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2. The FFT Spectrum Analyser

1 The all-important FFT spectrum analyser dominates SPAN’s interface, showing the frequency response curve of the input signal chosen using the Group Channel Selector, with frequency on the X axis and amplitude on the Y. The info line at the top of the spectrum shows the frequency, note pitch and amplitude at the current mouse pointer position.

2 We’ll look at the Spectrum Mode Editor in the next video, but any presets made with it show up in the Mode menu. To get you started, a useful selection of Modes comes built in, each one defining the analysis Type, FFT Block Size, and vertical and horizontal Display Ranges, amongst other things. Run a signal into the plugin and step through the presets to get a feel for them.

3 The Hold button simply freezes the spectrum when activated, and releases it when clicked a second time. The menu next to it offers a palette of 16 colour options for the spectrum, and the Underlay menu lets you show the spectrum of any other channel group ‘behind’ the main spectrum for simultaneous analysis.

4 The FFT Spectrum Analyser display is fully zoomable using the horizontal and vertical scroll bars: drag their edges to zoom, then move them use the arrow buttons to navigate. Dragging the diamond button, bottom right, enables combined horizontal and vertical navigation, and double-clicking a scroll bar or the diamond toggles between its current state and fully zoomed out.

5 Holding the Alt/Option key and dragging within the display draws a box, which is zoomed into when the mouse button is released. Alt/Option-double-clicking zooms all the way back out. Clicking the spectrum resets it (important when using the Average analysis Type), and right-clicking it copies the frequency at that point to your OS clipboard, for pasting into an EQ plugin.

6 Ctrl/Cmd-clicking and holding the mouse button down applies a bandpass filter to the input, as clearly visualised in the display. Drag to adjust the frequency of the filter and its peak amplitude, and scroll the mouse wheel to narrow and widen its bandwidth. Using this, you can ‘solo’ specific frequencies in the signal in order to isolate problem areas.