Farfield Calculation Solved (I think) with calculator

[JMB]

Thanks to someone from the PE Board, I was able to solve the problem. Using the What If analysis tool worked for the Farfield Distance Calculator but was a little inaccurate so I was able to set up a profile that brought it to within a very low error range. I think that it is now ready for use and distribution.

Here is a copy of it. I actually did several measurements (10-12 per driver, on 6 drivers and 3 different baffles) and found this to be fairly accurate. Of interest is that the true farfield (where you see a relative sound pressure drop off of a 6.02 dB drop off per doubling of measurement distance) is much more impacted by enclosure dimensions than by the driver dimensions. There is a slight error introduced due to the fact that the drivers are not flat discs but this is not all that large.

As always, I welcome folks to try it out and comment. Enjoy this and I help that you find it useful.

 

[Pano]

I looked at it, but I'm not quite sure what it does or how to use it. I must be thicker than I thought.

 

[Hentai]

Interesting, must be why i like big baffles. Thanks for sharing.

 

[JMB]

Pano, in answer to your question, I think that we often choose to measure our drivers at a distance based upon the lowest frequency we want and set it up with a distance and distance to reflection based upon it. I believe that we often are unaware that we may not really be in the farfield or how much error is introduced because we are not. This little program will tell you how much error is introduced and how far back (driver to mic measurement) you would have to be. Note that the calculation is to the estimated acoustic center of the driver.

Jay