Good tools make life much easier. In addition to the common-place tools like multimeters, oscilloscopes, and power supplies, I use a couple of specialized tools for characterization of my audio circuits. Specifically, the HP 8903A Audio Analyzer and HP 3562A Dynamic Signal Analyzer come in very handy. Both of these instruments may be controlled via the HPIB interface. Many of the name-brand, VISA-compatible HPIB controllers are ridiculously expensive. But, thankfully, there are less expensive alternatives. Personally, I find the GPIB-USB Controller by Prologix to provide incredible bang for the buck.
To get the screen shots of my HP 3562A, I use 7470.exe included in KE5FX’s GPIB Toolkit. This software turns your PC into a HPGL plotter. Very handy…
For creating the distortion and amplitude response plots, I use a couple of MATLAB scripts I have created:
Amplitude Response: HP8903A_Amplitude_vs_Frequency.m
THD+N versus Frequency: HP8903A_Distortion_vs_Frequency.m
These scripts are provided as-is without any warranty or responsibility of any kind.