing those nitride ions. Right?
Nitride ions are negative so they will try to move away from the electrons. As they attempt, they [I think] will vibrate similarly to the way the electron current oscillates.
I chose nitride ions, because nitrogen is the least reactive of all the commons gases in the earth's atmosphere. Oxygen, hydrogen, and others are not so calm in their ionic states. For example, oxygen will convert to ozone when ionized.
Do you think this would work out? Will it efficiently playback the music?
Thanks,
Green
ANSWER: I have no idea. I would be interested to hear the result of your experiment.
In earlier days there were a number of high voltage devices that drove ionizers of one kind or another. They made really good tweeters - high frequency response but their polar patterns were crazy due to the configuration of the ionizing compartment that restricted the air pressure gradient patterns. Also, safety and repeatability in the lab made them unwieldy. But, these I am speaking of were not using nitrogen, just ionized air and high voltage streams that were modulated by the audio signal.
I would judge that you will have difficulty reproducing audio frequencies in the bass register - say below a few hundred Hz.
You might want to correspond with MIT Media lab where a good scholar is working on some similar technology. Actually, he has graduated and now running a company here:
http://www.holosonics.com/PR_TR100.html
and he might be a resource person in this area.
Also, Dr. Bill Gardner, graduate of MIT Media lab is much involved with loudspeaker development tools. He can be reached at:
http://www.wavearts.com/
You can find other experts in this field with some googling around. Keep me informed.
Cleggsan
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QUESTION: Thanks for your reply. Unfortunately for me, I don't have the devices to conduct my experiment, but I will try to contact those at MIT and Wavearts.
I have posted a similar question in the rec.audio.tech usenet newsgroup. One of the responses I got was that nitride is toxic it oxidizes and converts to nitric acid which breaks down tissues in the lungs.
So, in the meantime I have another question.
Since my recent questions regarding methods [e.g. electric arc speakers, plamsa speakers and ionophones as well as the nitride technique previously discussed] of directly converting electricity to sound have not been efficient methods, my next question is:
What is the most efficient way to directly convert electricity to sound?
Thanks,
Green
ANSWER: Efficiency of conversion has much to do with the acoustics of the space where the conversion takes place.
As you can guess, because such a great percentage of all loudspeakers and sounders are based on the magnet/moving diaphragm technology, it is thought by most experts to be at least the most practical if not the most efficient.
Amplifier technology for driving low impedance voice coils is very cost effective and manufacturing of diaphragms and magnetic forms is very cheap, relatively.
It turns out that as the frequency changes the acoustics requirements become very different. Low frequencies require large amounts of air movement because the air is very soft at low frequencies.... hence large radiating surfaces and long movements of the diaphragm are necessary. At high frequencies the air becomes very brittle and the acoustic wave propagates more like a flashlight beam.
So, for accurate or high fidelity reproduction of music, for example, accuracy of the reproduction becomes more important than efficiency.
A very efficient transducer is the piezo effect which requires a high voltage drive to cause physical bending of the material - with very little current. But the piezo speakers are not practical for the full range of sound; they do not displace enough air for low frequency reproduction.
You might want to study the Olsen book on loudspeakers or any of the many others that deal with loudspeaker physics and inventions.
The Harry Olsen book is near the bottom of this site:
http://www.raymondaudio.nl/books.html
Also, see my other comments to another correspondent at:
http://en.allexperts.com/q/Audio-Systems-835/Brand-loudspeaker-1.htm
Nice to hear back from you.
Cleggsan
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QUESTION: Okay. Let's say I'm looking for an electrostatic loudspeaker that has the highest treble response and can handle the loudest sounds [without clipping] of its kind. I am not really a fan of bass. I like treble and would like the loudspeaker to be able to withstands extreme loudness without clipping. It should also be handle to best handle already-clipped waveforms without suffering any damage.
Is there anything close to what I am looking for that I can find in an audio store?
AnswerProfessional people deal with this all day. Rock concerts and big public spaces use drivers that can handle hundreds and thousands of watts. But, there are many; horn/driver combinations, piezo horns, electrostatic speakers of many kinds, ribbon tweeters and so on.
You have got to narrow it down to an SPL level, size of audience, power input level, etc. before I can be very specific.
C
