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jzagaja 19th November 2008 07:08 PM

Indirect method of sound creation
2 Attachment(s)
Old technology in a new form:

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

scott wurcer 19th November 2008 07:19 PM

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

kelticwizard 4th December 2008 05:27 PM

The chart has the following axis:


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 05:45 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.


kelticwizard 4th December 2008 07:27 PM


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 07:47 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.

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