Excellent work John! Much obliged.
I have an important request. Please include an easy way to choose 25 dB/decade aspect ratio of the graph. Why? Read Don's Keele comments below:
"1. This aspect ratio is specified in an international standard IEC263 Dated 1982. Actually three are specified: 10, 25, and 50 dB/decade!
Here are images from the standard:
2. It prevents the manipulation of response data by changing the aspect ratio of a graph. Plotting response data on a compressed aspect ratio of 50 dB/decade or greater always makes the frequency response look better!
In interests of making comparisons of response data very easy, I always prefer to plot data on a 20 Hz to 20 kHz frequency scale with a 40 dB vertical range (usually 60 to 100 db SPL) and an aspect ratio of 25 dB/decade! I did this for all my Audio Magazine reviews!"
Example of a graph with 65 dB and second with 25 dB decade.