The spectrum provides a real time display of the frequencies of the mix. This display helps with EQ'ing and adjusting the band cutoffs for multiband dynamics. Alloy can show two spectra, so users can see both peak and average spectra simultaneously in the display. By default, only a real-time averaging spectrum will be shown in the Equalizer and Mini-spectrum above the other modules.
Options
You can set options for the spectrum by accessing the Spectrum Options tab or right-clicking (under OS X you can also ctrl-click) the spectrum and selecting "Spectrum Options" from the context menu.