Wimpy uses the new HTML5 WebAudio spectrum analyser to compute and render audio spectrums -- Note that some older (or crappy) browsers probably won't function properly, so use discretion when testing. However, Wimpy does include an automatic fallback "fake eq" if a browser is incapable of leveraging the new WebAudio features.
You can create your own renderer, or modify any of the existing renderers to suit your needs. Some types of music work better for certain renderers, also the size of the renderer also plays a role in how things look.
There are 2 example HTML files located in the "test" folder of the wimpy download package to show how you need to set up the HTML.
In a nut-shell, you'll first need to reference the renderer script (perfereably int eh <head> of your page), then for the wimpy player DIV, you'll set the renderer name into the "data-eq" option.