Thanks! Obtaining the T/S parameters is what I'm working on. I have a 'woofer tester' that does a good job (agrees with the classic 1K Ohm method) BUT For some reason it goes bonkers on certain drivers (Fs 4Hz AND -Qts!) So I'm trying to streamline my manual method. I'd like to use the Fl & Fh = -0.707 Zmax method for Qts (since my scope has a specific graticule for this purpose) and absolute values are not needed (Zmax is set @ full scale): Qts=((Fs/(Fh-Fl))*(Re/Zmax)...........Actually 'Qo' ???? Anyways then comes Vas (using added mass). But if it could be calculated at this point it would be slick. So Rou=1-(((Zmax/Zmin)-50)/10) doesn't work anymore ? Technology Marches On ! ................. mike