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4. Spectrum Mode Editor
1 The Mode menu at the top right of the GUI hosts a selection of seven preset modes for the FFT Spectrum Analyser. These govern various parameters, including analysis Type and vertical and horizontal display Ranges. The parameters themselves are fully accessible in the Spectrum Mode Editor. Click the Edit button next to the Mode menu to pop it out in its own window.
2 Change preset, and the controls in the Spectrum Mode Editor jump to the new preset’s settings. The Spectrum Mode Editor has its own tool tips, turned on with the question mark button; and clicking the Presets button opens another window in which you can save, update and delete your own presets, which then appear in the Mode menu.
3 At the top of the Spectrum Mode Editor, the Spectrum Disable button kills the display entirely. Below that, the Filled Display button toggles the area below the spectrum curve between colour-filled and unfilled, and the 2nd Spectrum button activates a second, darker spectrum with its own Type setting, enabling two analysis styles within the one display.
4 Four analysis Types are independently available for the main and second spectra, selected in the Type and 2nd Type menus. RT Avg gives an averaged spectrum over a period of time dialled in via the Avg Time knob on the right. Intended for viewing the ‘perceived’ level of the signal over time, it’s a solid option whenever you need a general overview of what’s happening, such as on buses and the master output.
5 The RT Max Type shows the peak level curve, rather than the average, again falling away over a period of time set using the Avg Time knob. This is your best option when you want to see exactly where and by how much a highly dynamic sound source such as a drum kit is peaking across the frequency spectrum in precise, absolute terms.
6 The regular, non-RT Avg and Max Types generate cumulative spectra of their respective kinds with no fall-off over time; ie, building up to a solid spectrum that represents the peak or average curve over the entire monitoring period – infinite hold, effectively. They’re handy for getting an overview of the power distribution of a complete track, for example, or for highlighting persistent resonances.
7 The Block Size is loosely analogous to the analyser’s ‘resolution’. To simplify a complicated concept, higher Block Sizes give better frequency resolution (particularly evident in lower octaves) at the expense of timing precision. Generally speaking, the higher your sample rate, the higher you’ll need the Block Size to be.
8 The Overlap parameter represents the amount by which consecutive FFT blocks overlap in time, and can be thought of as the refresh rate. The higher its value, the faster the spectrum is updated, and the more CPU cycles are consumed. You’ll often need to use high Overlap settings when using large Block Sizes, and to get best results with the RT Max analysis Type.
9 The first four Display Range knobs set the frequency/amplitude boundaries for the spectrum display. The Slope knob ‘tilts’ the spectrum with the ‘fulcrum’ at 1kHz – with a setting of around 3dB-4.5dB/ octave, a mix that looks reasonably flat on the graph should sound well balanced to the human ear. The Smoothing menu sets the smoothing resolution in octaves for simplifying of the spectrum.