The SW tools provided on this page are free and offered on an as-is basis. However, if you feel these small programs are useful and want to give something back, then please consider donating. There's a Donate button at the bottom of the page. The money will help support my horn loudspeaker research project, which has very little funding from the university.
This spreadsheet calculates the required resistor values for an L-pad based relay attenuator, and allows you to see the effect of substituting real resistor values.
This is a program I wrote many years ago. It can calculate attenuators, L-pads for loudspeakers, heatsink thermal capacity, passive and active RIAA network values, parallel and series notches for loudspeaker crossovers, first order series crossovers, and air core inductors.