Indirect method of sound creation

jzagaja · 19th November 2008, 06:08 PM

Old technology in a new form:

http://www.atcsd.com/site/content/view/34/47/

Its response measured. The only one source is here at diyaudio ;-)

scott wurcer · 19th November 2008, 06:19 PM

The LRAD is more fun, it puts all of its Watts in the audible range

kelticwizard · 4th December 2008, 04:27 PM

The chart has the following axis:

Quote:

FR Magnitude dB re 20µPa/V

I am familiar with 1watt / 1 Meter term

I am familiar with 2.83V / 1 Meter term, (not the same as above if impedance is not 8 ohms)

Not familiar with this term.

What is the norm for this measurement? Should the ideal line be flat, or is it some kind of power measurement where the ideal line should be sloping down?

jzagaja · 4th December 2008, 04:45 PM

Wikipedia: The decibel (dB) is a logarithmic unit of measurement that expresses the magnitude of a physical quantity, it is a dimensionless unit. 20uPa/V is 0dBspl - threshold of hearing.

This measurement is uncalibrated - unknown efficiency. Don't know what can be expected from heterodyne transducer - maybe typical bandpass. Some DSP is probably incorporated.

Cheers,

kelticwizard · 4th December 2008, 06:27 PM

Jzagaja:

Thank you. By DSP do you mean equalization? Because if the plot is not equalized, it would seem that not that much equalization is necessary up to 10kHz-it really "rolls off the table" after that. But that should be more than adequate for PA work.

I also gather that the "column" they talk about is horizontal rather than vertical. Sort of a sound laser from source to point.

I wonder if they have directionality charts which show how quickly the SPL goes down once you leave the area of maximum SPL.

jzagaja · 4th December 2008, 06:47 PM

I had only 5 minutes and laptop. Now don't have any chance of putting hands on them. Directivity is really extreme - forget about horns. Here you hear almost nothing outside the beam.

19th November 2008, 06:19 PM	#2
scott wurcer diyAudio Member Join Date: Jan 2004 Location: cambridge ma	The LRAD is more fun, it puts all of its Watts in the audible range __________________ Clay is embedded in our subconscious. It has been there for at least 50,000 years.

4th December 2008, 06:27 PM	#5
kelticwizard diyAudio Member Join Date: Sep 2001 Location: Connecticut, The Nutmeg State	Jzagaja: Thank you. By DSP do you mean equalization? Because if the plot is not equalized, it would seem that not that much equalization is necessary up to 10kHz-it really "rolls off the table" after that. But that should be more than adequate for PA work. I also gather that the "column" they talk about is horizontal rather than vertical. Sort of a sound laser from source to point. I wonder if they have directionality charts which show how quickly the SPL goes down once you leave the area of maximum SPL. __________________ "A friend will help you move. A really good friend will help you move a body." -Anonymous

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4th December 2008, 04:45 PM	#4
jzagaja diyAudio Member Join Date: Jun 2004 Location: Szczecin	Wikipedia: The decibel (dB) is a logarithmic unit of measurement that expresses the magnitude of a physical quantity, it is a dimensionless unit. 20uPa/V is 0dBspl - threshold of hearing. This measurement is uncalibrated - unknown efficiency. Don't know what can be expected from heterodyne transducer - maybe typical bandpass. Some DSP is probably incorporated. Cheers,

4th December 2008, 06:47 PM	#6
jzagaja diyAudio Member Join Date: Jun 2004 Location: Szczecin	I had only 5 minutes and laptop. Now don't have any chance of putting hands on them. Directivity is really extreme - forget about horns. Here you hear almost nothing outside the beam.