TI-Calc speaker building


2001-07-30 1:35 am
I just wanted to bounce some ideas off of the forum here. I, like many students, have a TI (-83) graphing calculator. I have found the CBL (calculator based laboratory, a device which facilitates I/O with different probes) online for $50, and the corresponding measurement mic for $35 (or one could build their own, as detailed at www.speakerbuilder.net). I am currently writing a TI calc program that does all the standard crossover and box calculations, but was thinking about adding frequency reponse and impedence measurement to it ( impedence would be measured through a voltage probe in and freq. counter in a voltage divider). This would create a very mobile, easy tool with which the amateur could probably get some decent results, assuming the mic is decent enough (maybe it could be calibrated).
I want to be able to combine the frequency response of the calulated filter with the measured driver response to get an estimated "real" freq response, much like the high-priced computer based systems do.
My question is this, how do i calulate filter frequency responses? I want to find the attenuation at a certain freq. for a given filter at a given freq. Are there standard formulas or is it some voodo that only the high-priced systems can do? I think it has to do with the Q, but I can not find any formulas. Thank you for reading all of this and thank you in advance for any help!