SPAN Plus is a real-time “fast Fourier transform” audio spectrum analyzer AAX, AudioUnit and VST plugin for professional sound and music production applications. For the most part it was derived from Voxengo GlissEQ dynamic parametric equalizer and reproduces its spectrum analysis functionality.
SPAN Plus is an extended version of the freeware SPAN plugin: SPAN Plus provides several additional features such as PNG file export, real-time spectrum import/export for cross-track spectrum comparisons, and static spectrums display.
SPAN Plus provides you with a very flexible “mode” system which you can use to setup your spectrum analyzer preferences. You may specify Fourier block size in samples, FFT window overlap percentage, spectrum's visual slope. Beside that you can choose to display secondary spectrum of a desired type (e.g. real-time maximum, all-time maximum). Spectrum can be smoothed out visually for an easier examination.
Beside cross-track spectrum comparison, SPAN Plus supports multi-channel analysis and can be set to display spectrums from two different channels or channel groups at the same time. Spectrum's color can be chosen to taste.
SPAN Plus also features output level metering with adjustable ballistics and integration time, EBU R128, K-system metering (including calibration K-system metering). SPAN Plus displays level metering statistics, headroom estimation and true peak clipping detection. Correlation metering is available as well.