ACTIVE FILTER CALCULATORS
http://changpuak.ch/electronics/calc_08.html
http://www.vwlowen.co.uk/java/audio.htm

AGC amplifier
http://electronicdesign.com/Articles/Index.cfm?AD=1&ArticleID=6272



ACOUSTIC RESONANCE

Great site with lots of pages on resonance, calculators, etc
http://hyperphysics.phy-astr.gsu.edu/Hbase/sound/rescon.html

http://hyperphysics.phy-astr.gsu.edu/Hbase/hph.html


Calculate wavelength of sound
calculator and equations etc at
http://www.sengpielaudio.com/calculator-wavelength.htm


resonant frequency of closed-end tube

	L + 0.4d = n (wl / 4)


300Hz= 1.14 m
600Hz= .57 m
900Hz= .38 m
1200Hz= .28m


See images of harmonic locations in closed tube for mic placement

http://media.paisley.ac.uk/~davison/labpage/tube/tube.html


MUSICAL NOTES AND SCALES
has tables and sound generator
http://ptolemy.eecs.berkeley.edu/eecs20/week8/scale.html