# Audio Multiband Stereo Width Three-band stereo imaging: mono the bass, keep the mids focused and widen the highs — exact mid/side matrices behind 4th-order Linkwitz-Riley crossovers, built from FFmpeg. > Canonical page: https://elysiatools.com/en/tools/audio-multiband-stereo-width - **Category:** Media - **Keywords:** stereo width, multiband imager, mid side, mono bass, stereo field, widen highs, linkwitz riley, crossover, mastering, stereo image ## Overview A mastering-style multiband imager. The stereo signal is split into low / mid / high bands by 4th-order Linkwitz-Riley crossovers (each boundary is two cascaded 2-pole sections — a single Butterworth pair was measured to sum with deep notches at the crossover frequency, while the cascaded LR4 sum is transparent to within 0.05 dB). Each band then runs through an exact mid/side matrix L′ = (1+G)/2·L + (1−G)/2·R, R′ = (1−G)/2·L + (1+G)/2·R, where G is the band's width control: 0% collapses the band to mono (the default for the low band — bass stays phase-safe for vinyl and club systems), 100% leaves it untouched, and up to 300% stretches it wide. Because the FFmpeg pan filter silently renormalizes channel coefficient sums, the matrix is applied with aeval expressions per channel, verified bit-exact at G = 1. The three bands are summed at unity (amix normalize=0) and a limiter guards the widened output. Before and after the render the tool measures the side-channel energy of the high band and the low band plus the mid-channel energy between the crossovers, so the report shows the width change where you asked for it and the collateral damage where you did not. ## Inputs - **Audio file** (file) - **Low/mid split (Hz)** (select) - **Mid/high split (Hz)** (select) - **Low band width (%)** (number) - **Mid band width (%)** (number) - **High band width (%)** (number) - **Output format** (select) ## When to use - Collapsing muddy sub-bass frequencies to mono to maintain phase coherence and club sound system compatibility. - Widening hi-hats, cymbals, reverbs, and top-end air without destabilizing centered vocal and snare tracks. - Polishing bus stems or complete master tracks with frequency-targeted stereo spread before distribution. ## How it works - Splits the input audio into low, mid, and high frequency bands using cascaded 4th-order Linkwitz-Riley (LR4) crossovers that sum flat without phase notches. - Applies exact mid/side transformation matrices to each band using configured width percentages from 0% (mono) to 300% (super-wide). - Sums the three bands at unity gain with a built-in safety limiter to guard against clipping, outputting the processed file in your chosen audio format. ## Use cases - Electronic and Dance Music Mastering: Tightening kicks and sub-bass below 120 Hz to mono while stretching synth pads and top-end percussion across the stereo spectrum. - Rock and Metal Production: Maintaining focused center-channel energy for kick, snare, and lead vocals while expanding drum overheads and stereo guitar layers. - Podcast and Broadcast Polish: Securing dialogue firmly in mono while letting stereo sound effects and room reverb gently breathe in higher bands. ## Frequently asked questions ### Why should bass frequencies be collapsed to mono? Summing bass to mono prevents low-end phase cancellation, improves punch, and ensures optimal playback on subwoofers, club PAs, and vinyl records. ### What crossover frequencies can I select? You can set the low/mid split to 120 Hz, 200 Hz, or 300 Hz, and the mid/high split to 4 kHz, 6 kHz, or 8 kHz. ### Does increasing high-frequency width cause phase cancellation? The tool uses exact mid/side matrix calculations verified bit-exact behind LR4 crossovers, keeping center-channel information intact while expanding side energy. ### What audio formats can I export? You can export your processed audio as MP3, WAV, FLAC, M4A, or OGG Vorbis files. ### What is the maximum supported file size? The tool accepts audio file uploads up to 100 MB per processing run. ## Related tools - [Album Art Extractor](https://elysiatools.com/en/tools/audio-album-art-extractor): Extract the album art from an audio file - [Audio Goniometer](https://elysiatools.com/en/tools/audio-goniometer): Render a polar stereo image to visualize width and panning - [Sub-Bass Mono Maker](https://elysiatools.com/en/tools/audio-sub-bass-mono-maker): Fold everything below your crossover to mono while keeping the stereo image above it — the elliptical-EQ move that protects vinyl cuts and mono-sub club systems. - [Image to Spectrogram Audio](https://elysiatools.com/en/tools/image-to-spectrogram-audio): Convert a bitmap image into reconstruction-first audio designed to reappear in a spectrogram, then export the audio and a verification spectrogram preview together. - [Audio Spectrogram Generator](https://elysiatools.com/en/tools/audio-spectrogram-generator): Generate a spectrogram image from an audio file or a video audio track - [Audio Waveform Generator](https://elysiatools.com/en/tools/audio-waveform-generator): Generate a waveform image from an audio file - [Convert ARW to JPEG](https://elysiatools.com/en/tools/arw-to-jpg): Convert Sony ARW RAW files to JPEG format. Automatically extracts image dimensions and metadata from the RAW file. - [Convert ARW to PNG](https://elysiatools.com/en/tools/arw-to-png): Convert Sony ARW RAW files to PNG format. Automatically extracts image dimensions and metadata from the RAW file. ## Samples - [Copyright-Free FLAC Audio Samples](https://elysiatools.com/en/samples/flac-samples): Lossless FLAC audio samples for testing and development, mirrored from MP3 set with nature sounds and meditation music - [Copyright-Free MP3 Audio Samples](https://elysiatools.com/en/samples/mp3-samples): Collection of royalty-free audio samples for testing and development purposes including nature sounds, meditation music, and ambient audio - [Copyright-Free WAV Audio Samples](https://elysiatools.com/en/samples/wav-samples): Uncompressed PCM WAV audio samples for testing and development, mirrored from MP3 set with nature sounds and meditation music - [Copyright-Free Raw PCM Audio Samples](https://elysiatools.com/en/samples/pcm-samples): Raw PCM s16le audio samples featuring nature ambience and relaxing music for waveform, playback, and conversion workflows