Speaker testing without anechoic chamber

[KSTR]

Lay the test source on it's back in the middle of the football pitch.
Mount the microphone of a mast and hang it about 10' above the upward facing source.

Doesn't work unless you dig a pit as well, the baffle must be flush with the earth surface, otherwise you will see a pretty perfect comb filter pattern, depending of the depth of the box.

 

[CharlieLaub]

I strongly suggest that you get a copy of a real measurement software, like ARTA. It's free as a demo version (but full featured). Then read the following tech note about measurements:
http://www.artalabs.hr/AppNotes/AP4_FreeField-Rev03eng.pdf

This goes in to more details about the science behind these measurements:
http://www.xlrtechs.com/dbkeele.com/PDF/Keele (1974-04 AES Published) - Nearfield Paper.pdf

This is how to do it!

-Charlie

 

[shkumar4963]

Deleted

 

[ampetrosillo]

I'll revive this thread to ask what kind of measurements is this guy doing.

Starting from around the 14' mark. Basically he is suspending the microphone from a plastic tube, which is attached quite a distance away from the microphone to a stand, and he's measuring the speaker response of woofer and tweeter in a coaxial outdoors, with the speaker mounted on a stand. He claims that this is comparable to an anechoic chamber.

 

[aslepekis]

I'm hamstrung by only speaking English, but I'd guess it's a gated impulse response. He has the microphone on the end of a long tube to avoid the very early reflections that would a present with a "traditional" mic stand/holder. Above around 1kHz or 2 kHz, it won't be any different to an anechoic chamber. Below that frequency range the results will become of progressively lower resolution to the point they're of no value.