Support

Quick start

Open one audio file in A and another in B. SpectraNull decodes each source, aligns the pair, corrects polarity and applies one linked level match. Select Null in Monitor to see and hear the direct sample residual.

Null is joined by A, B, Common, Only in A and Only in B. Route any source as Stereo, Left, Mid, Mono, Right or Side.

Open files and folders

Each source pane always includes Open Audio File… and Open Folder…. Folder lists contain only loadable, nonempty mono and stereo files. Selecting a row loads it without closing the list.

Drop an audio file from Finder into A or B. Drag the document icon beside a loaded filename to move that file into another app. Drag the shared divider to resize the complete A, B and Monitor column. When a source file genuinely changes on disk, SpectraNull shows one red Reload button and waits for you.

Timeline and zoom

The bottom timeline is synchronised with every display. Click it to position the playhead, drag to select, drag either selection edge to adjust it, and press Escape to clear the selection. Time, frequency, level and selection read-outs sit below the ruler.

Scroll or pinch Spectra to zoom time and hold Shift for frequency. Spectrum uses ordinary scroll or pinch for frequency and Shift for level; signed Null level zoom remains symmetrical around 0 dB. Waveform and the timeline zoom time.

Space starts or stops playback at the cursor. With Loop enabled, playback starts at the beginning of the selected loop. Return stops and moves to the loop start, or to the file beginning when Loop is off.

Null playback

Boost raises the Null, Only in A and Only in B when the residual is faint. It starts at 0 dB and reaches 36 dB. An always-on −1 dBFS hard limiter protects the monitor output.

Normalise matched pair is enabled by default in the bottom bar. It applies one linked gain to A and B without changing their stereo balance.

Supported audio

SpectraNull accepts mono and stereo files. Analysis uses a canonical 48 kHz stereo pair. Mono is duplicated to Left and Right and therefore has a silent Side signal. Files with more than two channels are rejected.

Settings

Settings controls the Core Audio output device, alignment strategy, polarity correction, maximum alignment offset, manual fine offset and spectrogram display range. Normalise remains in the bottom-right transport area.

System requirements

macOS 14 Sonoma or later.

Privacy

Audio stays on your Mac. Read the privacy policy.