wtf is free_keithley?

free_keithley is a free tool that connects to a Keithley 2015 THD multimeter and visualizes audio measurements on your computer. The Keithley 2015 is a specialized piece of lab equipment often used to analyze audio signals, and this software gives you a graphical interface to run tests and generate plots without relying on expensive proprietary software. The software provides several testing modes. You can measure total harmonic distortion (THD and THDN) and see the distortion level of individual harmonics. Other modes let you plot how distortion changes as you vary the power or frequency of a signal, log DC voltage over time, measure frequency response, and view FFT (fast Fourier transform) spectra. Each mode is a separate Python script, so you run the specific test you need by launching the corresponding file. This tool is aimed at audio engineers, electronics hobbyists, and audiophile equipment reviewers who already own or have access to a Keithley 2015 multimeter. For example, someone testing an audio amplifier might use it to check how cleanly the amp reproduces signals across different volume levels, or a person evaluating a piece of audio gear could chart its frequency response to see how flat its output is across the audible spectrum. It essentially turns a capable bench multimeter into a more practical audio analysis workstation. To use it, you need a computer running Python 3.10 or later. The multimeter communicates with your computer over a serial connection, so the software bridges that hardware link and displays the results using standard plotting libraries. The project is built as a collection of individual scripts rather than a single unified application, which keeps things simple and modular but means there is no all-in-one interface, you launch each measurement type on its own.